🔙 Quay lại trang tải sách pdf ebook Hóa Đại Cương – Vô Cơ – Tập 1 (Sách đào tạo Dược sỹ đại học) Ebooks Nhóm Zalo Tap 1 SACH DAO TAO DUQC ST DI HOC Cht) Nen: PGS.TSKH. Le Thanh Phii6c 411 BO Y Tg HOA DA1 CUING VO Ca TAP 1 CAU TAO CHAT VA NHIIET HONG HOA HOC SACH DA0 TAO [MC ST DAI HOC Ma s6: 0.20.X.05 Chu Wen: PGS.TSKH. LE THANH PHIIOC (Tcli ban lein thi'i nheet có seta chita vet be sung) TAN TAO UNIVERSITY LIBRARY NHA XUAT BAN Y HOC HA NOI — 2012 5-46 1-74Cle7f A 2_ o 1 (3464 CHI DA0 BIEN SOAN: Vu Khoa hoc & Dao tao, BQ Y td CHO BIEN: PGS.TSKH. La Thanh Phiteic NHONG NGUOI BIEN SOAN: 1. PGS.TSKH. Le Thanh Phu& 2. PGS.TS. Phan TOy 3. CN. Nguy6n Nhat Thi THAM GIA TO CHUC BAN THAO: 1. ThS. Phi Van Tharn 2. TS. Nguy6n Manh Pha © Ban quydn thuQc BQ Y td (Vu Khoa hoc va Dao tao) 2 LIN G Idl THIN Thus hien met so di6u cua Luat Gido due, Be Giao duc & Dao tao va WO' Y te' da ban hanh chuong trinh khung dao tao Ditoc si dai hoc. Bo Y to to chitc bien soan tai lieu day — hoc cac men hoc chuyen men, cd ban chuyen nganh theo chucing trinh tren nham titng buOc xay ding be tai lieu day — hoc chuan ve chuyen mon de dam bao chat Wong dao tao nhan luc y t6. Sach "Hod tai cu'dng — vo co' ditOc bien soan data vao clutOng trinh gido due dai hoc cita trItang Dai hoc Duoc Ha N'ei tren cd chttong trinh khung da ditoc phe duyet. Sach duoc bien soan theo pinking cham: kie'n thitc cd ban, he thong; not dung chinh xac, khoa hoc, cap nhat cac tie'n be khoa hoc, ky thuat hien dai va thiic tin Viet Nam. Sach "Hod dai curing — vo co"' da dude Men soan bai cac nha giao giau kinh nghiem va tam huye't dia be mon Hod dai cu'dng — vo cd, trUeng Dai hoc Duoc Ha Nei. Sach "Hod dai cu'ang — vo co"' da. doge Hei d6ng chuyen mon cita Bo Y te" tham dinh nam 2007. Be Y t6 ban hanh Cal lieu dat chuan chuyen men nay de sit dung cho nganh trong giai doan hien nay. Trong qua trinh sit dung, sach phai doge chinh 1ST, b'6' sung va cap nhat. Be Y te' xin than thanh cam on PGS. TSKH. Le Thanh Philac, cac chuyen gia cua tnthrig dai hoc Duoc Ha Nei da danh nhie'u tong site bien soan can sach. Cam on PGS. Ngo Si 'long va GS. Dam Trung Bac, da dot phan Men de cuo'n sach sOrn hoan thanh kip thai phut vu cho tong tac dap tao nhan lite y VI lan dau xuat ban, chi mg toi mong nhan dudc y kie'n dong gop cita do'ng nghiep, cac ban sinh vien va cac dec gia de lan xuat ban sau sach ditOc hoan thien hon. VU KHOA HOC VA DA° TAO BOYTE. 3 LC I Nol DAU Hod dai cifdng va vo cd la mon hoc trong chuong trinh ciao tao Duoc si dai hoc. Theo quy dinh cua chuong trinh khung, phan ly thuye't Hod dai cuong va vo co dttoc giang day nam this nhat cho sinh vien Dude he chinh quy. De dap Ting yeu eau chung ye nang cao chat Wong dao tao dai hoc va phuong phap giang day tich cuc, chUng toi bien soan giao trinh Hoa dai dicing - vo co theo hiidng tao dieu kien cho sinh vien to chi nhieu hcin trong hoc tap. Theo do, nhfing_kien fir& khoa hod hoc duoc sap xep, trinh bay mot each hop lY va he thong, vita co ban - hien dai, vita thiet thuc trong van dung, ke Ca lien he yell kien thlic Sinh - Y - Duoc hoc. Muc tieu cila mon hoc ma sinh vien can phai dat la: 1. Trinh bay va giai thich doge eau tao va tinti chat dia cac he vat chat (nguyen tit, nguyen to, phan tii, phlic chat, vat the) nha nhcing kien thfic co ban nhat ve Cci hoc Wong tit 2. Xac dinh va ly giai dtioc chi6u gidi han cua cac qua trinh hod hoc nha van dung cac nguyen ly cua Nhiet dOng hoc. 3. Giai thich dtioc cd the va cac dieu kien phan ling dua tren nhfing dinh luat cd ban clia hod hoc. 4. Chi ra dude each phan loai, giai thich dtiOc Ural chat, vai trO va dOc tinh dia cac nguyen to va hop chat vo co, dac bi't la nhang chat dticic quan tam trong Y - Duck. Tai li4'u nay chia lam 2 tap: - Tap 1 Om có 6 chuong, nham giup cho sinh vien thAic hien muc tieu 1 va muc tieu 2. - Tap 2 go'm có 5 chuong, nham giup cho sinh vien thuc hien muc tieu 3 va muc tieu 4. Cuo-i int3i quyen có kem theo cac phu luc de nguai doe tien tra Tau nhi6u hang s6, dai Wong hoac khai niem thuOng dung trong lioa hoc, ke ca danh phap chat vo cd theo Duoc dien Viet Nam. Trong qua trinh ,bien soan, cac tac gia rat co gang. Du vay, nhigu khie'm khuyet chat chap van con. Ch'ing toi rat mong nhan dude kien &mg gbp va phe binh cac dOng nghiep, sinh vien va ban doc de lan xuat ban sau tai lieu có chat Wong cao hon. Ha Noi, Thang 10 nam 2012 Chet bien PGS.TSKH. LE THANH PHU& 5 6 MUC LVC CHUONG 1. NHONG KHAI NIEM VA DINH LUAT CO BAN TRONG HOA HOC 11 PGS. TSKH. Le Thanh Phu'ac 1. D6i ttidng. Lddc sit hoa hoc 11 2. Khai niem cd ban ve dac tinh va phan loci cac chat 13 2.1. Tinh chgt cita vat chgt 13 2.2. Ba trang thai cita vat chgt 14 2.3. Nang Wong trong nghien citu vat chgt 15 2.4. Nguyen to, hop chgt va han hop. Tang quan ve nguyen tit 16 3. Cac dinh luat cd ban ciia hoa hoc. Thuygt nguyen tit dm Dalton 19 3.1. Dinh luat bao toan khai Wong cua Lavoisier va Ldmonoxov 19 3.2. Dinh luat thanh phan khong dai ciia Proust 20 3.3. Dinh luat qr le bQi cita John Dalton 21 3.4. Thuye't nguyen tit cita Dalton 22 3.5. Tranh luan v6 khai Wong nguyen tit. Dinh luat Gay-Lussac va. Avogadro. 23 4. M'Ot s6 ddn vi cim he SI quan trong trong hoa hoc 25 5. S6 hieu nguyen tit, s6 kh6i, IKST hieu hoa hoc 29 6. piing vi va khgi lu'dng nguyen tit cua cac nguyen to 30 6.1. Dang vi 30 6.2. Khai Wong nguyen tit 31 6.3. Khai Wong nguyen tit clang vi va•khai Wong nguyen tit cita nguyen to 31 7. Mol 32 8. Cac dinh luat vg trong thai IchilS7tiiiiing. The tich mol cua cac chat khi 36 9. thicing lu'dng 39 CHUONG 2. CAU TAO NGUYEN TO% He THONG TUAN HOAN CAC NGUYEN TO HOA HOC 42 PGS. TSKH. Le Thanh Phu'dc, CN. Nguyjn Nheit Thi 1. Cu tao nguyen tit 42 1.1. Thanh phan chinh cit' a nguyen tit 42 7 1.2. Mau nguyen tit trttoc cd hoc trong tii 43 1.3. Mau nguyen tit theo co hoc luting tit 51 2. He thong tuan hoan cac nguyen to hod hoc 90 2.1. Dinh lust tuan hoan va he thong tuan 'loan cac nguyen to hod hoc 90 2.2. MO't so tinh chSt tuan hodn cua cac nguyen to 100 CHUONG 3. LIEN KET HOA HOC VA CAU TAO PHAN TO' 109 PGS. TS. Phan Tu 1. Lien ket hod hoc khong dita tren cd hoc Itidng 109 1.1. Nhiing thuyet v6 lien ket hod hoc 109 1.2. MOt so tinh chSt cua phan tit 113 2. Lien kgt hod hoc theo co? ltidng t 118 2.1. PIntong phap cap electron h6a tri - phuong phap VB 119 2.2. Pintong phdp orbital phan tit - pinking phdp MO 142 2.3. Orbital phan tit dinh xit, phan dinh xtt va pinking phdp MO — Huckel 153 CHUONG 4. PHUC CHAT 159 PGS. TS. Phan Tu3; 1. Dinh nghia va cac thanh phAn cua phitc chk 159 2. Phan loai phitc chk 161 3. Dong phan cua phiic 162 4. Danh phap phitc chk 163 5. Su then ly va Wang se; khong b6'n cua phitc chk 164 6. Lien kgt hos hoc trong phitc chk 165 6.1. Thuyet lien ket hod tri (thuyet VB) 165 6.2. Thuyet tritOng tinh the 167 6.3. Thuyet MO va lien ket trong phitc chSt 175 CHUONG 5. CAU TAO VAT THE - PHAN cvc ION 180 PGS. TSKH. Le Thanh Phu'dc 1. Lien kgt giita cac phan tit 180 1.1. Lien ket Van der Waals 180 1.2. Lien ket hydro 185 2. Cac trang thai tap hdp chk 190 2.1. Trang thai khi 191 2.2. Trsng thdi long 192 8 2.3. Chat ran 193 3. Phan cifc ion 207 3.1. Dai cuong 207 3.2. Anh twang cua phan cuc ion den tinh chat cac hop chat 209 CHLiCING 6. NHIET HONG HOA HOC 225 PGS. TSKH. Le Theinh Phu'dc 1. Nhiet hoa hoc 225 1.1. Nei nang 226 1.2. Enthalpy 231 1.3. Hieu iing nhiet cna cac qua trinh hod hoc 235 1.4. Si phu thuec cua hieu fing nhiet vao nhiet de. Dinh luat Kirchoff 239 1.5. Phuong phap xac Binh hieu iing nhiet cua phan Ting. Dinh luat Hess 245 1.6. Sinh nhiet AH (f) 251 1.7. Nhiet chay AH (comb 253 1.8. Nhiet bie'n del trang thai 255 1.9. Nang luong lien ke't tong hoa tri 257 1.10. Nhiet hydrat hoa cUa ion 263 2. Van dung Nguyen IS7 II cua Nhiet dOng hoc de xet chie'u hating va gi ii han cua cac qua trinh hofi hoc 264 2.1. Entropy (S) 265 2.2. Entropy, Nang Wong tai do Gibbs va C6ng 283 3. The hoa hocµ 295 PHI) LVC 299 PGS. TSKH. Le Themh Phu'dc (Phu luc 3, 4, 7) CN. Nguyen Nheit Thi (Phu luc 1, 2, 5, 6) Phu luc 1. Wit s6 thong tin v6 cac nguyen to hoa hoc 299 Phu luc 2. Ham Wong tuong dei cua cac nguyen t6 trong va qua dat 306 Phu luc 3. Cac gia tri AH °f, AG (f), dia cac chat va ion 307 Phu luc 4. Danh phap chat vo co theo aloe din Viet Nam 317 Phu luc 5. He thong don vi queic t6 SI 325 Phu luc 6. Cac hang so-vat 1ST 329 Phu luc 7. Si khong chat than trong do Wang. Chu s6ce nghia trong hoa hoc. Su chinh xac, do chinh xac va sai s6 330 9 10 Chtictrig 1 NHIING KHAI NIEM VA DINH LUAT CO BAN TRONG HOA HOC MUC TIEU 1. Trinh bay dude not dung vet y nghia clict cac dinh 1u4t cd bcin ctat nen mOng cho hoa hoc hien dai. 2. Phan tich du'qc chinh xac cac khai niem: nguyen nguyen t6, thing vi, pha n mol, &icing lito'ng. 1. Do! TONG - LIfOC SU' HOA HOC Hod hoc la khoa hoc nghien citu cau tao va tinh chat ciia vat chat, cac qud trinh bien d6i ma cac chat phai trai qua clang vai nang Wong di kern nhang qua trinh do. Hod hoc c6 mat lich sii phong phu, nhieu mau sac. Nhiing net chinh vg cac dot pha ban dau, ke ca nhang sai lam duoc gioi thieu dtioi day se cung cap cho chting to cai nhin vg sti khai ngan ciia hod hoc hien dai va khoa hoc nay da phat trien ra sao. * Thai kY tign hoa hoc: go'm 3 thai ky ch6ng Fan nhau la gia kim thuat, y hoc va cong nghe. — Thai ky gia kim thuat: Nhiing nghien citu huyen bi vg tii nhien cua nhcing ngtfai Hy Lap a Bac Ai Cap the kY thli I sau COng nguyen ma mai sau nay van con not tieng vdi cal ten gia kim thuat (alchemy). Nhiing nghien dm do loang r6ng tit Can Deng tai chau Au, sau do con anh twang den suy nghi cua phucing Tay cho den tan the V XVI. Y Wang cua nhiring nguai Hy Lap cho rang vat chat bi'en d6i mot each tti nhien de tra nen hoan hao; c6 the tim each Eden cac chat it gia tri, vi du nhu chi, thanh nhi-ing chat quY gia, vi du nhtf yang. Tit do, ho clang tin rang c6 the dieu the dude thu6c truang sinh, by vong keo dal mai tu6i thanh xuan. Nhang suy nghi khong c6 can cif tat nhien khong dtia den ket qua nao. Nhiing gi khoa hoa hoc thila ke cua gia kim thuat chi la sti khuyen khich quan sat va thuc 11 nghiem, thay cho nhiing nha trigt hoc tilt& do nghien citu ttt nhien chi bang con dila/1g duy 1Y. - Thai kY y hoc: Cdc nha gia kim thuat c6 anh hang 16n den y hoc o chau Au thai Trung Co. Tit thekSTXIII ngttai ta- da. cluing cat re, cay co va cac thuc vat khdc de lam ngudn thu6c. Paracelus (1493 - 1541) la met nha hod hoc tiCh cue va nha vat,lY quan trong trong thai gian nay. Nhang tai lieu cila Ong lai hibu, nhttng &tang flint ong tin rang co the con nguai la met he hod hoc ma sti can bang cac chat trong no c6 the phuc 116i nho dieu tri bang y hoc. Nhitng hoc tro cua Ong da che ra met s6 thu6c khodng chat cho cac hieu thu6c vao thekSr XVII. Mac du met s6 trong cac thu6c nay khong c6 ich va met s6 c6 hai, nhung sau do cac nha thUc hanh da dp dung cac thu6c khodng chat khdc va da thanh cong. Tit do bat dau met moi quan he y hoc va hod hoc phat trien manh me cho tdi ngay nay. - Thai kY cong nghe: Trong hang ngan nam, con ngu6i da phat trien nhieu ky xao cong nghe de thttc hien nhitng bign d6i vat chat. Lam de g6m, thu6c nhuem va dac biet la luyen kim (bat dau cach day khoang 7000 nam) da gop phan to lon vao sti hieu biet cua chang to ve tinh chat cila vat chat. Trong thoi ky Trung Co va Phuc Hung, ky nghe phdt trien hang thinh, c6 met s6 cong trinh nghien citu da ghi lai ye luydn kim. Cdc tai lieu nay mo to each tinh che, dinh htong; each chic bac va yang; cach sit dung can, 16 nung, not nau kim loci; cach che tao thug tinh, de g6m, thu6c nhuem, thu6c Nhieu sang tao cua tho thu tong thai kY nay van con lai den ngay nay. Met s6 tai lieu con cho thay da c6 quan tam tim hieu tai sao met chat hien d6i va lam cach nao de tien doan st,t bien d6i ciia vat chat. Tuy nhien, trong thai kY nay c6 met 15r thuyet sai lam (dau an tit thai alchemy), do la thuyet phlogiston. Mac du Eta da duoc sit dung tit till:3i tien nhung khong c6 met giai thich nao hop lY ve nguyen nhan tai sao mot s6 chat lai chay ma nhiing chat khdc thi khong, hoac dieu gi se xay ra khi met chat chay. Thuyet phlogiston cho rang, cac chat chdy duoc la do chita phlogiston (met chat nhe khong the phdt hien duoc) va phlogiston se giai phong ra khi chat chdy. Chat a chdy chita nhieu phlogiston, chat chdy it hoac khong chdy thi chita It hoac khong có phlogiston. Rei de giai thich nhiing mau thu'an NT& thitc nghiem, thuyet nay con cho rang phlogiston c6 khol Wong am! Thuyet phlogiston sai lam, nhung no da thong tri suy nghi vd stt chdy trong gan 100 nam. Cho den khi nha hod hoc tre nguoi Phdp Antoine Lavoisier (1743 - 1794) chitng minh rang, ban chat cila su chdy la qud trinh ket hop dm cac chat voi oxy, met thanh phan cua khOng khi. Thuyet cua Lavoisier ye stt chdy thanh cong vi no giai thich duoc moi dieu quan sat met cach ra rang va vfing chat. Quan trong la thuyet moi nay Oa tren nhang do Kiang dinh Wong chit khong phai dila tren cac tinh chat kY la cila nhiing chat khong the phat hien &loc. Vi 12 htfdng tigp can nay la trung tam cua khoa hoc nen nhigu ngvai cho fang, khoa hoc hod hoc da bat dau voi Lavoisier va Lomonoxov (Mikhain Vaxilevich Lomanoxov, nha hod hoc ngtthi Nga, 1711 - 1765), vi hai Ong da dOc lap thigt lap dvoc dinh lust bao toan khoi lvong (ma chUng ta se dg cap tOi d phhn sau). * Tit Lavoisier va Lomanoxoy, có thg coi thai ky tin hod hoc da chim &it va hoa hoc hikn dai bat dau voi hang boat cac dinh lust co ban dVoc phat minh: dinh lust bao toan khoi Wong, dinh lust thanh phan khong d6i, dinh lust doing Wong, dinh lust Avogadro, dinh lust tun hohn cac nguyen to cUa Mendeleev, cac nguyen ly cua Nhigt dOng hoc. Nhang dinh lust nay lai dat nen mong cho sit ra dai hoc thuygt vg nguyen tit, phan tit ma nhting nguai có ding dau xay thing la cac nha hod hoc n6i tigng: Dalton, Gay Lussac, Robert Boyle, Berzelius, Avogadro, Canizaro... * Sang ddu the V XX, cac nha vat 1ST di tier' phong da kham pha ciu tao ben trong nguyen tii, dva ra cac.mo hinh nguyen tii, va sau do da xay dung ca mot 1ST thuygt hung manh dg con ngvai tign ding vao the gioi vi mo, do la Co hoc hiOng tit. Co hoc Wong tit ra dai nha cong lao cU.a ca mot lop cac nha bac hoc xuit sac: Max Planck, Niels Bohr, Werner Heisenberg, Erwin Schrodinger, Louis de Broglie, Albert Einstein, Paul Dirac, Max Born, Enrico Fermi, Wolfgang Pauli... Nha CO hoc Wong tit, ngay nay thong ta hieu bigt sau sac va bign chiing 6 ca dinh tinh va dinh luting cac quy lust hoac vin de: ddm may phai thay cho quy dao electron; trang thai cila electron trong nguyen tii phai dvoc dac tiling bang 4 s6 luting quy lust vg sv tun hoan cac nguyen t6; ban chit cac loai lien kgt hod hoc; ciu trot phan tit cUa chit song; quang ph6; laser; vat l.S7 chit ran; din tra va sieu dan; vi mach din tit; ciu tao hat nhan nguyen hikn Wong phan ra ph6ng xa; sit hinh thanh, ciu tao va Wong tdc cua cac hat co ban. 2. KHAI NIEM CO BAN VE DAC TiNH VA PHAN LOAI CAC CHAT Hod hoc gan lien voi mot &di tvong kh6ng to - do la toan b6 vat chit cUa vu tru. De suy nghi dvoc minh bach, can bat dau v8i cac khai nikm va dinh ngliia co ban, cho du có nhung dinh nghia da quen thuoc vdi mot so-nguai. 2.1. Tinh chgt cua vat chgt Vat chit la chit ligu cua vu tru. Bat tit vat nao cling có the tich va khoi lu'cing. Hai dai Wong nay &toe dinh nghia data tren cach do Wang chUng: thg tich (V) là phan khong gian ma vat chigm giii, khoi Wong (m) la Wong vat chit chita trong luck vat. Digu quan tam dac bit cua nha hod hoc la thanh phan cila vat chit: loai nao va s6 Wong bao nhieu cac chit don gian da ciu tao nen mot mhu vat. Chung ta nghien dm vat chit bang cach quan sat cac tinh chat cila no. M6'i chit, m6i vat có mot so tinh chat dac tru'ng khign cho no co mot dac ctiem nhein clang duy nit& Co 2 loai tinh chit: tinh chit vat lST va tinh chit hod hoc, dO la 2 loai bign doi có lien quan chat the ma vat chit phai trai qua. 13 Tinh chat vat ly la nhang tinh chat ma *it chat thd hidn khi kh6ng co Wong tac yell chat khac. VI du: mau sac, didm nong chay, didm soi, d6 dan didn, tST trong. M6t bien cai vat ly xay ra khi mot chat thay doi trang thai hay hinh dang nhung khong thay &Si thanh phan. VI du, khi nude da nong chay thi c6 mot s6 tinh chat vat ly thay doi nhti d6 ding, tY' trong, tinh linh d6ng... nhung no van la ntioc. Tinh chdt hod hoc la nhilng tinh chat cUa mot chat the hidn khi hiring tac voi chat khac, hoac khi tit bidn d6i thanh chat khac. Vi du, tinh de chay, tinh bi an mon, kha nang phan itng voi acid. M6t Nen doi hod hoc, con goi la phdn zing hod hoc, xay ra khi mot chat (hoac nhidu chat) chuyen thanh mot chat (hoAc nhidu chat) khac c6 thanh phan va tinh chat khac voi chat ban dau. Vi du, khi thing dien chay qua nueic gay ra mot phan itng hoa hoc, nitric bi phan huY thanh 2 chat la khi hydro va khi oxy. Hai kill nay c6 tit-1h chat vat 1ST va tinh chat hoa hoc khac nhau va khac voi nuoc ban dau. MOt chdt du'o'c xac dinh b& mot tap kip cdc tinh chat vat ly vet hod hoc . d4c tru'ng. Vi du, mot s6 U./1h chat cUa d6ng d Bang 1-1 cho thay: chat voi tap hop cac tinh chat nhii vay chi c6 thd la d6ng. Bang 1.1. M6t s6 tinh chat dec tru'ng cCia thing kim loai Tinh chat vat ljr Tinh chat hoa hoc Mau do n5u, anh kim. Chuygn dan thanh hop chat carbonat De dat mOng, keo dai. Dan nhiet va dan dien tot. Khi nong ch5y có thg h6n hop veil kern mau xanh trong khong khi gm. Ph5n (trig voi acid HNO3, H2SO4. Chuygn den thanh mau xanh dem tao ra d6ng thau. trong nu'dc amoniac. Kh6i lacing rieng = 8,95 g/cm3. Digm nong ch5y = 1083°C. Digm s6i = 2570°C. 2.2. Ba trang thai cua vat chgt Vat chat ton tai d 3 clang, hay 3 trang thai vat 1S7: ran, long, khi. M6i 7 trang thai diioc xac dinh bai each vat chat lam day binh chiia. Chat ran c6 hinh clang co dinh, khong nhat thidt phai phu hop voi thanh binh. Liiu ST: chat ran khong dinh nghia bdi d6 ran chAc hay d6 sat rat ran chat, chi ran linh d6ng hon, con sap ong ran nhung mem deo. Chat 16ng plia hop voi hinh Bang cUa binh chita bang the tich cUa no, vi vay chat lOng tao thanh mot be mat. Chat khi clang phu hop voi binh Chita, nhung no lam day toan 136 the tich cua binh, vi vay chat kill khong tao thanh be mat. 14 Nhidu chat c6 thJ ton tai ci ca 3 trang thai vat 1ST va c6 thd bidn d6i qua cox trang thai tuST thuec nhiet de va ap suat moi tritang. Khi nhiet do tang, nudc c/a nOng chay thanh nudc lOng va khi nitric soi thi tao thAnh nit& khi (hdi nuoc). Qua trinh ngttoc lai xay ra khi ha nhiet do: hdi midc ngung to thAnh nitric lOng va se &lig bang. Nhie'u chdt khdc cung bie'n d6i Wong tit: sat ran nOng chay thanh sat lOng va d nhiet ctO soi bidn thAnh hdi sat. Lam lanh hdi sat lai thu ditoc sat lOng roi den sat ran. Lvu ST la bien ctoi vat ly có the' chuye'n dei hai chie'u theo nhi0 dO, nhu'ng bier' cal hod hoc thi khong. D6t 'long thitang gay ra met bidn d6i ,hod hoc ma lam lanh khong thd ciao nguoc ditoc. Chang han, ndu dot nong sat trong khong khi am tin, met phan iing hod hoc xay ra, tao thanh mot chat mail nau, vun la. gi sat (sat oxyd). Qua trinh lam lanh gi sat khong thd tao 14i sat ran ban dAu. CAn co met hoac met chu6i phan ang khac mdi thus hien &toe qua trinh nay. Hoac taring -b.!, d nhiet de cao da vdi (calci phan huST' thAnh voi (calci oxyd) va. khi carbonic; nhung khong the tren voi voi khi carbonic de tao ra toan be da voi ban dau chi bang • the cach lam lanh him hop do. 2.3. Nang hiring trong nghien ciiu vat chgt Moi bidn &I vat 1ST va hod hoc deu di kem sit bidn d6i nang Wong. Nang lu'dng du'Oc dinh nghia la khd nang sinh tong, là thu'oc do mac d'O vdn d'Ong cua vat chdt. Nang Wong town phan dm met vat bang tang deng nang va thd nang cua no. The nang là nang Wong có &toe do vi tri cua vet. D'Ong nang là nang Wong c6 &toe do chuyen dcmg cua vat. Vdt d thd nang cao hdn là trang thai it on dinh hdn, the nang thap hon là trang thai on dinh hdn. De khai niem gAn voi hoa hoc, ta lay vi du 2 qua bong ditoc gan vdi nhau bai met 16 xo. Khi ta keo qua bong 1/6 mot phia, nang Wong keo cua tay ta lam cang 16 xo, titc IA lam tang thd nang cUa no. Luc nay 16 xo kem on dinh lion (do nang hiring cao hdn) so vdi trang thai gian tit do. Neu ta tha tay ra, cac qua b6ng chuy6n crcing lai gdn nhau, the nang da chuyen thanh &Ong nang. Ta cung c6 the lam tang thg nang bang cdch nen 2 qua bong lai, tiic là ep 16 xo lai. Khi tha tay, 2 qua bong se chuyen dting xa nhau ra, sii thay doi the nang lai chuyen thanh deng nang. Di nhien khorig có cai 16 xo trong met chat nal) do, nhung met he hod hoc cung airing tit nhu v437 v6 m'a't nang Wong. Khi that hien tach tidu phan tich dien am ra kh6i ti6u phan tich dien diking (giong nhtt khi keo cang 16 xo) thi the nang cua cac ti6u,phan tang. Thd nang (Moe giai phong se chuyen thanh deng nang khi cac tieu phan chuyen deng 1.4i gdn nhau. Khi hai tidu phan cling dau dien tich bi day lai gar' nhau (giong nhtt khi nen 16 xo) thi thg nang cung tang, va khi dJ chUng ditoc chuydn deng xa nhau ra thi thd /fang &toe giai phong va chuydn,thanh deng nang. Hai tidu phan khac dau dien tich gAn nhau, hoac hai tieu phan cling &Au dien tich d xa nhau la hic he cuc tidu ve thd nang (trang thai nang Wong tha.p h6n) nen b6n hon. 15 M6t s6 chat giau /tang lityng hod hoc hdn cac chat khdc là do vi tri Wang doi va sit Wong tdc Oita cac tieu phan cita chting. Nhung chat nhti the dttOc sit dung lam nhien lieu hay thitc an, chting chia nhieu the nang hdn cac chat thai dtroc tao thanh. Khi et& chdy xang trong Ong co otO, cdc chat co the nang hod hoc cao hdn (xang va oxy khong khi) dttoc chuyen thanh cac chat c6 the nang hod hoc thgp hdn (khi thai, trong do co CO2va H20). Stt khdc nhau ve the nang nay (bang the nang &toe giai pilot-1g) chuyen thanh Ong 'tang lam xe chay, lam nong khong khi xung quanh, lam den bat sang v.v... Clang Wong 41, sit khdc nhau ve the nang gifia thitc an va oxy khong khi chting ta tha vao so voi cac chat thai bai tiet ra dttoc sit dung de co the van dOng, sinh trading, gift gm, tut duy v.v... Can nho la nang Wong luon duoc bao toan: no khong tit sinh ra hoac mat di ma chi chuyen tit dang nay sang dang,khd.c. mot he kern ben chuydn thanh h'ebJn hdn khi mot phdn thd nang chuyen thanh dOng ming, nang luting nay de thu'c hien tong. 2.4. Nguyen to, help chgt ya. hen hcip. Tang quan ve nguyen tit Vat chat co the phan chia rOng rai thanh 3 loai chat, trong do c6 2 loai: nguyen to va hop chat dttoc xem la nhfing chat tinh khidt vi co thanh phan on dinh, loai this ba goi la hen hop vi co thanh phan khong co dinh. Nguyen to (element) la loai chat don gian nhat co ,cac tinh chat hod hoc va. vat 1ST duy nhat. M6‘i nguyen to chi g6m mot loai nguyen tit, no khong bi phd va thanh nhang chat don gian hdn bai cac phitong tien vat lST hay hod hoc thong thttang. Al& nguyen to co mot ten va mot l(ST hieu rieng, nhu carbon (C), oxy (0), d6ng (Cu) v.v... MOt mau carbon chi g6m cac nguyen tit carbon, co cac tinh chat rieng ve mau sac, ty trong, tinh de khac voi mot mau d6ng, bcii vi tinh chat cila cac nguyen tit carbon khdc voi tinh chat caa cac nguyen tit d6ng. Do d6 mei nguyen t6 co tinh duy nhgt. Hau het cac nguyen to ton tai trong ttt nhien duoi dang tap hop lon cua cac don nguyen tit (Hinh 1.1A), nhung cang co mot se nguyen to ton tai dttoi dang phan tii: mei phan tit la mot c'g.0 true g6m hai hay nhieu nguyen tii lien ket hod. hoc voi nhau tao thanh mot ddn vi dOc lap (chang han khi oxy, nitd trong khong khi dttdi dang 2 nguyen tit; Hinh 1.1B). Nguai ta cling goi chat do nhang nguyen tit ding loai eau tao nen la ddn chdt (thuc chat la nguyen to). Hop chat (compound) la nhang chat duoc tao thanh bai hai hay nhieu nguyen to ket hop veil nhau. Cdc nguyen to trong hop chat khong phai ditoc trOn lan voi nhau, ma •la dttoc lien ket hod hoc voi nhau de tao thanh mot hop chat moi (Hinh 1.1C). Amoniac, nttoc, carbon dioxyd la nhang hop chat phO hien. MOt dac diem ro rang cila hop chat la cac nguyen to co mat trong hop chat nhung ALA c6 dinh theo khOi Wong (tST le khoi Wong co dinh). Co dttoc tY)le nay vi hop chat Om mot 67' le c6 dinh s6 nguyen tit cita cac nguyen to tao thanh no. Vi du, khOi. Wong cila bat eft mau amoniac nao cang deu Om 14 phan khOi luong nito va 3 phan khOi Wong hydro. MOt nguyen tii nito co kit& tong gap 14 lAn khOi Wong 1 nguyen tit hydro, vi vay 1 phan tit amoniac g6m 1 nguyen tii nitd va 3 nguyen tii hydro. 16 MOt dac diem rO rang nila cua hop chat la tinh chat cua no khac vdi tinh chat cua cac nguyen to' thanh phdn. Vi du, kim loci natri mau trang bac, phan ling manh liet vdi nude, va khi clor dOc, mau yang xanh c6 tinh chat rat khac viii hop chat ma cluing tao thanh la tinh the mai an (natri clorid) mau trang, vi man, khOng dOc. Hop chat co the bi pha vd thanh cac nguyen to thanh phAn khi xay ra nhfing bie'n doi hod hoc, chang han khi phan huSr muoi an (NaC1) bang dOng dien se tao thanh natri kim loci va khi clor. Bang 1.2 cho thay sit khac nhau v6 tinh chat giiia hop chat va cac nguyen to thanh phdn. Bang 1.2. M0t so tinh chat cua natri, clor va natri clorid Tinh chgt Natri + Clor —> Natri clorid Digm nang chAy Diem s6i Mau Kh6i lu'ong rieng Vol nil& 97,8°C 881,4°C anh bac 0,97 g/cm3 phAn Ung manh Het -101°C -34°C yang xanh 0,0032 g/cm3 it hob tan 801°C 1413°C khong mau (tr5ng) 2,16 g/cm3 hoa tan nhi6u Hjn hop (mixture) la mot tap hop g6m hai hay nhieu nguyen to vaiho4c hop chat ditoc trOn ldn vdi nhau \re mat vat 15r (Hinh 1.1D). Ngtioc vdi hop chat, thanh plidn cua hOn hop c6 the thay doi rat rOng theo phdri khoi luong. VI hO'n hOp la su trOn lan vat 1Sr cac chat, chic khong phai bang cac lien ke't hod hoc, nen hon hop van mang cac tinh chat ciia cac thanh phdn ciia no. Nhu nu6c muoi chang han, khong matt nhil ntidc va c6 vi man nhu muoi. Kha.c vdi hop ch't, hon hop c6 the bi chia tach thanh co.c. thanh phan dm. no nha nhiing bie'n doi)vat 15r, chit khong can nha den bie'n doi hod hoc. VI du, nit& muoi c6 the tach ra cac thanh plidn nha qua trinh bay hdi milk, de lai muol natri ran ke't tinh. • ■ / • 0 A B C D Cac nguyen Cac phan tit Cac phan tCr H6n hop cua cua mot nguyen to cua mot nguyen to cua mot hop chat hai nguyen to va mot hop chat Hinh 1.1. Cac nguyen to, hop chat va h6n hop theo cap d6 nguyen to A. M6t nguyen to gom cac nguyen tit gi6ng nhau, nhu'ng chi c6 mot s6 nguyen to ton tai du'di dang nhCing nguyen tit rieng biet. B. M6t s6 nguyen to khac ton tai 6 dang cac phan tit. C. M6t phan cua mot hop chat bao g6m mot s6 nhat dinh cac nguyen tit cua hai hay nhieu nguyen to. D. M6t h6n hop chira nhang thanh ph5n rieng biet cua hai hay nhieu nguyen to va/hoac cac hop chat du'oc trOn an mot each vat ly veil nhau. TAN TAO UNIVERSITY LIBRARY 17 Hinh 1.2 la tong quan ye each phan loai vat chat theo quan diem hod hoc. Nhiing clang ddc biet khac cila vat chat hodc nhfiing trang thai trung gian cua cac chat chua de cap 6 day. - Cac phudng phap vat IY tach 11"6n hop thanh cac nguyen to'va cac hop chat. . - Phan tang hod hoc bie'n de;i cac nguyen to thanh cac hop chat, va ngudc lai; hoac cac hdp chat thanh nhiing hdp chat khdc. VAT CHAT CO khoi lacing va th6 tich T6n tai o 3 trang thai: ran, lOng, khi HON HOP - Hai hoac nhi6u nguyen to hoac hop chat theo tj, le kh6ng co dinh A thanh phan - Cac thanh ph5n van giit tinh chat hang cila chi:mg H6n hop kh6ng &ng nhit - Nhan ra du'oc cac thanh phan - Cac phan cUa he la khac nhau Hon hop d6ng nhit (dung dich) - Kh6ng nhan ra cac thanh phan - Cac phan cita he giong nhau Cac nguyen to CAC PHUONG PHAP TACH VAT Li' Loc Chigt Ly tam Cat Kat tinhtthang hoa Sac ky... CAC CHAT TINH KHIET Thanh phan xac dinh va dang nhat Hop chit - G6m mot loai nguyen tit - Chia thanh: kim loai, phi kim, a kim - Dang don gian nhat cUa vat chat con gist du'oc cac d5c tinh rieng - Kh6i lacing nguyen to la s6 trung binh cita cac kh6i lacing d6ng vi ph6 bian - Hai hoac nhi6u nguyen to lien kat theo ph5n kh6i lacing xac dinh - Tinh chit khac voi tinh chat cUa cac nguyen to thanh ph5n - Kh6i lacing phan tit bang tong kh6i lacing cac nguyen tit Cac nguyen til CAC PHAN ONG HOA HQC Cac hop chit ion - Proton (p') va notron (n°) tao thanh hat nhan dien tich during va qt.,* dinh kh6i luting nguyen tit (rat nhO) - SO = so hiau nguyen tit (Z) - Cac electron chiam th6 tich quanh hat nhan. SO p' = so - Tinh the' g6m cac ion Wong va ion am - Cac ion hinh thanh doe chuyan tit kim loai sang phi kim Cac hdp chit c6ng hoa tri - ThuOng gOm cac phan tit rieng biat - Cac nguyen tis(thuting la phi kim) lien kat yeti nhau be i cap electron hoa bl clOng chung Hinh 1.2. Ph5n loci vat chat theo hoe hoc 18 3. CAC DINH LUAs..T CO BAN CUA HOA HOC - THUYET NGUYEN It CUA DALTON Cdc dinh luat cd ban slat nen m6ng cho hoc thuyet nguyen tit - phan tit hien dai ma Dalton (John Dalton, nha hod hoc va vat 1ST ngtfai Anh, 1766 - 1844) la ngttai dau tien de xuat. Nha cdc dinh luat cd ban va hoc thuyet nguyen tit - phan tit eh-Ling ta mai c6 nhcing cd sa de tinh town dinh Wong trong khoa hod. hoc. 3.1. Dinh 1u4t bao toan khol 'tic/11g caa Lavoisier va Ldmanoxov Khoi lu'o'ng tong tong dta ccic chdt khOng cat trong mot phcin zing hod hoc. S6 Wong cdc chat va tinh chat cilia chUng c6 the thay doi, nhung khei Wong cua cdc chat thi gilt nguyen khong dol tritac va sau phan itng. Ngay ca nhang hien d6i sinh hoc phlic tap trong co the c6 lien quan den nhieu phan itng thi khol Wong van cluoc bao than: 180g glucose + 192g khi oxy -> 264g carbon dioxyd + 108g nitac (372g nguyen lieu truac phan itng --> 372g chat sau hien del) Nam 1905, A. Einstein (Nha vat 157 Dlic, 1879 - 1955) dita ra he thfic v6 mei quan he glib. kh6i Wong (m) cua vat va nang Wong (E) cua no: E = mc2 (1-1) day: c la t6c de dnh sang trong than khong bang 2,997925.108m/s (gan bang 300.000 km/s). Nhu vay, dinh luat bao toan kh6i Wong chi hohn toan dung cho phan ang khong thu hoac phat ra nang Wong. Trong truang hop nglicic lai, kh6i luting cac chat c6 the tang (khi hap thu Wong nhiet Q) hoac giam (khi toa ra Wong nhiet Q) Wong fing vai hien thien khol Wong (Am): Q (=AE) Am = (1-2) C2 Tuy nhien, vi c2 la rat kin, Nen d6i khel luting caa chat theo nang hiOng trong cdc phan Ung hod hoc la rat nha, nen that to khoi lu'o'ng van du'vc bdo town. [Ngttoi ta tinh rang, khi 100g carbon chdy r vai oxy, chi c6 0,000000036g (= 3,6.10-8g) khel luting chat hien thanh nang Wong - sti thay d6i khel Wong nay la ye cling nha ma nhang cal can hien dai nhat hien nay cling khong the phdt hien duoc. Tuy nhien, nang Wong bien clei trong cdc phan ling hat nhan nguyen tit la di]. lan de khol Wong Wen del c6 the do duoc]. - Nha dinh luat bao toan kh6i Wong ma chung ta c6 the can bang cdc phuong trinh hod hoc vb. tinh &toe kh6i. Wong cua cdc chat tham gia phan ling va cdc chat san phdm theo tttdng quan tY' le thuan khi dila vao phuong trinh phan fing da can bang. 19 3.2. Dinh luat thanh phAn khOng d6i cUa Proust (Nha hod hoc ngitai Phap, 1754 - 1826) - Mot hop chat nhat dinh du thick didu chg bang each nao thi van bao g6m ding mot loai cac nguyen to va ding tS7' s6 khoi Wong cua cac nguyen to trong hop chat. Cac kgt qua sau day thu dttoc ve thanh phdn khoi Wong cita cac nguyen to trong 20,0 g calci carbonat: Phan tich theo So phdn khgi Wong khoi ltiong Phdm tram khoi Wong 8,0g calci 0,40 calci 40% 2,4g carbon 0,12 carbon 12% 9,6g oxy 0,48 oxy 48% 20,0g 1,00 phAn khoi 100% kligi Wong Wong Dinh luat thanh phdri khong dgi cho ta bigt rang, calci carbonat tinh khigt thu dttoc tit da hoa ctidng ct mot ngon nUi, tit san ho ngdm &ad bidn, hoac tit bat kS7 mot ngu6n nao khac, thi van tim thay ding cac loai nguyen to tao thanh (calci, carbon, oxy) va ciing ix* s6 plign tram nhti da cho bigt bang tren. - Nhtt vay, nh6 dinh luat thanh phan khong dgi ma m6i hop chat xac dinh &toe bidu thi bang mot tong thiic hod hoc nh'at dinh. Co thd suy ra khoi Wong nguyen to tit tS7 1e khoi lticsng ciia no trong hop chat: Kh6i prong nguyen to = KhCii lacing hop chgt x S6 phgn kh6i Ittong nguyen to 1 phan khoi Wong hop chgt Chung ta c6 thd bidu dign phdn khoi ltiong theo bat kS7 don vi do khoi Wong nao ngu tien dung cho tinh toan. - Cling can chu Sr la thanh phdri khong dgi chi hoan toan diing cho nhfing hop chat c6 khoi ltiong phan tit nhO 6 trang thai khi va 16ng. voi chat ran hoac polymer, do nhling khuygt tat trong mang tinh the hoac trong chai dai phan tit, thanh phdn cila hop chat thttang khong ling dung v6i mot ding thiic hod hoc xdc dinh. Vi du, tY' oxy/titan trong titan oxyd digit chg bang cac phyong phdp khdc nhau dao dOng tit 0,58 dgn 1,33; ding thiic cila sat sulfid c6 thd vigt Fei,S voi x dao dOng tit 0 dgn 0,005; phan tit glycogen trong cac to bao gan va co c6 thd go'm 1000 dgn 500000 don vi glucose; v.v... 20 3.3. Dinh 1u4t tS7 le boi et:1m John Dalton (Nha hoa hoc Anh, 1766-1844) - Neu hai nguyen to A va B ket hop vdi nhau tao thanh met s6 hop chat boa hoc thi cac kh6i Wong khac nhau cua B ket hop voi met khoi Wong co dinh cUa A co the bieu thi dudi dang tY' le cifa cac s6 nguyen nhO. VI du, xet 2 hop chat duoc tao thanh tit 2 nguyen to carbon va oxy, va goi IA carbon oxyd I va carbon oxyd II. as cling nhiet de va ap suat, khoi 1-uong rieng cila I la 1,25 g/1; dia. II là 1,98 g/l. Ngoai ra I la chat dee va de chay; II khong dec va khong chay. Vi day là cac hop chat khac nhau nen thanh phdri kh6i Wong cUa chung ding khac nhau. Ke't qua phan tich cho thay: Carbon oxyd I: 57,1 % kh6i Wong oxy va. 42,9 % khoi Wong carbon. Carbon oxyd II: 72,7 % khoi Wong oxy va 27,3 % khoi Wong carbon. De hieu ro hien Wong tS7 le bOi s6, ta dung % kh6i Wong cifa carbon va oxy trong moi hop chat de tinh ra khoi. Wong cifa cac nguyen to nay trong met khoi Wong da biet, chang han 100g cila hop chat. Sau do la chia khoi Wong oxy cho khoi Wong carbon trong moi hop chat de xac dinh kh6i Wong oxy ket hop \Ted 1 khoi Wong xac dinh cila carbon: Carbon oxyd I Carbon oxvd II g oxy/100g hop chat: 57,1 72,7 g carbon/100g hop chat: 42,9 27,3 g oxy/g carbon: 57, 1 = 1,33 72,7 2,66 42,9 27,3 Chia tY le s6 g oxy/g carbon trong hop chat II cho hop chat I, ta thu difoc: 2,66g oxy/g carbon trong hopcli6tII = 2 1,33g oxy/g carbon trong hop chSt I 1 Dinh luSt tY le bei cho chUng ta bie't rang, trong hai hOp chat duoc tao nen tit ding cac nguyen to, thi so phSn khoi Wong cila met nguyen to so voi met phan khoi Wong cua nguyen to kia phai thay d6i theo nhUng so gia là nhilng so nguyen, cliff khong phai thay d6i met cash lien tuc, ngliia là chat II chila kh6i Wong oxy gap 2 lAn a chat I, cliff khong phai là 1,5 hay 1,7 Fan, hay bat cif met gia tri trung gian nao khac. Neu hai nguyen to tao thanh nhieu hdn hai hop chat, quy lust van dung nhtf vay. VI du, 7 g nits (met khoi Wong co dinh) se ket hop voi nhiTng khoi Wong khac nhau cua oxy de tao thanh 5 oxyd nhtf the hien duoi day: N20 NO N2 03 NO2 N205 g oxy:4g 8g 12g 16g 20g Ts, le nhang s6 nguyen don gian se là: 4 : 8 : 12 : 16 : 20 = 1 : 2 : 3 : 4 : 5 21 3.4. Thuygt nguyen tit cUa Dalton Cdc dinh ludt vg khal ltiOng gitip cdc nha hod hoc ttt duy ve mot mau nguyen tit - bai vi vat chgt ton tai dtioi clang nhung thin vi khong the phd va dttoc, mai don vi c6 mat khaa Wong dac triing. John Dalton la ngtiai tao ra cu clot phd khi Ong trinh bay thuyet nguyen di v8 vat chgt narn 1808. Dalton dtta. ra 1ST thuy& cim minh trong mat chai nhiing die'u dtioc mac nhi8n thita nhan. Nhang dieu do chioc trinh bay 14i dltaii day theo cdc thuat ngfi khoa hoc hien d4i va sap xe-p lai de tien cho viec thao Juan. Nhung not dung trong ngoac chi ra sit khac nhau chi yeu giiia nhang dieu mac nhien thita nhan cila Dalton va nhang hien biet cua cluing ta ngay nay. 1. Vat chdt gom cdc nguyen tit la nhang tieu phan rat nha be khOng the chia cat cilia mat nguyen to. Nguyen tit khong the tao ra hay phd huy (ngay nay cluing ta biet rang nguyen tit khong the chia nha nhiing dttoc cdu tao tit nhang phan tit nha hdn goi la cdc hat dual nguyen tit). 2. Nguyen di ciia mat nguyen to khong the chuyen thanh nguyen tit cim nguyen to khdc. Trong phan -tang hod hoc, cdc chgt ban ddu tdch ra thanh nhung nguyen tit, sau do lai tai ket hop de tao thanh nhang chdt khac (ngay nay cluing ta biet rang trong phan ling hat nhan, nguyen tit cila mat s6 nguyen to cb the chuyen thanh nguyen tit cila nguyen to khdc, nhting di8u nay khong xay ra trong phan itng hod hoc). 3. Nguyen di cila ding mat nguyen to thi Wang tti nhau v6 khol Wong va tinh chgt, nhitng khdc vdi nguyen tit cila bgt kSTnguyen to nao khdc (ngay nay cluing ta biet rang cdc nguyen tit cila mat nguyen to c6 the khdc nhau ve khoa Wong - cdc d8ng vi, nhttng nhin chung sit khdc nhau nay là nh6). 4. Hop chdt dttoc tao thanh tit star ket hop hod hoc cdc nguyen tit cua cdc nguyen to khdc nhau vdi 0 le nhdt dinh (ngay nay chung ta biet rang c6 mat s6 hop chdt c6 sti khdc nhau nha v6 tS71"e' cac nguyen tit cua chung, nhting ctigu mac nhien thita nhan nay ve' co ban van khong thay d6i). Theo nhung mac nhien neu tren, Dalton da giai thich cdc dinh luat ve khaa Wong: - Sit bao than khea Wong. Nguyen di khong the thioc tao ra hoac phd huST' (mac nhien 1) hay chuyen thanh loaf nguyen tit khdc (mac nhien 2). VI mai lo4i nguyen tit c6 mat khoa Wong xdc dinh (mac nhi8n 3), nen trong mat phan ling hod hoc ma CI do cdc nguyen tit dttoc sap x6p lai thi khong the gay ra sut bie'n d6i v8 khol Wong. - Thanh phan khong del Hop chgt la sl.t ket hop cdc nguyen tit theo mat 0 le nhgt dinh (mac nhien 4), m8i nguyen tit 141 cal khea Wong xac dinh (mac nhien 3). Vi va'y m8i nguyen to trong hop chdt luan chie-m pladn co dinh so vol. klai Wong than the. 22 — Ty le bei. Cac nguyen tit cila met nguyen to có ding khoi Wong (m'a'c nhien 3) va khong the chia eat ctuoe (mac nhien 1). Do s6 nguyen tit B khde nhau có the k6t hop vdi mr3i nguyen tit A trong hai hop chit nen t7' . le kh6i. Wong cua nguyen to B k6t hop vdi met khoi Wong xac dinh cita nguyen t6A la met so nguyen nh'6. 3.5. Tranh lulan v6 khoi kiting nguyen tit Dinh lua't Gay-Lussac va Avogadro Sau khi thuy6t nguyen tit ra doi, nhi6u nha nghien citu da c6 gang xac Binh khoi luong nguyen tit cac nguyen to tit tST le khoi Wong cua nguyen to trong hop chit. Vi mei nguyen tit qua nhii be nen ta chi có the xac dinh khoi Wong nguyen tit eila met nguyen to trong hop chit so vdi khoi Wong nhang nguyen to khac. De lam co sd cho nhfing kh6i Wong nguyen tit ttfcing d6i nay, Dalton da an dinh khoi Wong nguyen tit la 1 doi vdi hydro, met chit da bi6t ctitoe ro rang. Trude do Lavoisier da chi ra rang nude Om 8g oxy vdi lg hydro, vi vay Dalton mac dinh khoi Wong nguyen tit Wong doi eita oxy la 8. Tuy nhien, kh6i Wong d6i nay chi dung n6u s6 nguyen tit oxy (trong 8g oxy) bang so nguyen tit hydro (trong lg hydro), theo do met phan tit nude chi Om 1 nguyen tit oxy k6t hop vdi 1 nguyen tit hydro (KST hieu HO). Clang vao thai gian nay, nha hod hoc ngitC:ii Phap Gay-Lussac (1778 - 1850) ti'6n hanh met boat cac thi nghi'em nghien cull v6 tS'r le nguyen tit dm nude. Thay bang viec do kh6i Wong thi 'Ong lai do cac the tich klii hydro k6t hop vdi khi oxy de tao thanh hdi nude. Gay-Lussac thiy rang trong ding di'eu kien nhiet do va ap suit thi di 2 lit khi hydro k6t hOp vita du vdi 1 lit khi oxy de tao thanh 2 lit hdi nude. CUng vdi k6t qua thi nghiem d nhie'u chit khi khac nua da cho phep Gay-Lussac phat bieu dinh luCit 0 le the' tich: Ccic the' tich cUa cac chat khi tham gia phcin a'ng ty le vdi nhau vet ty le vdi the' tich cua cac sin phdm khi tao themh theo nhring so nguyen nhO. K6t hop gia thi6t ciia Dalton v6 thanh phdn cua phan tit nude va dinh luat 6T' le the tich cila Gay-Lussac, ta có cac k6t qua mong doi va k6t qua thue t6 nhit sau: N6u nude la HO: 1 lit khi hydro + 1 lit khi oxy --> 1 lit hdi nitric N6u nitric la H2O: 2 lit khi hydro + 1 lit khi oxy --> 1 lit hdi nitric Thuc t6 la: 2 lit khi hydro + 1 lit khi oxy 2 lit hdi nitric Khi do, hdu beet cac nha nghien citu cho rang tit ca cac nguyen to, bao gom ca hydro va oxy clang khi, de'u ton tai tu nhien ditoi dang cac nguyen tit rieng biet. VI \Tay, k6t qua qUan sat cluoc dm Gay-Lussac to ra khong coy nghia, bai vi nhu the thi moi nguyen tit oxy da chia doi de tao thanh 2 phan tit nUdc. Chinh Dalton da rat phan d6i cac k6t qua va ky thuat do eila Gay-LussaC. 23 — Nam 1811, nha vat lY ngtiai )7 la Avogadro (1776 - 1856) da giai thich dtioc cac tY' 10 don gian giffa cac th0' tich cUa chat khi quan sat thay trong cac phan ling hod hoc, sau khi 'Ong thie-t ldp duoc dinh ludt - Dinh lutit Avogadro: Ccic the tich bing nhau ceza cac chat khi bat k3' le& a cling nhi0 cho va ap sudt cteu cha'a cling mot so-phan tet. Nhu vdy, moi tiL phan khi hydro va khi oxy thuc chgt la mot phan tit g6m 2 nguyen tit. Nhiing phan tit nay, chii khOng phai là nhiing nguyen tit, bi chia ra tang phdn va nhung nguyen tit rieng re sau do mdi tai ke-t hop d0)tao thanh phan tit hoi /tide. VI \Tay, 2 lit khi hydro chfia so tieu phan khi gdp 2 ldn 1 lit khi oxy va ding s6 tie'u phan nhu trong 2 lit hdi rnfoc. Hinh 1.3 minh hoa each giai thich nhfing ldt qua cUa Gay-Lussac theo dinh ludt Avogadro (1.3A cho tao thanh hdi nu& va 1.3B cho tao thanh amoniac). cb 8 • • • • • 1 lit khi hydro 1 lit kill hydro 1 lit hoi nu& 1 lit khi oxy 1 lit hoi nuOc Hinh 1.3A. Cac the tich kgt hop coa hydro va oxy de tao thanh hal nu'dc 8 8 + CO 3 phan tit hydro (3 thd tich) 1 phan tic nito (1 thd tich) 2 phan tic amoniac (2 thd tich) Hinh 1.3B. Cac the tich kgt hop cila hydro va nit° de tao thanh khi amoniac Wac du each giai thich dia. Avogadro la dung, nhung thai do chtta de duoc chap nhdn, bai vi 6ng da dung nhiing thudt ngit kho hiL va phep tinh town phitc tap. Khoang 50 nam sau do ST Wang cila Avogadro mdi dtioc thiia nhdn va dan den vi0c xdc dinh khoi Wong Wong d6i thing dan cua oxy la 16. VI tST 10 khoi Wong cUa nude la 8g oxy vOi. 1g hydro, vdy tsr 10 cUa cac the tich ke-t hop coy nghia la 1 nguyen tit oxy n4ng gap 16 ldn so vdi nguyen tit hydro: 24 (Ty lethe' tich) 1 oxy (16) 16 8 , — = — (ty le kh6i Wong) 2 hydro (1 cho moi nguye n di) 2 1 • Thuyet nguyen tit cila Dalton da giai thich kho'i Wong cua cac nguyen to, cac phan ling theo nguyen tit, thtic day yiec xac dinh khoi Wong cua cac nguyen tit va cac tong Ur& boa hoc (nhu NH3cho amoniac, H2O cho rutoc...) do do cta co anh hitting sau sac den sti Oat trign cua hoa hoc. Tuy nhien, mo hinh nguyen tit Dalton sdm to ra có nhieu han che. NO khong giai thich duoc tai sao cac nguyen to lai ket hop vdi nhau theo nhang tY' le s6 nguyen tit nhat dinh. Chang han cloi vdi phan tit intoc, tai sao lai la 2 chit khong phai la 3 nguyen tit hydro ket hop vdi 1 nguyen tit oxy. Cling nhu vay, cai nhin trOn tria nhtt hon bi cling nhac ve nguyen tit da khong giai thich dttoc hien Wong cac tieu phan -Lich dien trong cac thi nghiem sau dO. Can co met mo hinh nguyen tit phlic tap hon de giai thich so lien ket gifia cac nguyen tit, sit hinh thanh cac ion... Nhitng do la si nghiep ciia the he cac nha khoa hoc tiep theo d nhang nam cu6i the k 'Y XIX dau the k 'Y XX (xem chuong 2: cau tao nguyen tit ya dinh lust tun hoan cac nguyen to). Hinh 1.4 (6 muc 1.5) la khac hoa dai cucing ve cgu tao nguyen tit hien dai. 4. MOT SO DON VI CUA HE SI QUAN TRONG TRONG HOA HOC Tit nam 1960, he don vi qu6c t6 SI (chit vie't tat bat ngu6n tit tie-ng Phap: Systeme International d'Unites) duoc cac nha khoa hoc toan cdu thong nhat sit dung. He SI data tren 7 don vi do luting cd ban, nitii don vi xac dinh mot s6 do chuan cua met dai Wong vat IY (Bang 1.3). Bang 1.3. Cac don vi co ban coa he SI Dai lurIng vat 19 Ten don vi Vigt tit don vi Knell lacing Kilogam kg DO dai Met m Thai gian Giay s Nhiat di) Kelvin K Wong chat Mole mol Cooing di) (Jong din Ampe A Cu'ong do sang Candela Cd Cac don vi khac goi la don vi &an xugt do sit ket hop cUa 7 don vi co ban neu tren. Vdi cac dai Wong nhO hdn hoac lon bon so vdi don vi co ban, ngudi to sit dung cac tigp dau ngit thap phan hay he thong 147 hieu theo ham so-mu (Bang 1.4). 25 Tie-p dgu Ky hieu tigp dgu Bang 1.4. Cac flap Tau ngif thap phan caa he SI Y nghia S6 luji theta Bang s6 Bang chCt tera T 1.000.000.000.000 nghin ti 1012 giga G 1.000.000.000 ti 109 mega M 1.000.000 triau 106 kilo k 1000 nghin 103 hecto h 100 tram 102 deka da 10 mutii 101 - - 1 mot (don vi) 10° deci d 0,1 phan mu'Oi 10-1 centi c 0,01 phan tram 10-2 milli m 0,001 phan nghin 10-3 micro i-t 0,000001 phan triau 10-6 nano n 0,000000001 phan ti 10-9 pico p 0,000000000001 phan nghin ti 1012 femto f 0,000000000000001 phan triau ti 10-15 (Nhieng ti'dp dliu in cki m thu'iing du'o'c dung trong hoci hoc) Met s6 ctdn vi SI quan trong trong hod hoc — Chi& dui: don vi co ban la met (m). Trong eau tao nguyen tie, phan tit thUang clang cdc ctdn vi nho hon nhieu, vi du: micromet (1 1..M1 = 10-6m), nanomet (1 nm = 10-9 m). The' tich: bat kST mau vat chat nao cung có the r la phdri khong gian ma no chiem ch6. Don vi co ban la met khol (m3). Trong hod hoc, don vi quan trong nhat cua the tich la. lit (L) Ira mililit (mL): 1 L = 1 dm3 10-3m3 1 mL = 1 cm3= 10-3dm3= 10-3L = 10-6m3 Khoi lu'o'ng: la s6 luong vat chat trong met vat. Ddn vi cc; ban là kilogam (kg) - don vi co ban duy nhat có met tie-p d'au nga (kilo). Thuat ngil kh6i Wong va trong litong có nghia phan biet. Vi s6 luting vat chat cila met vat khong thay d6i nen khoi lacing là hang so. Trong Wong cila met vat phu thuec vao kh6i luting ciia no va luc but cila truong hap &an tdc dung len no. Do truing hap clan thay d6i theo de cao so vdi be mat trdi dat nen trong luong cila met vat cung thay doi theo do cao (vi du, met vat nhe lion met chUt cJ tren dinh nue cao so vdi tren mat bien; hoac na,ng hdn met chUt khi &at vat d bac clic hay nam cuc so vdi vat. ay dat d xich dao xa 26 tam trai dat hon). Tuy nhien, kh6i Wong duoc xac dinh bang can nen se khong phu thuQc vao truang hap dan, vi cai can dtioc thiet ke de do kh6i e ltiong chit khong phai do trong Wong. Cai can tii Ong so sanh khol. Wong chua biet ciia vat vdi nhung khol Wong da duoc thiet ke ben trong can, nen trUang hap Can tai cho do tac dong len cluing thong duong nhau. Can phan tich dien xac dinh kh6i Wong bang cach tao ra mot dien tru6ng thong lai tnthng hap dan tai ch'6. DQ ldn cila dong dien can thiet se dila dia can ve vi tri 0 r'6i mdi do kh6i luong cila vat. Nhiet ctO: la s6 do mile dQ nong hay lanh cua mot chat nay so vdi chat khac. Don vi co ban la dQ kelvin (K). He tranh nham vdi cac hang s6 can bang K nguai ta ciing viet tat la °K. LAW Y thing nham ve nghia cua hai thuat ngii nhiet (Q) va nhiet do (T). Nhiet la nang Wong truygn gitia cac vat c6 nhiet dQ khac nhau. Nhiet gan lien vdi huong truye'n: nhiet truy6n tit vat c6 nhiet do cao sang vat c6 nhiet dQ thap hon cho den khi nhiet dQ ciia cluing bang nhau (cuc da trong tay ta, cai "lanh" &fang nhtt truye'n sang ban tay, thuc ra la nhiet tht tay ta truye'n sang cue da.). Nhiet c6 U./1h bao quat (nhu the tich chang han), nhung nhiet dQ c6 tinh tap trung (nhu ty trong chang han): mot thang nude soi cluia nhieu nhiet (nang Wong) hon mot c6c nude soi, nhung nhiet dQ ciia cluing bang nhau. Cac thiet bi thong thithng trong phong thi nghiem de do nhiet de) la nhiet no chlia mot chat dich c6 kha nang and Ong khi duoc gia nhiet. Khi bau nhiet ke duoc nhung chim trong mQt -chat nong hon no thi nhiet se truy6n of chat nay qua thug tinh vao chat dich, lam no gian va clang len trong 6ng nhiet ke. Neu chat duoc do lanh hon nhiet ke, nhiet se bi keo ra kh6i chat dich lam cho no co lai trong 6ng nhiet Co 3 thang nhiet dQ hay gap: Celsius goi la dQ bath phan (°C); Kelvin (K) va. Fahrenheit (°F). Don vi co ban cila he SI la. thang Kelvin (cho Y rang, theo quy u6c qu6c to thi Kelvin khong c6 ky hi'eu do (°)). Thang Kelvin goi la thang tuyet d6i duoc ua chuQng hon trong cac tinh toan khoa hoc, mac du chang Celsius cang hay &toe dung; thang Fahrenheit con hay sit dung d Hoa K. Ba thang nay khac nhau ve dQ ldn cua dQ va/hoac nhiet dQ cila diem 0 (zero). Thang Celsius (Moe dung tii the kY XVIII do nha thien van hoc Thuy Dien Anders Celsius (1701 - 1744) de xuat, data tren su thay dOi tra.ng thai vat lY dia nude: 0°C la diem bat, dau dong bang dia nude va 100°C la diem soi cua no ap suat khi quyen binh thuong). Thang Kelvin (tuyet dol) do nha vat lY Anh William Thomson, con dtioc biet vdi ten Lord Kelvin (1824 - 1907) de xuat nam 1854, c6 ding dQ Ion v6 dQ vdi thang Celsius, nghia la de bang 1/100 cUa khoang gifia diem dong bang va diem soi cua nude, nhung khac nhau v6 di6m 0 (zero). Nhiet dO.s6 OK (dO 0 tuyet d6i) là -273,15°C, vi the nude dong bang a 273,15 K (0°C) va soi d 373,15 K (100°C). Vi vay, cach chuyen doi gifia hai thang Celsius va Kelvin nini sau: T (K) = t (°C) + 273,15 (1-3) t (°C) = T (K) — 273,15 (1-4) 27 Thang Fahrenheit khdc hai thang kia d diem 0 va do lon cua clO. Nu & &rig bang d 32°F va soi a 212°F. VI the, 180°F (212°F - 32°F) dai din cho ding mot su thay doi nhigt dO Wong -tang vdi 100°C (hay 100 K), vay: 1 oc = '180\ o9 (1-5) 100, = °F = 1,8 °F 5 He chuyen thanh °F, trttOc tien chuydn do lOn ciia do va sau do digu chinh diem 0: (oF) 9 tcc) + 32 5 (1-6) chuyen °F thanh °C, tilt& het digu chinh diem 0 va sau do digu chinh He do lon dm do: t (°C) = [T (°F) - 32] x -5 (1-7) 9 (Chi có duy nhat mot nhiet do ma tai do 2 thang Celsius va Fahrenheit triing nhau la -40°, nghia la. -40°F = -40°C). * Bai tap van dung: Than nhigt cita met dila tre do duoc là 101,7°F. a. Neu than nhigt binh thuang la 37°C, vay dila tre cif) bi sot? b. Nhigt do cila dila tre do theo do Kelvin la bao nhieu? Giai: a. Chuyen nhigt do tit °F sang °C theo phuong trinh (1-7): t (°C) = [101,7 - 32] x 5/9 = 38,7 °C Vay, dila tre bi sot (vi than nhiet cao hdn 37°C). b. Chuyen tit °C sang K theo phttong trinh (1-3): T (K) = 38,7 °C + 273,15 = 311,8K Vay, nhang dila tre có than nhigt 311,8 K phai xem la bi sot. - Thai gian: don vi co ban la gidy (s). Hien nay thai gian duoc do chia tren tieu chuan nguyen tinh theo su phat xa vi song tit nguyen tit cesium (Cs) bi kith thich. MOt phan ling hod hoc nhanh xay ra trong vai nano giay (10-9s), trong khi nhiing phan ling cham, nint qud trinh gi cua sat hay stl gia sinh hoc c3 nguai, xay ra trong thai gian dai duoc do bang thdng, nam. Nhigu nha hod hoc hign clang diing tia laser de nghien citu nhfing bier' d6i hod hoc xay ra trong vai pito giay (10' s) hoac tharn chi chi vai femto giay (10' s). 28 5. SO HIEU NGUYEN TLS, SO KHOI, KY HIEU HOA HOC — Hinh anh dai Wang v6 nguyen tit hien dai dUcic the hien 6 Hinh 1.4. Vung chiem cif bcii electron dien tich am Khoang 10'' m Hat nhan A Nguyen to Proton (then tich &rang) Neutron (,khong dien tich) Khoang 10" m B Hat nhan Hinh 1.4. Cau tao dai cu'ong cOa nguyen tit hien nay A. Mot may cua cac electron tich dien am dang chuyen clang nhanh va chiam cif hau nhtt town ba the tich nguyen tit va xung quanh mat hat nhan rat nh6 be nam 6 trung tam. B. Hat nhan mang hau nhu' town ba khai luting cOa nguyen tit, g6m cac proton tich dien du'ang va neutron kh6ng dien tich. Kich thu'Oc hat nhan v6 cung nha [neu phang to duting kinh hat nhan bang khoang 1 cm, nhu' hinh ye a day, thi eluting kinh nguyen tit se khoang 100 m - dai han mot san bang dab — Bang 1.5 tom tat dac trting oda cac hat dtioi nguyen tit có trong nguyen tit cac nguyen to. Bang 1.5. NI-Ong dac cua cac hat ca b5n tao thanh nguyen tit Ten (Ky hieu) Dien tich Kh6i Wong Vi tri trong nguyen tit Tilting d6i Tuyet d6i Tilting d6i Tuyet d6i Proton (13+) Neutron (no) 1+ 0 1,602 x 10-19C• 0 1 1 1,673 x 10-24 g 1,675 x 1024 g Hat nhan Hat nhan 1— Electron (e-) -1,602 x 10-19 C 1/1837 9,109 x 10-28g hat nhan (* Culong (C) la don vi dien tich cua N SI) - So- hieu nguyen (Z) cua mot nguyen to bang s6 proton trong hat nhan cua moi nguyen tit cua nguyen to do, va khac s6 hieu nguyen tif cua cac nguyen to khac. Z ciing bang s6 electron trong nguyen tit va bang so this 29 tai cua nguyen to trong Bang tun hoan. Vi du, tat ca cac nguyen tit carbon (Z = 6) c6 6p+, 6 electron va la nguyen to this 6 trong Bang tudn hohn; cac nguyen tit oxy (Z = 8) c6 8p+, 8 electron va la nguyen to this 8 trong Bang tun hoan v.v... — So kit& (A) là tong se; cac proton (Z) va cac neutron (N) trong mot nguyen Vi m6i proton ho4"c moi neutron c6 khoi luong xgp xi bang met ddn vi khgi luting nguyen tit, nen: A = Z + N (1-8) c6 gia tri gdn dung (hoac tri s6 da chick lam trop) cUa khollUOng nguyen tii (c6 thg b6 qua kh6i Wong cila electron vi no rat nhO, chi bang 1/1837 kh6i luting dm proton ho4c neutron). VI du, hat nhan cila carbon c6 6 proton va 6 neutron, nen s6 kheci A hay kh6i Wong nguyen tit dia carbon bang 12; mot nguyen tit uranium chlfa 92 proton va. 146 neutron trong hat nhan nen se; khol A hay kheci Wong nguyen tii dm uranium la 238. KY hieu nguyen tit (hoc kY hieu nguyen to): m6i nguyen to c6 mot kST higu theo ten goi tigng Anh hoac tigng Latin hoac Hy Lap cila no, chang han C cho carbon, 0 cho oxygen, S cho sulfur (luu huSmh)... Nguai to ghi them sec khea (A) phia tren va so-proton (Z) phia diidi vao ben trai cua kST higu nguyen to. Muein tim se; neutron ciia hat nhan thi do2i ye phuong trinh 1- 8 a dUcic N = A - Z. Vi du, nguyen tit clor &toe kST higu -; Cl, vay A = 35, Z = 17 va N = S6 khe.ii (p+ + n°) So hiOu --- nguyen tit (13+) MOt nguyen ti! carbon - 12 t? Mot nguyen tit oxy - 16 Mot nguyen ti:( uranium - 238 KS/ hiOu nguyen tit 35 - 17 = 18. Hinh 1.5 minh hoa cach bigu thi chung cho nguyen tit X bat kST va rieng cho ba nguyen tif cu thg. Hinh 1.5. Cach bigu thi nguyen cua cac nguyen t6 6. HONG VI VA KHOI LONG NGUYEN TU' CUA CAC NGUYEN TO 6.1. Diing vi Cac nguyen tit cua mot nguyen to khong hoan toan d6ng nhgt v6 kh6i Wong. TA ca cac nguyen tif carbon c6 6 proton trong hat nhan, nhttng chi 30 98,89% s6 nguyen tit carbon ton tai trong thien nhien c6 6 neutron (A = 12), con 1,11% co 7 neutron (A = 13) va 8 neutron (A = 14). Ccic ddng vi cita mot nguyen to let nhiing nguyen tit' co so-neutron khcic nhau vet do do kit& nhau ve so khoi. Carbon có 3 thing vi 12C,13C, 14C ton tai trong thien nhien va 4 d6ng vi 10 c, 11c, 15C va 16 C dtioc sinh ra trong cac hien dtli hat nhan. Tat ca 7 d6ng vi cua carbon deu có 6 proton va 6 electron, chi khac nhau s6 neutron. Tinh chgt hod hoc ciia met nguyen to ye cd ban duoc quygt dinh bai s6 electron, do do cac thing vi c6 hau het cac tinh chgt hod hoc giong nhau. 6.2. Khici hicing nguyen tit Vi kh6i Wong nguyen tit vo ding nh6 nen khong the do bang cac don vi kh6i luring thong thttang. Moi do Wang can phai có chuan do. Chudn khoi nguyen hien nay la nguyen tet carbon - 12 (12C) va khoi luring cua no du oc quy dinh chinh xac la 12 don vi khoi Wong nguyen tit. Nhtt vay, ddn vi khoi lu'dng nguyen let 1112 khoi lu'dng cua mot nguyen carbon - 12 (tam quy uric viet tat la: dv12C). Theo chuan nay, mot nguyen tit 1H có kh6i luong 1,008 dv12C; not cach khac, mot nguyen tit 12C co khoi Wong lon hdn gam 12 lan khoi Wong cua mot nguyen tit 1H. Gan day nguai ta de nghi goi ddn vi khgi Wong nguyen tit (dv12C) la Dalton (D), theo do mot nguyen tit 12C có khoi Wong 12 dalton (12 D). 6.3. lihoi hidng nguyen tit dong vi va khoi hicing nguyen tit cua nguyen to. Cac di3ng vi cua mot nguyen to &foe xac dinh bang kh6i pho (mass spectrometry), mot philong phap do cac khoi lung Wong d6i cua cac tieu phan trong mot mau rat chinh xac. Vi du, sit dung may khoi phO, chimg ta do thick tY' s6 kh6i lung gala nguyen tit 'Si va 12C la: Kh6i luring cua nguyen tir 28Si = 2,331411 Kh6i luring cua chuan 12 C Tit tS'T s6 kh6i Wong, ta tim thgy khgi Wong dtIng vi cua nguyen tit 'Si so voi &sing vi chuan carbon - 12: Kh6i Wong d6rig vi cua 'Si = Ty so khoi hiring do dttoc x Khoi luring cua 12C = 2,331411 x 12 dv12C = 27,97693 dv12C May khgi pho7 có the do duoc hop phan cua nC6i thong vi trong mot mau nguyen to. Cach do nay la pinking phap de tim khoi Wong nguyen tit cua mot nguyen to. \Tay, khoi lu'dng nguyen tt'z' cua mot nguyen to let gid tri trung binh cac khoi lu'dng czia cac ddng vi nhien ceict nguyen to do. 31 * VI du: Bac (Ag; Z = 47) có 16 d6ng vi, nhitng chi có 2 ct6ng vi 107Ag va 1-(19Ag ton tai trong thien nhien (s6 con lai la quan sat ditoc trong phong thi nghiem d cac bie'n d6i hod hoc khdc nhau). Cac s6 lieu cho bi6t tit may kh6i pho nhLt sau: D6ng vi Khoi Wong (dv 12C) Ty le phan tram (%) trong mau io7Ag 106,90509 51,84 losAg 108,90476 48,16 Vdy: voi IwAg: Phan khoi ltiOng nguyen tit = Khoi litOng ang vi x T le trong mau 106,90509 dv12C x 0,5184 = 55,42 dv12C vdi 1°9Ag: Phdn kh6i Wong nguyen tit = 108,90476 dv12C x 0,4816 = 52,45 dv12C Tit do tim thay khoi It nguyen tit ciia bac la: Kh6i Wong nguyen tit cua Ag = 55,42 dv12C + 52,48 dv12C = 107,87 dv12C Ke't qua nay dude ghi vao Bang tun hoan cho nguyen to Ag. VI du vita neu co tam quan trong de hie'u thau lido rang, khong có mot nguyen tit bac rieng le nao cua kim loaf bac lai có kh6i Wong dung bang 107,87 dv12C. Song, de tinh toan trong nghien citu, chting ta xem nhu' nguyen togo'm ccic nguyen eó khoi trung birth tim thdy (vi du, Ag = 107,87). - Khoi phan mot chat la khoi Wong cria mot phan tit chat do tinh bang dv12C va bang tong kh6i Wong cdc nguyen tit ciaa cdc nguyen to co trong phan tit. VI du, phan tit H2O có khoi Wong phan ta bang 18,015 dv12C, ciia glucose 061112o6la 108,6 dv12C. (chil Y: thuang ngtfai ta khong ghi kern khoi Wong nguyen tit hay phan tit chit dv12C, nhttng ta luon phai hidu la tinh theo don vi do). 7. MOL (vik Vat ciia Mole là mot trong 7 dein vi cd ban ciia he SI) - Dinh nghia: mol la Wong chat chita s6 phan tit ding cau true (nguyen tit, phan tit, ion, dein vi tong thitc) bang s6 nguyen tit trong chinh xdc 12g carbon - 12. SS nay dude goi la s6 Avogadro, do la con so khong 16: 1 mol chita 6,022.1023phan tit ding call true (voi 4 chit s6 có nghia). VI vdy, 1 mol cdc nguyen tit carbon - 12 chita 6,022.1023nguyen tit; 1 mol phan tit H2O chita 6,022.1023phan tit va 1 mol don vi tong thitc NaC1 chita 6,022.1023don vi tong thitc. Ngitai ta ding not 1 mol electron chita 6,022.1023electron; 1 mol proton chita 6,022.1023proton; 1 mol anh sang chita 6,022.1023photon. 32 Luring chat tinh theo mol chi dung cho cac hat vi mo va can chi ra chinh xcic ddn vi caa trice cu the' la gi. VI du, can phan biet mol nguyen tit Cl, mol phan tit C12va mol ion hoac mol don vi ding thitc (lien kdt) C—C, mol don vi ding thac (lien kdt) C=C va mol don vi cong thitc (lien kdt) [Khong the dung khdi niem mol cho cac vat the binh thitang vi se titling diking vOi mot Wong chat lon kilo Wang Wong. Vi du, 1 mol cia cac dau cham (.) xep gdn nhau se dai bang &tong ban kinh cua dai ngan ha; 1 mol cac hOn bi thug tinh ma tre con chili ciao xdp chkg sit len nhau se vai lap ca dien tich chau Au di 6i do sau 62 dam x 1,61 km/dam 100 km!]. Met mol tieu phan caa met chat da bidt có met kh6i Wong xac dinh. VI khoi long nguyen tit la co dinh, mol cho to cdch xdc dinh s6 nguyen tit, so phan tit hay cton vi cong thitc trong mot mau khi dem can. 16i vOi nguyen to, can nh6 2 diem da neu phia trit6c: Kho'i Wong nguyen tit cua mot nguyen to la s6 trung binh can ditoc caa cac khoi Wong cac clung vi tit nhien cua nguyen to do. De tier: hanh can &toe, tat ca cac nguyen tit caa met nguyen to dude xem la có ding khoi Wong nguyen tit. Nghia la, tat ca cac nguyen tit lttu huSTnh deu có khoi Wong 32,07 dv12C; tat ca cac nguyen tit sat deu co khoi laong nguyen tit la 55,85 dv12C; v.v... M6i quan he chi yeu gicia khoi Wong cila met nguyen tit va khoi Wong caa 1 mol nguyen tit do, la: khoi luring nguyen mot nguyen to du'dc biea thi bang dv12C c6 cling gici tri ve so-vol OA lacing mol nguyen tic' cua nguyen to do dude biea thi bang gam. Dieu nay co nghia la mot nguyen tit Wu huynh co khoi litOng 32,07 dv12C, va 1,mol nguyen kw huSrnh co kh6i Wong 32,07 gam. Titling tit, met nguyen tit sat c6 kho'i Wong 55,85 dv12C, va 1 mol nguyen tit sat c6 khoi Wong 55,85 gam. Tit do co the suy ra, 1 nguyen tit lau huSTrih nang bang 32,07/55,85 nguyen tit sat, va. 1 mol nguyen tit li.tu huSTnh nang bang 32,07/55,85 met mol nguyen tit sat. Ddi vdi cac hdp chat m6i quan he cang Wong khoi luring phan tet cact mot hdp chat biea thi bang ctv'C bang ve mat so-vdi khoi luring 1 mol czia hop chat-d6 bieu thi bang gam. Vi du, khoi Wong phan tit nit& la 18,02 dv12C, vb. 1 mol nitric (6,022.1023phan tit) co khoi litong 18,02 gam; khoi Wong phan tit caa NaC1 la 58,44 dv12C, va 1 mol NaC1 (6,022.1023don vi ding thitc) có khoi Wong 58,44 'gam. Mol la don vi rat hail ich vi no gan lien s6 Wong cac phdn tit hod hoc ding ca.'-u true vOi khoi Wong caa met mdu caa cac phdn tit nay. [MOt ngithi bdn hang khOng the tinh 1 td tritng bang each can vi cac qua trang c6 khoi Wong khdc nhau. Ngitoc lai, met nha hod hoc c6 the thu &toe 1 mol nguyen tit d6ng (chlia 6,022.1023nguyen tit), hay bat kST met tST le nao caa con s6 ay, chi don gian bang cach can 63,55 gam dtIng, hay bat kS7 met CST le nao caa khoi Wong 'ay]. 33 Mat khac, cluing to ca the sit dung mai quan ha not tren da tInh kh6i lacing bang gam cila mat don vi khoi Wong nguyen tit: 1 dv'2C . 1 nguyen tit 12C x 1 mol 12C x 12g 12 6,022.1023nguyen tt7t '2C 1 mol '2C = 1,661.1024gam Va vi the, s6 Avogadro cila don vi kh6i Wong nguyen tit la hiOng chat c6 kh6i Wong 1 gam: (6,022.1023dv12C) x (1,661.1024g/dv12C) = 1,000 gam * Chuyan khoi Wong va so/Wong ra mol Kh6i Wong mol (kST hiau M) cua mat chat la khoi Wong cila 1 mol phdn tit ding cau trtic (nguyen tit, phan tit, ion, don vi ding thitc) cila chat do va c6 don vi la g/mol. Chang han khoi Wong mol cua sat la 55,85 g/mol, cUa ntt6c la 18,02 g/mol. Bang 1.6 tang kat cac thuat ngit biau thi kh6i Wong nguyen tit va thang do 16n hon. Bang 1.6. T6ng kgt cac thuat khOi lacing Thuat ngil Binh nghia Dan vi dv12C Kh6i !Vona dongvi - Kh6i lu'ong cita mot dung vi cita mot nguyen to (bon vi kh6i IVong nguyen tit) Kh6i krong SO trung binh dia cac khoi Wong cim cac d6ng vi On dv12c nguyen tit tai tv nhien cita mot nguyen to Kh6i lu'ong TOng cac kh6i Ivong dm cac nguyen t1t (hoac ion) dv12c phan tit trong mot phan tit (hoac trong don vi cong th(tc) Khoi lu'ong ciia 1 mol cita cac phan tit hoa hoc ding KhOi ktong mod (M) cau truc (cac nguyen tit, cac phan tit, cac ion, cac don vi cong thk) Chu 31: Tgt ca cac thuat ngit deu data tren chuan carbon - 12: g/mol 1 don vi khoi Wong nguyen tit (dv12C) = 1/12 khoi Wong Gila. 1 nguyen tit '2C Gia tri khoi Wong ghi trong Bang tuan hoan la khang don vi, vi d6 la kh6i Wong nguyen tit taring doi cho bai. kh6i Wong nguyen tit cila mat nguyen to so v6i 1/12 khoi Wong cim 1 nguyen tit I2C: Khoi lacing nguyen tir turong d6i Kh6i lacing nguyen tir (dv12C) 1/12 kh6i ltto'ng cua I2C (dv12C) Ngay nay, dai Wong mol duoc thay the cho nguyen tit gam, phan tit gam, ion gam vi d6 la dai Wong tang quat hon Mol la don vi cho phep tInh dttoc khoi Wong hay s6 Wong cac phdn tit hoa hoc ding eau trUc trong mat mall vat chat cho tru6c. Nguoc lai, biat khoi Wong 34 hay s6 Wong phan tit hod hoc ding call true cita mot chat cho tilt& ta tinh &toe s6 mol. Co the vigt ra mot s6 cong that duoi day: mol) Kho'i Wong (g) = SO' mol x S6 gam (cud. (1-9) 1 mol S6 mol = Khol W 1 mol ong (g) x (1-10) S6 gam (ciia mol) 6,022.1023phdn tir ding u trc trot S6 phan tit ding cau true = S6 mol x (1-11) 1 mol S6 mol = SO' phan tit ding egu true x 1 mol (1-12) 6,022.1023phdn tir cling au true * VI du van dung 1: a) Co may gam bac (Ag) trong 0,0342 mol Ag? b) Co may nguyen tit Ag trong 0,0342 mol Ag? Giai: a) Vd.n dung ding thitc 1-9, ta có: 107,9 g Ag KhCii luong (g) Ag = 0,0342 mol Ag x b) Vdn dung cong thitc 1-11, ta có: 1 mol Ag = 3,69 g Ag nguyen tir Ag S6 nguyen Ag = 0,0342 mol Ag x 6,022.102' 1 mol Ag = 2,06.1022nguyen tit Ag * Vi du van dung 2: có bao nhieu nguyen tit sat (Fe) trong mot mdu sat ro.ng 95,8g? Giai: Vdn dung ding thitc 1-10, ta ditoc: Fe mol S6 mol Fe = 95,8 g-Fe x 1 = 1,72 mol Fe 55,85 g-Fe Vdn dung cong thitc 1-11, ta có kgt qua: So nguyen tir Fe = 1,72 mol Fe x 6'022.10' nguyen to Fe 1 mol Fe = 1,04.10' nguyen tit Fe * VI du van dung 3: Mangan (Mn) la nguyen to chuyen tigp, thigt ygu cho su truing thanh cua cdc xtfOng. Kho'i Wong ciia. 3,22.1020nguyen tit Mn la bao nhieu? (Day la sec Wong nguyen tit Mn can de xay dUng 1 kg xttOng ngtfai du ran chic). 35 Giai: Ket hop cong thlic 1-12 va 1-10 ta tim throe ddp so: Khi prong (g) Mn = 3,22.1020 x 1 mol Mn X54,94 g Mn = 2,94.102 g Mn 6,022.1023 nguyen tirMn1 mol-Mn- * VI du van dung 4: kho'i hiOng mol caa mot hdp chdt la tang cac kho'i Wong mol cua cac nguyen to c6 trong cong al& hod hoc. Tit do, ta c6 cac thong tin dinh Wong theo ding thirc cila glucose (C6H1206) dtrOc the hien '6 Bang 1.7. Bang 1.7. Th6ng tin chaa tong cong thut hoa hoc dm glucose C6H1206 (M = 180,6 g/mol) Carbon (C) Hydro (H) Oxy (0) SO nguyen to/phan tif dm hop chat 6 nguyen tit 12 nguyen tit 6 nguyen tit S6 mol nguyen tit/mol cila hOp chat 6 mol nguy8n tit 12 mol nguyen tit 6 mol nguyen tit S6 nguyen tillmol cua hop chat 6.(6,022.1023) 12.(6,022.1023) 6.(6,022.1023) nguyen tit nguyen tit nguyen tit Kh6i luting/phan tir coa hop chat 6.(12,01 dv12C) 12.(1,008 dv12C) 6.(16,00 dv12C) = 72,06 dv12C = 12,10 dv12C = 96,00 dv12C Kh6i lu'ong/mol ciia hop chat 72,06 g 12,10 g 96,00 g Qua cac vi du neu tren, ta lttu Sr: + KhOi Wong cua mot m'au va so phdn tit ding cdu true ma no chira deu c6 lien he true ti6p vdi mol nhung khong c6 lien he vdi nhau. Vi vdy, de chuyen doi gifia chung, truck het phai chuyen sang so mol. + Khi giai quye't nhung van de lien quan den moi quan he: kho'i Wong - mol - so phdn tit, chung ta sit dung: — KhOi Wong mol (M tinh theo g/mol) de chuyen gala mol va kheci luong. — SO Avogadro (6,022.1023nguyen tit/mol) de chuyen gitta mol va se)" nguyen tit 8. CAC DINH LUAT VE TRANG THAI KHi LY TU'ONG - THE TICH MOL CUA CAC CHAT KHI — Khi VT Wang (phan tit la chdt diem, gift cac phan tit khong c6 Wong tdc) c6 cac tinh chdt tuan theo phirong trinh trong thdi cila Clapeyron - Mendeleep: PV = nRT (1-13) vdi P la dp sudt kill; V - the tich T - nhiet do thang Kelvin; R - hang se khi; n - so mol khi. Nhi6u khi tlruc n6ng dO thing dOi lodng va d dp sudt, nhiet do khong qua xa diet' kien thtrang cling co tinh chdt tuan theo phirong trinh tren. Tit dinh luat chung theo phtiong trinh 1-13, c6 mot s6 trtiong hop rieng khi hai thong so/trang thai duoc c6 dinh. Khi T va n = const (Dinh luat Boyle) thi: PV = nRT = const 13/ hoa.c P1V1= P2V2, tit do V2= V1x (1-14) P2 day, P1, V1 16. nhang gia tri ddll P2, V2 la nhang gia tri cuOi Khi P va n = const (Dinh 1u4t Charles) thi: ✓ nR — = = const V1 T P hoac V2 ,tit do = V1x T V2 2 (1-15) T1 T2 Ti o day, T1la nhiOt dO d'au; T2là nhiOt do cuoi Khi V va n = const (Dinh luat Gay - Lussac) thi: P nR — = = const T V ho4c PI = P2 , tit do P2= P1x T2 (1-16) T2 T1 Khi P va T = const (Dinh luat Avogadro: O dp suat va nhi4 dO nhat dinh, nhang th4 tich bang nhau cua moi chat khi de'u chita ding mot s6 pha.n tit), vay: ✓ RT = const n P V1 V n hoac = 2,tit do V2= V1 x 2 (1-17) n1 n2 n i Chu y: hang so- khi. R trong phtiong trinh trang thai cila khi 1ST Wang c6 cac gia tri bang so- khac nhau tuST thuOc vao don vi tinh caa P, V, n va T. VI du, 6 di6u kin chuan \Tali T = 273,15°K (0°C) va 1 atm (760 Tor hay 760 mmHg), thi: R = = = 0,08206 PV 1 atm x 22,414 L atm.L nT 1 mol x 273,15 °K mol.°K Hoac trong cac don vi kh6.c dm P hoc V thi R c6 nhiing gia tri bang so voi cac don vi la: 37 mmHg.L mmHg.mL R = 62,36 R = 62400 mol.°K mol.° K R = 8,314 J R = 1,987 cal mol.°K mol.°K Thg tich mol cua cac khi: tit dinh luat Avogadro c6 thg suy ra rang, mot mol cua bat kST khi nao (don chat, hop chat, kg ca h6n hop khi) dgu chigm mot thg tich nhti nhau dual ding digu kign ap suat va nhiet dO. O digu kien tieu chuan, the tich ay la: nRT 1 mol x 0,08206 Eatm/mol.° K x 273,15 °K Vo— P 1 atm = 22,4 lit (chinh xac la 22,414 L). Thg tich nay duoc goi la thg tich mol tieu chuan caa khi. * Dinh luat Dalton vg Ai) suat rieng phdn Ap suat toan phdn cua mot hem hop khi khong toting tac vdi nhau la tong cac ap suat rieng phdn caa m61 khi: Prong = P1 + P2 + + Pi (1-18) Goi nila so mol caa khi i trong h6n hop. Vay; tong s6 mol khi caa h6n hop la: k n = ni i=1 Nha dinh haat Dalton, ta c6 thg thay n va nivao pinking trinh trang thai khi 1ST Wang (phuong trinh 1-13) dg thu dUoc: Pt6ng = k En. RT (1-19) V i=i RT va Pi = ni (1-20) V 6 day, Pto,„gla ap suat chung cita h6n hop khi; V la thg tich chung cila hein hop do; Pila Ala suat rieng phdn caa khi i trong h6n hop. Lap tST s6 gifia Piva Pt6ng, ta c6: Pi Prong n k = Ni (1-21) En i i=1 Rut ra: Pi = Ni•PttIng (1-22) 38 day, NT;la neng do phdn mol cira Mai i trong hen hop. Vdy, cip sudt rieng plain dm mos khi ty le vdi tieing ct6 phcin mol ceta no trong hon 9. DU'ONG LU'gNG Tit dinh ludt thanh phdn khong d6i ta thy rang cac nguyen to ke't hop vdi nhau theo cac tY' le ye Wong xac dinh nghiem ngdt. Do do, ngtkdi ta dua vao hoa hoc khai niem daring Wong, Wong tai nhii khai niem khoi Wong nguyen tit va kh6i Wong phan tit. * Dinh nghia: Thuc nghiem hod hoc xac dinh rang: 1,008 khoi Wong hydro tac dung visa du vdi: 8,0 kh6i Wong oxy de tao thanh nude (H2 0) 35,5 clo hydro clorid (HC1) 23,0 natri natri hydrid (NaH) 16,0 huynh hydro sulfid (H2S) 3,0 carbon metan (CH4) v.v... S6 phdn khoi Wong ma cac nguyen to tac dung visa du vdi 1,008 phdn khoi Wong hydro lai tac dung visa du vdi nhau de tao thanh cac hop chdt khad. VI du: 8,0 khoi Wong oxy + 3,0 kh6i Wong carbon carbon dioxyd (CO2) 35,5 kh6i Wong clor + 23,0 khoi luring natri --> natri clorid (NaC1) 16,0 khol. Wong litu huynh + 3,0 khoi hiring carbon --> carbon disulfid (CS2) v.v... Nguei ta goi s6 phdri kh6i luring ma cac nguyen to tac dung visa du vdi 1,008 phdn kh6i Wong hydro (va lai tac dung vita du vdi nhau) la diking Miring cua cac nguyen to, kS7 hieu là E (equivalence), va EH= 1,008; E0= 8; Ec1= 35,5; Es= 16; v.v... chu ST rang, during hiring la s6 phdn khoi hiring hiring diking giiia cac,chdt trong phan ling nen có the sit dung bdt din kh6i Wong nao'de bieu thi no (mg, g, kg...). Do chinh tit khai niem &tong Wong neu tren ma viec xac dinh diking hiOng cua mOt, nguyen to hay oda met hop chdt khong nhdt thiet phai xudt phat tit hop chdt caa chling vdi hydro. VI du, de tim diking Wong clia kern (Zn) khong the xudt phat tit phan ling cila kern vdi hydro, vi ci dieu kien thueng phan sing nay khong xay ra. Tuy nhien, thtic nghiem de" clang cho thdy: 32,5 khoi Wong kern tac dung vita du yeti 8 khoi Wong oxy (1E0) de tao thanh kern oxyd (ZnO), vdy, Ezn= 32,5. Hoc de tim daring Wong H2SO4khong the bang cach cho acid nay tac dung vdi hydro bode oxy, nhting thitc nghiem cho big: 49 39 khoi Wong H2SO4tacdung visa du v6i 32,5 khoi luting kern (1Ezn), vay EB2so, = 49. Tit day, có the diia ra dinh nghia chung cho during hiong: Duong Wong cua mot nguyen to hay hop chat la so phdn khoi Wong cila nguyen to hay hop chat do kk hop hoac thay the vita du v6i 1,008 phAn khOsi Wong hydro hoSc 8 phdn khol. Wong oxy hoac voi mot &long Wong cila bat liST chat 'rho khac da bie't. - Trong thilc t6 ngtiai ta thuang dung &icing luring gam, vdi quy Dating Wong gam dm mot chat là Wong chat do duoc tinh bang gam va có tri s6 bang &icing long cila no. Nhii \Tay, EH= 1,008 g ; E0= 8 g ; ENa = 23g Ezn = 32,5g ; Er-129:1)4' 49g Dinh lust &tong Wong cila Dalton: Cac chat tac dung vdi nhau theo cac khoi Wong tS7' le veil duong liking cua chung. Noi each khac: so during hiring cua cac chat trong phan iing phai bang nhau. Dinh lust duoc the hien qua he thfic don gian: hoac m • E • = A M A mB EA EB (1-23) mB EB 6 day: mtA, mB la khoi luting tinh bang gam caa chat A va chat B trong phan ling EA, EBla &long Wong gam cila chat A va B Dinh luSt &long Wong cho phep Ur-1h khoi Wong mot chat trong phan itng n6u bie't &tong hiong cua cac chat va khoi Wong tac dung cila chat kia. VI du, tinh khooi tong khi clor tac dung het v6i 3,45g natri, bie't ENa = 23; Ea = 35,5. Ap dung pinking trinh (1-23) c1.6 clang tim thay: 3,45g _ m0 3,45g x 35,5 = = 5,33g 23 - 35,5 23 Voi khai them ndng dd during luring là so-chicing lu'o'ng gam chdt tan có trong 1 lit dung dich (14 hieu N vie't sau tri s6 during Wong), dinh luSt &tong Miring duoc sit dung rSng raj trong phep phan tich chuan dS. Chang han, can bao nhieu ml dung dich kiem B Oat la VB) de trung hos het VAml dung dich acid A do nemg dO daring Wong la NA. Bik ang dS &icing hiring clia dung dich kiem B la NB. Ap dung dinh it* during Wong: s6 during Wong cira cac chat trong phan itng phai bang nhau, ta co: VA VB V x N 1000 x NA - 1000 x NB VB = N A (1-24) B 40 Phvong trinh (1-24) dvoc dp dung cho tat ca cac phvong phdp phan tich the tich (phvong phdp acid - base; phtiong phdp ket tiia; phtiong phdp phlic chat; phvong phdp oxy hod - nghia hod hoc dia khdi niem du'o'ng lacing lien quan trvc tiep den khdi niem hod tri cua cac nguyen to. Trude day, nguai ta coi hod tri la kha nang cad mot nguyen tit elm nguyen to c6 the ket hop hoac thay the bao nhieu nguyen tit hydro hoac bao nhieu nguyen tit khdc tildng vay, daring lu'dng cua mot nguyen to so do'n vi khoi lacing (so-phan khoi lacing) cUct nguyen to Cry taring rang vdi mot do'n vi hod tri. Gina &icing luting (E), hod tri (n) va khoi ltiong nguyen tit (A) cila nguyen to c6 mei taring quan sau: E = A (1-25) n VI du, oxy c6 hod tri 2, kh6i Wong nguyen tit 16, nen: Eo= —16 = 8 2 Neu nguyen to c6 nhieu hod tri thi during ltiong ciia no ciing thay d6i tuST thu6c vao hod tri ma no the hien trong sari pham tao thanh sau phan ling. Vi du, carbon c6 hod tri 2 va 4. ei phan ling: 2C + 02= 2CO, carbon the hien hod tri 2, nen Ec= 12 = 6. COn d phan ling: C + 02= CO2, carbon the hien 2 hod tri 4, nen Ec= 12 =3. 4 Mo rOng khdi niem dtiong Wong cho cac hop chat, ta van nhan ray nghia hod hoc cVa no la phan kh6i lvong ttidng iing vdi mot don vi hod tri ma hOp chat dem trao d6i hoac ket hop vdi cac hop chat khdc trong phan ling. Chang han H3PO4= 98. Neu trong phan ling, phan tii H3PO4chi trao d6i 1 proton, hop chat dvoc xem nhti the hien hod tri 1, thi Ei431,04= 98/1 = 98; neu trao d6i 2 proton, hop chat thick xem nhtt the hien hod tri 2, thi = 98/2 = 49; con neu trao d6i ca 3 proton thi hop chat H3PO4thick coi la c6 hod tri 3 va phan kh6i luring tticing iing vdi 1 don vi hod tri (tlic &icing ltiong cila no) trong tracing hop nay la: EH3p04 = 98/3 = 32,7. Cdc nha hod hoc hien tai quan niem: hod tri cua mat nguyen to la so-lien ket hod hoc ma mot nguyen tet cua nguyen to do c6 the tao ra de ket cdc nguyen tU' khcic trong phan Cling \Mi khdi niem hod tri, ngvai ta ciing dung khdi niem s6 oxy hod cho cac ion hoac cho cac nguyen to trong hop chat. Tuy kh6ng coy nghia vat 1ST ra rani, nhat la trong cac phan tit phfic tap, nil-Ling so oxy hod khd tien dung cho nhieu mat thtic hanh hod hoc. Chinh vi khdi niem hod tri phdt triL va and rOng de gdn vdi ban chat nhieu loai lien ket, nen theo d6, khdi niem &icing Wong ding can chtoc cu the cho cac twang hop (each tinh diking Wong cua cac hop chat dvoc trinh bay trong chuong 8 y6 Dung dich). 41 Childng 2 CAU TAO NGUYEN 11- He THONG TUAN HOAN CAC NGUYEN TO HOA HOC MUC TIEU I. Phan tich du'dc not dung yet y nghia ceict he theec De Broglie yet he that bdt dinh Heisenberg. 2. Trinh bay thick ccic gici tri, y nghia va moi quan he cda 4 so ludng tie de mo to trang thcii cda electron trong Innu nguyen theo cd hoc luring tee. 3. Viet du'dc cau hinh electron, ye duck so' dd o luring tie ceia ccic nguyen tee, tie do suy docin du'o'c cau tao va tinh chat cua cdc nguyen to hoc. 4. Chi ra clu'dc nguyen nhan hinh thetnh ccic chu ky, nhom nguyen to sy' tuOn hoetn ve bdn kinh nguyen tee, the ion hoa, di lu'c electron NI di) am den ctict cdc nguyen toy. 1. CAU TAO NGUYEN TtY 1.1. Thanh phAn chinh cua nguyen tii Nha tri6t hoc Hy Lap Leucippe là ngttdi dau tien. Wang Wong ra sLt ton tai cua nguyen tit. Ong rang vao khoang nam 490 den nam 370 truoc cong nguyen. Ong giai thich rang khi chia nh6 mot vat thanh nhang phan nhO c16.n, cuoi ding dtioc nhang phan khong the chia nhO them dtioc nfia. Ong dat ten cho thong la atomos. Theo tieng Hy Lap, atomos c6 nghia la khong chia nhO dtioc. Chiang ta goi atomos la nguyen tit. Ong da ti cho rangneu c6 std khac biet ro ret giita tat ca nhiing gi ton tai trong vu try la bai vi moi vat, moi sinh vat dticic cau tao nen tii nhfing nguyen tit khac nhau lien ket lai. Mai toi. nam 1808, Oa tren cd s6 that nghiem, nha khoa hoc Anh, Dalton da neu ra gia thuye't nguyen tit goi la thuyet nguyen tit Dalton: nguyen tie la hat nhO nhdt cau tao nen ccic chat, khong the' chia nhO han nie-a bang cdc phu'dng pita]) hod hoc (xem mac 3, Chuang 1). Sau do, nh6 nhang thi nghiem khoa hoc, ngttdi ta phat hien ra rang nguyen tit khong phAi la hat vat chat cu6i ding ma no dttoc cau tao nen tit cac hat vat chat nhO hdn la electron, proton, ndtron (xem Bang 1.5, Charing 1), chling -CO nguyen tit c6 can tao phifc tap. 42 1.2. Mau nguyen tit tniac cd hoc 1udng tit 1.2.1. Mau nguyen tel Thomson Sau khi ngtfoi ta phat hien ra electron tich dien am là thanh phan cua nguyen tit, ngifoi dau tien neu ra mau nguyen tit là Thomson, ngitai. Anh, vao nam 1904. Mau nay cho rang dien tich diking &toe phan b6 deu trong than the tich cua nguyen tit va &foe trung hoa b6i cac electron ket chat trong "be dien diking" ay. LA mau dau tien con sd sai va som &foe thay the bang mau hanh tinh nguyen tit Rutherford. 1.2.2. MCiu hanh tinh nguyen tie Rutherford Tit ket qua cila thi nghiem ban pha la kim loci bang dan a (411e), nam 1911, Rutherford neu ra mau hanh tinh nguyen tit. Mau nay coi nguyen tit Om met hat nhan tich dien diking tap trung hau het khei Wong caa nguyen tit c1 trung tam va cac electron quay xung quanh hat nhan. Do sit quay caa cac electron xung quanh hat nhan gieing nhu cac hAnh tinh quay xung quanh mat troi trong he hA.nh tinh caa cluing ta, nen mau nay dit6c goi là mau hanh tinh nguyen tit Rutherford. Mau hanh tinh nguyen tit c6 gia triquan trong tren con dtiOng xay dung thuyet cau tao nguyen tit. Tuy nhien mau nay con mau thuan vii thvc to vg sit ton tai Wing ben caa nguyen tit hydro, vg quang ph6 vach c6 the quan sat &toe bang mat caa nguyen tit hydro ma Balmer da tim ra nam 1885. VI theo thuyet dien tit hoc c6 dien thi khi electron quay quanh hat nhan phai lien tuc phat ra nang Wong chi& dang song then tit. Do do clan toi hai he qua: - Ban kinh qug dao cda electron phai giam lien tuc, cal ding electron chap vao hat nhan. Nguyen 6.'1 diet vong. Trong khi do, nguyen tit van ton tai vfing ben. - Do ban kinh quy„dao ciia electron giam lien tuc nen Vic do goc tang lien tuc, tan s6 chuyen deng cua electron (se' vong quay trong 1 giay) tang lien tuc, bifc xa dien tit cua nguyen tit hydro phai Om day cac tia c6 blioc song giam lien.tuc, titc quang ph6 phat xa cua nguyen tit hydro phai la quang ph6 lien tuc. Trong khi do tirkic t6 quang pho phat xa cua nguyen tit hydro là quang ph6 vach. Nhung han the trong mau hanh tinh nguyen tit cua thay Rutherford scam duoc nguoi hoc tro cua Ong la. Niels Bohr, ngtioi Dan Mach giai quyet. 1.2.3. Witt nguyen tie Bohr (Niels Bohr) Xuat phat tit matt hanh tinh nguyen tit (nam 1911) va tit thuyet luring tit Planck (nam 1900), Bohr TA neu ra mau nguyen tit dit6c goi IA mau nguyen tit 43 Bohr. Mau nay gam hai tien de là co sa de' giai thich dtioc stl tan tai viing ben cua nguyen tit hydro va quang pile; vach phat xa cua nguyen tii hydro. Trude khi vao hai tien de cila mail Bohr to hay tim higu thuygt Wong tit Planck, mot trong hai digm xuat phat dm Bohr. * Thuygt luong tit Planck MOt vat ran bi clot nong se phat ra bite xa nhiet do dao Ong cua cac hat tich dien (electron, ion...). Pha thu duoc trong truang hop nay goi IA pha bite xa nhiet. Dg giai thich pha bite xa nhiet, nha vat 1ST Ditc, Max Planck nam 1900 da neu ra thuygt hicing tit &toe goi la thuygt Wong 61 Planck nhtt sau: Mat dao Ong tit dao dOng voi tan s6 v (nuy) chi c6 thg bite xa (phat ra) hay hap thu nang Wong voi tiing Wong nhO xac dinh goi là luong tit nang Wong E. Luting tit nang Wong E tST' le vdi tan sofv cua dao Ong tit E = by (2-1) O day h = hang s6 Planck = 6,626.10-2' erg.s = 6,626.10-34J.s Nang Wong cUa dao Ong tit phat ra hay hap thu a clang bitc xa dien tit. Anh sang cung IA bile xa dien tii duoc Maxwell chi ra vao nam 1865. Bai thg thuygt 'gong tit Planck sau do duoc Einstein phat trign thAnh thuygt photon anh sang. T6m lai theo thuygt Wong tii Planck thi anh sang not rieng hay blic xa dien tit not chung là tap hop nhfing luting tit nang Wong E = by. Tia y, tia Roentgen, tia tit ngoai, anh sang trong thay, tia hang ngoai, bite xa vi song, Vic xa song radio deu là cac bile xa dien tit. Chung chi khac nhau ve boric song ma th8i. &foe song cua tia y ca 10-2 A°, cila bite xa vi song ca 1 m, cila song radio ca 1000 m. Thuygt Wong tit Planck coy nghia rat quan trong. N6 phan anh &toe nang Wong (m8t clang ton tai ciia vat chat) c6 tinh chat gian do4n. * Tien de 1 cUa Bohr. Ban kinh qug ciao, t6c do chuygn &ling va nang luting cila -electron trong nguyen di hydro Dtia tren quan niem nang Wong gam nhang Wong tii xac dinh cua Planck, Bohr da dua ra gia thuygt rang electron trong nguyen tit hydro khong the c6 nhiing gia tri nang Wong bat lqr, ma chi c6 mot s6 gia tri xac dinh, tilt nang Wong cila electron là gian doan. Tit quan niem nay, Bohr neu ra tier' de 1 nhu Electron chuyen (1-Ong xung quanh hat nhan nguyen ti' hydro theo melt so quj) dao cho phep, khOng phcit va khong thu tieing Nhfing quji dao cho pile]) có ban kinh thoci man ctieu kien: momen ctong liedng quj,dao czia electron trong nguyen tee phai bang so-nguyen (n) Ian luvng ta' momen (--). 44 Phudng trinh cua tien de 1: h m . v . r = n. 2 . TC day m = khos-i Wong clia electron = 9,109.10-28g v = to-c dO chuye'n dOng cila electron, cm.s1 r = ban kinh guy dao'ciaa electron, cm n = nhfing s6 nguyen dozing, chi ro thai tu qug dao. so-Wong tai chinh. h = hang so- Planck = 6,626.10' erg.s = 6,626.10'4J. (2-2) Sau nay goi la h 2it kg.m".s-1 TE = sO pi = 3,1416 mvr = momen dOng Wong quy dao cila electron = 1,0544.10-27erg.s là Wong tai momen. s = 6,626.10' Trong phUong trinh (2-2) có hai dai Wong v, r chua xac dinh duoc hai dai Wong nay can xay dung them mot phuong trinh nfia sau day. Theo di8n dOng hoc co dien, khi electron chuy6n dOng tr8n qug dao tron mot cach b8n viing thi tong luc ly tam va luc hudng tam cUa electron phai bang 0. Trong nguyen -al hydro, hic ly tam cUa electron dtfoc xac dinh bang nang Wong chuye'n dOng cUa no va bang ban kinh r cua quy dao ma electron chuy8'n Ong tren do. No bang m. v2 . COn hic hang tam cUa electron ducic xac r dinh bang luc but tinh di8n•cila electron voi hat nhan. No bang _ 02 . Nhii vay r2 to có ph-Lb:mg trinh: m . v2 e2 (--T) r = 0 (2-3) r 0 day m = khOi Wong tinh cUa electron, g v = to-c dO chuy8n dOng cUa electron, cm.s-1 r = ban kinh quy dao clia electron, cm e = di8n tich cila electron =-- 4,80286.10' dvtd (don vi tinh Giai 118 phuong trinh (2-2) va (2-3) dude: h2 . n 2 (cm) 4 .7C 2. e 2m 2 it . e2 va (cm.s-1) h . n 45 Thay cac gia tri da bigt (h, it, e, m) vao (2-4) va (2-5) ditoc bigu thfic ban kinh guy dao cUa electron: r = 0,529. 10-8 . n2(cm) r-t' 0,53. 10-8. n2(cm) = 0,53 . n2(A°) r = 0,53 . x n2(A°) (2-6) va bigu thfic t6c do chuygn dOng cila electron: 1,90349 . 108 v = (cm.s-1) (2-7) n Trong (2-6) va (2-7), n la so luong tii chinh, có the có the gia tri 1, 2, 3, ..., co. - Theo (2-6) ta thay ngay ban kinh quy dao 67' le vdi binh phuong s6 this tu quy dao. Thanh this so vdi ban kinh quy dao this nhat (n = 1) thi ban kinh quST dao this hai (n = 2) gap 4 lan, ban kinh quy dao this 3 (n = 3) gap 9 Lan, ... Quy dao this nhat có ban kinh r = 0,53 A° duoc goi la ban kinh Bohr. Tri so 0,53 A° nay thtiang dtioc dung lam don vi dai trong cac bai toan v6 nguyen phan - Theo (2-7) ta thay a guy- dao cang xa hat nhan thi to'c dO chuygn dOng cua electron cang nhO. Thi du to'c dO dm electron d quy dao this nhat (n = 1) la 1,90349 x 108cm.s-1= 1903,490 km.s-1, con d quy dao this nam (n = 5) la 0,38069 x 108cm.s-1 = 380,690 km.s-1. - Nang Wong cila electron trong nguyen tii hydro: Nhu ta da big, theo thuygt dien Ong hoc c6 dik, the nang cua hai vat thg có Bien tich bang nhau (q) nhung nguoc dau (q va -q) dat cach nhau mot khoang r &foe xac dinh bang bigu thlic - q2 . Con dOng nang cua mot vat the co khoi Wong m, chuygn dOng vdi t6c dO v dtioc xac dinh bang bigu thlic m V2 2 Ap dung vao trtiang hop nguyen tit hydro, ta có: thg nang dm electron 2 là -e dOng nang cUa electron là m •v2 r 2 Nang Wong chung (toan phan) cila electron bang tong dOng nang va thg nang. Goi nang Wong chung cila electron d quy dao n là En, ta có: E. = m. V2 e 2 ) r (2-8) 2 Thay r va v tit (2-4) va (2-5) vao (2-8) dude he thiic nang Wong toan phAn dm electron a guy dao n la: E. = - 2 .7c2 .m.e4 h2 .n2 (2-9) 46 Thay it = 3,1416; m = 9,1096 . 10-28g; e = - 4,80286 . 10-10dvtd; h = 6,625. 10-27erg.s vao (2-9) chtoc: — 21,799788 10-12 En= . (erg) (2-10) n2 Do 1 erg = 0,624146. 1012eV nen (2-10) tra thanh: —13,6074 En= n2 (eV) lay trOn &toe: E. —13,60(eV) n2 (2-11) 6 day n la s6 this tit quy dao. 6 quy dao this nhat (n = 1), electron co nang along la -13,6 eV. D6 ding la trang thai cd ban, ben viing cua nguyen tit hydro. Sei di nang Wong c6 dau am la do quyti6c chon m6c the nang ciia electron a khoang cach vo ding Nen nguyen tit) bang 0. Voi n = 2 thi E = - 3,4 eV Voi n = 4 thi E = - 0,85 eV o cac quy dao cang xa hat nhan, nang Wong ciia electron cang lon, tien dan toi 0. * Tien d6 2 ciia Bohr. Quang ph6 phat xa nguyen tit hydro Nam 1885, Balmer da tim ra day quang ph6 phat xa nguyen tit hydro dau tien. N6 nam trong viing nhin thay, dttoc goi la day Balmer. Nam 1908, Paschen lai tim thay day nita, goi la day Paschen. Ca hai day cl6u là quang ph6 vach (Om nhi6u vach xep cach nhau). De m'au nguyen tit cua minh la cd sa giai thich dttoc quang phO vach nguyen tit hydro, Bohr da neu ra tien d6 2 duo% day. Khi electron chuyen to guy dao xa veto quy dao grin hat nhan ho'n se phdt ra lu'dng tit nang lacing E dudi clang bac xa dien tit. Ngu'dc lai,,neit electron nhdn du'dc lityng tic' nang luring E ely thi chuyen tit qujI dao gein ra quj",dao xa tito'ng zing. Luring tit nang Wong E bang hi6u so nang Wong ciia electron a quy dao xa (E.) va a quy ciao gan (Eg): E = E. — Eg (2-12) Theo thuye't Wong tit Planck, to c6: E = h.v nen: hv = E. — Eg (2-13) Thay bi6u thitc nang Wong (2-9) vao (2-13) dttoc: by = — 2,t2me4 — 2it2me4 h2 n2 h2 n2 (2-14) 47 Bien d6i (2-14) dtiOc: 2it2me4 ( 1 1 2 ) (S-1) n„ (2-15) h3 n2 n Ta con c6 cac h6 thfic (2-16), (2-17), (2-18) &led day: v = + (2-16) T = chu kST = thai gian can thi6t de dao d6ng tii thvc hi6n dtioc 1 dao d6ng, don vi la s"'. T x C (2-17) day X (lamda) = btic3c song (d6 dai song) = doan clang lan truy6n trong 1 chu kST, don vi la cm. C = t6c do anh sang trong than khong = 2,998.1010 x 1 (2-18) v (nuy ngang) = s6 song = nghich dao btioc song, don vi la cm"' Dtia vao (2-16), (2-17), (2-18) bie-n d6i (2-15) &toe: 2n2me41 1 h3C (nn) (cm-1) (2-19) g „ D4t RH = 27c2me4 h C (2-20) 3 Thay cac gia tri da bie't vao (2-20) thi: RH = 109761,039 cm"' lam troll s6 duck: RH 109761 cm-1 (2-21) (2-20) la bigu thfic hang s6 Rydberg d6i voi nguyen -al hydro, (2-21) la tri so hang so Rydberg do'i vdi nguyen tit hydro. Way (2-19) dtioc vie't nhif sau, khi thay tri so-RHvao: 1 1 v = 109761 . (-2-– (cm-1) (2-22) ng n, (2-22) &doe dung de tinh s6 song ciia vach quang ph6 nguyen tii iing voi hai guy-dao bat kST ngva nx. 48 Van dung tien de 2 ciia Bohr de giai thich cac day quang ph6 nguyen tit hydro. Quang ph6 vach nguyen tit hydro thu diiqc khi kich thich cac nguyen tit hydro bang clot nong, phong dien qua, ... cac electron se chuyen tit trang thai cci ban (n =1) len cac quy dao c6 n = 2, 3, 4, 5, ... c6 nang Wong lon hdn, Inc nay nguyen tit bi kich thich. 6 trang thai kich thich, nguyen tit khong ban, c6 dqi song trung binh ed 10-8s. Nghia la cac electron tit mite kich thich chuyen v6 cac quy dao gdn hat nhan hon, phat ra bite xa dien tit, tao ra quang ph6 vach phat xa nguyen tit hydro. Tdi nay ngttai to da thu elude cac day sau day: * Day Balmer (Balmer tim ra nam 1885): Mau do lam tim Vach 1,„ L„ LY X, 6559,70A° 4338,43A° Hinh 2.1. Day Balmer cua quang ph6 phat xa nguyen tit hydro Day Balmer g6m cac vach Tung voi stt chuyen electron tit cac quy dao c6 n 3 ve ding quy dao n = 2. S6 song ciia cac bite xa thuec day nay tinh theo tong thitc: = 109761 (-1 – (cm-1) 22 n2, v6i nx= 3, 4, 5, ..., co Vach La(electron tit n = 3 vd n = 2) c6: v = 10976 2 -2) 15244,5833 cm-1 (co X, = 6559,70 x 10-8cm = 6559,70 A°) Vach 1...17(tit n = 5 vd n = 2) co: v = 109761 (— 1 22 _ 1 52 = 23049,81 cm-1 (co = 4338,43 x 10-8cm = 4338,43 A°) Cac bite xa nay nhin thay dtt6c do mien nhin thay ciia mat ngtidi binh thltang c6 hitt& song tit 3900 A° toi 7700 A°. 49 - - - * Day Paschen (Paschen tim ra nam 1908): Nhung bite xa tao ra day nay nam trong mien hang ngoai, ling vdi ski chuyen electron tit cac quy dao xa ve ding guy d46 n = 3. SO song cila cluing tinh theo cong thitc: v = 109761 (3 n2 1 ) (em-1) X vdi nx= 4, 5, 6, ..., cc * Day Lyman (Lyman tim ra nam 1916): Nhiing bite xa tao ra day nay nam trong mien tit ngoai, ling vdi ski chuyen electron tit cac quy ciao xa vao ding quy dao n = 1. S6 song cila cluing tinh theo cong thitc: 1 v = 109761 (— – (cm-1) 11 2 n2x vdi nx= 2, 3, 4, ..., co Khi nx= 00 iing vdi ski chuyen electron tit guy dao xa nhgt vao quy dao n = 1, bile xa electron nay c6 s6 song la 109761 em 1, c6 nang Wong la E = E. - E1 =hxcx v = 21,80045 x 10 12erg = 13,60 eV. Gia tri 13,60 eV chinh la nang Wong lien ket eila electron i3 trang thai cd ban. trang thai cd ban ma electron nh4n elude 13,60 eV se tach kh6i nguyen tit hydro. Do do 13,60 eV la nang Wong ion hod this 1 cila nguyen tit hydro. * Day Brackett (Brackett tim ra nam 1922): Nhung bite xa tao ra day nay nam trong mien hang ngoai xa, iing vdi ski chuyen electron tit cac quy dao xa vao ding quy dao n = 4. S6 song cua cluing tinh theo cong thitc: v = 109761 1 1 (cm-1) n2x vdi nx= 5, 6, 7, ..., 00 * Day Pfund (Pfund tim ra nam 1924): Nhiing bile xa tao ra day nay nam trong mien hang ngoai xa, itng vdi ski chuyen electron tit cac guy-dao xa vao cong quy dao n = 5. S6 song cua cluing tinh theo cong thitc: v = 109761 1– 1 \ 2 nx (cm-1) vdi nx= 6, 7, 8, ..., CO Ngliai to con goi guy dao this 1, 2, 3, 4, 5... la quy dao L, M, N, 0, P... va goi day quang pile; theo ten quy ciao ma cac electron ding chuyen ve qug dao 50 ay de tao ra day. Do d6 cac day Lyman, Balmer, Paschen, Brackett, Pfund con dtioc goi tiling itng la day L, M, N, 0, P. MA.0 Bohr tiep tuc phat trieln. Nam 1916, Sommerfeld cho rang ngoai cac quy dao trOn cila Bohr, trong nguyen tit hydro con co cac qui ciao elip. se; Wong tii chInh n c6 gia tri bao nhieu thi c6 bay nhieu qui dao (trong d6 c6 1 qui dao troll con lai la elip). Cac qui dao nay c6 ding tri. seinang Wong En. De d4c truing cho cac qui dao khac nhau, nhting c6 cling so Wong tit chInh n, ngtiai ta be; sung them s6 Wong tit C goi la s6 Wong tit phu, C co cac gia tri 0, 1, 2, ..., (n - 1). Thl du: n = 3 c6 3 qui dao electron, c6 cac gia tri C la 0, 1, 2. Ca 3 qui dao c6 ding gia tri nang Wong la E3 —13,6 eV. 9 Do xuat hien s6 Wong tit phu t nen s6 Wong tit chInh n trout day cho biet qui dao this may thi nay cho biet lop qui dao this may. Tiep theo, nguai ta thay ling voi mot gia tri xac dinh so luring tit phu t, c6 the c6 (2C + 1) phuong trong khong gian cua cac qui dao electron. De dac truing cho cac phtiong khac nhau ngliai ta b8 sung s6 Wong tit m goi la so Wong tii tit. m c6 cac gia tri 0, ±1, ±C. Thl du t = 2 thi m = - 2, - 1, 0, +1, +2. Do xuat hien s6 Wong tit tit m nen s6 Wong tit phu t cho biet phan lop qui dao. Khi C = 0, 1, 2; 3, 4 ngthi ta goi la phan lop qui ciao s, p, d, f hiring ling. Cu6i ding, nam 1925, hai nha vat 11 Ha Lan Uhlenbeck va Goudsmidt da 136 sung s6 Wong tit s goi la s6 Wong tit spin. S6 Wong tit spin dac truing chb chuyen Ong rieng (tu quay) dia electron. S6 Wong tit spin chi c6 hai gia tri la + 2 —1 va 2 . Chung cling khac nhau 1 don vi nhu cac s6 luting tit n, C, BO 4 s6 Wong tit nhu the la dieu kien can va du de xac dinh day di sii chuyen &Ong clia electron. Do electron c6 4 d8 tit do, 3 dO roi ch8 trong kh6ng gian ling vdi 3 truc toa do va 1 d8 niia la sit ttt quay clia no. M8i to hop xac dinh 4 so Wong tii n, C, mu, ms dac truing cho mot qui dao xac dinh dm electron trong nguyen tit hydro. Mau Bohr nhu vay con goi la mdu Bohr - Sommerfeld. Nha van dung thuyet Wong tit nang Wong, mdu Bohr da giai thIch dtioc thiic t6 quang pho phat xa nguyen tit Hydro va xi* vai ion c6 1 electron giong Hydro. Tuy nhien, mail Bohr con nhieu sai 16,m nen no khong giai thIch cltioc quang ph8 cua cac nguyen to khac, tham chi la ci6i vdi Heli Co call tao chi phifc tap hon Hydro mot chtit. D'au vay, trong bite tranh ve nguyen 61, md.0 Bohr da clung gop to 16n, nhit chung ta se khOng thay trong mo hinh hien dai, la ton tai clict cac mac nang lu'dng rieng biet. 1.3. Mau nguyen tit theo cc] hoc Hiring tit Co hoc Wong tit la gi? 51 Vat 11 hoc da phat hien duoc hai clang cita vat chat la hat va song (con goi la dang chat va dang tniang). Trong Lich sit phat trien cua minh, mot thai gian dai, Vat li hoc co dien quan niem hai clang hat va song tach rai nhau, d6i lap nhau. Chang han hat c6 the sinh ra va cham nlittng khong dan den hien ttiOng nhi6u xa va giao thoa dac trttng cho song. COn song c6 the sinh ra hien tuong nhi6u xa va giao thoa nhung khong the sinh ra .hien Wong va cham dac trUng cho hat. Sau d6, Cd hoc Wong tii quan niem hai dang hat va song la thong nhat trong moi chuy6n &Ong cua moi hat vat chat (vi mo cang nhu vi mo). Nha c6 quan niem moi ve ban chat hong tinh song - hat caa vat chat ma Cd hoc Wong tii vita giai thich duoc tinh chat hat vifa giai thich duoc tinh chat song trong chuyen &Ong cua moi hat. Do giai thich duoc tinh chat song nen Co hoc Wong tit con duoc goi là Co hoc song. Co hoc Wong tit ra dai vao nhang thap ky ddu cua the V XX. N6 dua tren hai cd sa: + Cd hoc va dien Ong hoc co di6n. + Co sa toan hoc g6m dai s6 cac toan tii tuyen tinh trong kh6ng gian Hilbert va bieu di6n nhom. Cd hoc Wong tit la mon vat 11.1S7 thuy6t. N6 g6m mot s6 tien de co sa. Tit nhiing tien de nay, bang con &tang suy dien toan hoc ma nguai to thu dttOc cac ke't luan. Cac ke't luan ay &toe kiem cluing qua thuc tien. Dttdi ddy la mot s6 tien de cila co hoc Wong tii trinh bay cJ dang don gian, de hidu. 1.3.1. Song vat chat De Broglie Ban chat Wang tinh song - hat cita vat chat dttoc khang dinh ddu tien doi v6i anh sang. Di toi khang dinh nay la mot qua trinh tranh luan lau dai Oita cac nha khoa hoc. • Nam 1690, nha vat 11 Ha Lan, Huygens da ding be:co:51-1gtrinh "Khao luan v6 anh sang". D6 la thuy6t ddu tien v6 anh sang. Trong thuy6t nay, Ong cho rang anh sang c6 ban chat song. Anh sang la xung dan h6i lan truy6n trong moi truang dac biet goi la "ete". Ete lap ddy toanbO khong gian va than). duoc vao cac chat. Nhu vay song anh sang trong ete duoc hinh dung flint song am trong khong khi. Vai nam sau d6, nha vat 11 vi dai Anh, Newton lai data ra thuyel hat v6 anh sang. Trong thuy6t nay, Ong coi anh sang g6m nfrang hat vat chat phat ra tit ngu6n sang, chuyen dOng thang trong moi trttang d6rig nhat va tuan theo cac dinh luat ciia co hoc c6 di6n. Ca mot thai gian dai, hai thuy6t doi lap nhau v6 anh sang van ton tai. Ddu th6 ki XIX, nha vat li Phap, Fresnel dVa vao thuy6t song anh sang ciia Huygens giai thich thanh ding hien Wong giao thoa cua anh sang (do Young phat hien nam 1802) va hien Wong nhieu xa cua anh sang. Nam 1865, nha vat 11 Scotlen, Maxwell da chling minh rang cac tritang dien tii bien thien lan truy6n trong khong gian voi van t6c cua anh sang. Nhu 52 vay anh sang la song dien tit lan truygn trong khong gian. Thuye't song anh sang dticic ding c6 vting yang them. Nhting thuye't song anh sang khong giai thich duoc hieu ling quang dien caa anh sang (do nha vat 11 Dile, Hess phat hien ra nam 1887). Nam 1900, Planck neu ra anh sang g6m nhi-ing Wong tit nang Wong E, ma E = h . v. Nam 1903, nha vat 11 My g6c Disc, Einstein da neu ra dinh lust ve sv lien quan vdi nhau giita kh6i Wong va nang Wong cila met vat the bat ki. Dinh lust nay duoc bieu din bang phuong trinh: E = m . C2 (2-23) 6 day E = nang Wong clia vat the m = khoi Wong chuyen Ong caa vat the (khoi Wong Wong del tinh) C = t6c de cila anti sang trong chan khong Phuong trinh (2-23) et-mg cho thay sit lien quan vdi nhau gifia nhi-ing thay d6i ve nang hiong AE va ve kh6i Wong Am trong qua trinh bat ki. Do do (2-23) con duoc viet duoi AE = Am . C2 (2-24) Pinking trinh (2-23) va (2-24) con goi la he thlic Wong d6i Einstein. , Quan he gifia bli6c song va khoi Wong cila hat photon (hat anh sang) c6 the duoc xac Binh de clang tit tong thlic Planck (2-1) va tong thfic Einstein (2-23). Theo (2-1) ta c6: E =h.v = h —c Ket hop vdi (2-23) ta c6: m . C2= h Suy ra m .0 (2-25) a day = buoc song anh sang h = hang s6 Planck m = kh6i Wong Wong d6i tinh cua anh sang C = t6c do lan truy6n cua anh sang trong chan khong Nhtt vay anh sang vita the hien duoc ban chat song qua bileic song 2 vita the hien duoc ban chat hat qua khoi luong m. Nam 1903, vdi thuyet Wong del cua minh, Einstein da chling minh rang khoi Wong Wong del tinh m cua vat the vuot khoi Wong tinh mocila no tuan theo phuong trinh: 53 m mo 1 (2-26) V2 C2 6 day m = kh6i Wong -Wong d6i tinh cfra vat the mo= kh6i luong tinh cua vat the V = to-c dc) chuyen dung dm vat the C = Vic die) anh sang trong than khong Theo (2-26) ta thay mocUa photon = 0. Dieu nay c6 nghia khong c6 anh sang tinh (dung im). Tren cd sad tinh chat hat cira anh sang, nam 1905, Einstein da giai thich thanh tong hieu ling quang dien cfra anh sang. Ve sau, cling dua tren tinh chat hat nay nguai ta giai thich duoc hieu ling Compton cira anh sang (do nha vat li My, Compton phat hien ra nam 1923): Tinh chat hat ciia anh sang con the hien CI ch8 anh sang cling gay ra dp suat. NhU vay anh sang vita c6 ban chat hat visa c6 ban chat song. Hai ban chat nay la thong nhat, la chuyen hod qua lai. Nam 1923, nha vat li Phap, Louis de Broglie (1892 - 1987) da and rung quan niem ban chat hang tinh song - hat dia anh sang cho moi hat vat chat khac. Ong da data ra thuyet song vat chat va he thfic co ban dm no, lam nen m6ng cho su ra dai cira co hoc Wong tit. NOi dung dia thuyet nay: sit chuyin ring eUct moi vat the' có khoi lu'o'n,g tu'o'ng dui tinh m va tot c1.6 V deu lien /zest vdi mot song cc-) bu'de song chive xcie Binh theo he thae: X mV (2-27) 0 day h = hang s6 Planck Voi nhfing hat vi mo khi V << C thi theo (2-26) c6 m = mo. Thi du mot vien dan 100g bay vai to-c do 6 km.s-1duoc coi m = mo. Theo (2-27), vien dan c6 song lien ket voi but6c song: 6,626 . 10-27erg.s 100 g . 600000 cm.s' = 1,104.10-34cm Do buoc song qua nha nen tinh chat song trong tri.thng hop nay khong co nghia, khong quan sat duoc, not khac di la khong the hien tinh chat song. Vdi nhfing hat vi mo nhU electron chan.g han, c6 kh6i luong 9,109. 10.28 g, chuyen dung vai to-c d0 2200 km.s-1se co song lien ket vesi bu6c song: 54 6,626 .10-27ergs = = 3,306.10-8 cm = 3,306 A° (9,109 x 10- 28g) . (220000000 cm.s-1 ) Do Jou& song lon nen electron thg hign duoc tinh chat song trong chuygn d6ng. Nam 1927, dg kigm chiing tinh chat song dia sit chuygn dOng cila hat electron, Davisson va Germen da cho mot chum electron phat ra tit am cuc (tia am clIc) qua tinh the Nickel va quan sat thay c6 hi8n Wong nhigu xa electron ttiong to nhtt hi8n Wong nhigu xa gay ra bai anh sang. Kgt qua thuc nghigm cho phep tinh dttoc buoc song X, kgt qua phii hop IRK 1ST thuygt (2-27). , Mitt vay thi nghigm Davisson va Germer da chfing minh tinh dung dan cua song vat chat De Broglie. Ngay nay tinh chat song cila electron da dtioc ling dung Ong rai, thi du trong kinh hign vi electron. Theo h8 fir& De Broglie (2-27), tien d8 1 ciia Bohr trot thanh tat nhien. TInfc vay, electron chuy'en d6ng tren guy dao Bohr chi kh6ng phat ra nang Wong khi tao thanh song dUng, nghia la chu vi guy dao phai la s6 nguyen lAn buck song: 2icr = Thay X bang (2-27), ta c6: 2nr = n h = mVr = n—h mV 2,t Ta lad thay digu ki8n lucing tit ciia Bohr theo (2-2). 1.3.2. Nguyen Ur bat dinh Heisenberg Trong thg gioi vi mo, mot hat chuygn do, ng Ian duOc dinh vi trong moi trUang hop; nguoc lai, mot song duoc trai r6ng khAp kh6ng gian. Ngu mot electron c6 ca tinh chat hat- va song thi lam the nao chUng ta c6 th4 xac dinh chicle vi tri dia no trong nguyen tit? Nam 1927, nha vat 1.ST ngttai Disc Werner Heisenberg cid tim ra nguy8n 1ST bat dinh tren co sa cac ma tram toa d6 va ma tran van t6c khAng dinh rang: khong the' xac dinh chinh xac &rig theft ca vi tri vet vein tek cact mot hat. Nguyen 1ST bat dinh bigu thi cludi clang toan hoc cho mot hat chuygn d6ng theo phuong x nhu sau: h Ax.mAvx h Ax.Av .>_. (7-28) 47-c X 4Tum 6 day, Ax - d6 bat dinh ve vi tri; AVx - d() bat dinh ve van t6c; m - kho'i Wong hat; h - hAng s6 Planck; va It = 3,1416. Co th4 vigt cac h8 thlic tticing tit (7-28) cho cac toa d6 y va. z. 55 Theo he thiic nay ta thay do toa dQ (vi tri) ciia hat cang chinh xac bao nhieu thi do van t6c cua no cang kern chi/1h xac bay nhieu, va ngtioc lai. Tuy nhien, doi vdi hat có kheci hfOng lon (hat bui, hon bi, qua bong...) thi do bat dinh Ax va AVxvo cling nhO, co the bO qua. Vi du: qua bong khol Wong 0,200 kg chuyen Ong WA t6c do 50 ± 1% m/s. Vay xac dinh vi tri cUa no có chinh xac khong? Giai Theo (7-28), vdi AV„ = 50 m/s . 0,01 = 0,50 m/s, thi: 6,626.10-3' kg.m 2/s Ax > 5,27 . 10' m (4 .3,1416). 0,200 kg . 0,50 m/s Vay, d6i vdi qua bong ta có the do van t6c va vi tri vdi mile 4 chinh xac tuy y. Trai lai, tim vi tri va van t6c cua mot electron, tit do xac dinh &tang di cila no lai la mot van de hoan toan khac. Vi du: mot electron chuyen Ong gdn hat nhan có van tgc 6.106± 1% m/s. Xac dinh do bat dinh ve vi tri cua no? Giai DQ bat dinh ye van tgc: AVx= 6.106m/s x 0,01 = 6.104m/s. Theo (7-28), thu duck: 6,626.10'4kg.m2 /s Ax > 10-9m (4 . 3,1416) . (9,1096.10-3' kg) . (6.104m/s) Vay, dQ bat dinh ve vi tri dm electron lon hon khoang 10 Fan so vdi duang kinh toan bQ nguyen tit (10-1°m). Dieu nay có nghia la cluing ta khong the bigt chinh xac vi tri cua electron trong nguyen tii. Noi cach khac, chuyen cking ceict electron trong nguyen tet khong có quj,ciao (orbit). Dieu do hoan toan phii hop vdi ban chat song da the hien ro rang a electron. He thiic bat dinh (7-28) la mot trong nhang he thiic co ban nhat cUa cd hoc Wong tit, la he qua quan trong nhat cua Iy thuygt De Broglie ve tInh chat song cUa hat vi mo. He thiic nay diia ra tieu chu'an de danh gia cac d4c trying cila hat vi mo: bigt dO bat dinh AVxta tinh dtioc dO bat dinh vg toa dO Ax, theo do bigt diioc yang khong gian ma trong do hat c6 the CO mat. Ngtioc lai, bigt Ax, ngitai ta suy ra dQ bat dinh ve van t6c AV,, tit do có the xac dinh gAn citing ca van t6c, nang Wong, diing hiong va khgi Wong dm hat vi mo. Nhd tinh thong ke vay, cot hoc Wong tit tinh duoc xac sugt mot dai Wong vat 1S7 nhan mot tri so nao do. Chti ST rang, hang so" Planck (h) trong he thiic bat dinh có mot y nghia co ban, no phan ranh gioi gifia the gioi vi mo va the gioi vi mo, giiia vat ly co dien va vat ly Wong tii. Khi có the xem h = 0, 11w do cac quy luat cUa co hoc Wong 56 ▪ ▪ tii trung vdi cac quy lust cua cd hoc co dien. Con cac hien Wong khong the be qua tri so ciia hang se h thi clang khong tuan theo nirCing quy lust efia vat 1S7 co then nua. 1.3.3. Phu'o'ng trinh Schrodinger Thuyet song vat chat L. de Broglie va nguyen 1S7 bat dinh Heisenberg la nhiing khai niem ma dau cho cd hoc Wong tit. Nam 1926, Erwin Schrodinger (nha vat 1S7nguei Ao, 1887 - 1961) eta tim ra pinking trinh cd ban me to eau true liking tit cUa he vi mo. Trong ce hoc lueng tit, cac dinh lust v6 st/ chuyen deng cua cac hat vi mo dttec mo to bang pinking trinh Schrodinger, giovng nllif trong cd hoc co dien, sit chuyen deng cUa cac hat vi mo &tee mo to bang cac dinh lust Newton. Clang nhu cac dinh 1114 Newton, phiking trinh Schrodinger khong the suy ra dtkic tit nhang gia dinh tang quat hen ncia ma no &tee rut ra tit sit Wong tu gifia cac phtieng trinh cua cd hoc va quang hoc. Pinking trinh Schrodinger &tee thita nhan la met tien de, met nguyen1S7cUalS7thuyet mei. Trong nhang bai toan gap trong thuy6t nguyen tit - phan tit, tracing hop doi vdi met hat a nhung trang thcii ditng (nang Wong toan phan khong thay doi theo thih gian), phudng trinh Schrodinger c6 the dude vie-t nhu sau: h2 a2,1 , a 2 v, ( thlf = Ey (2-29) 87c2m axe a y2 a 6 day h = hang s6 Planck z2 m = khoi Wong cila hat U = the nang cila hat E = nang lacing toan phAn cila hat x, y, z =-cac toa d5 w = ham song (doe là psi hay si) a2 a2 a2 D4t: V2= axe (2-30) ay2az2 V2: toan tit Laplace (doe la nabla binh pinking) h2 Bat: = 8, V2+U (2-31) H : toan tit Hamilton (doe la hat mu), toan tit nang llang Thay toan di Laplace va Hamilton \Tao (2-29) dliec pinking trinh Schrodinger rut gon: Hyr = Ey (2-32) 57 Phuong trinh Schrodinger la pluiong trinh vi phan (chiia dao ham rieng phan), cap 2 (dao ham cao nhat la cap 2), thuan (ve' phai cua pinking trinh bang 0 sau khi da chuygn moi so hang chita bign s6 w va nhcing dao ham ciia sang trai) va tuye'n tinh (cac dao ham theo m6i Men so ddu ding ix* bac). Loai phtiong trinh nay co vo so-nghi8m. Neu yrl, W2, Wn la nhfing nghi8m d6c lap thi to hop tuygn tinh cua cluing ding la nghi8m cua phitong trinh. Dac tinh nay dan tdi mot nguyen 1ST goi la nguyen 1ST ch6ng chat trang thai: rigu mot he c6 th'87:1 nhung trang thai duoc mo to bang nhang ham song thi 118 dO cling c6 th8 a trang thai duoc mo to bang ham song W la to hop tuye'n tinh cac ham yr;: = ECiWi (2-33) Cila nhiing h8 so thuc hoac phitc tuST y. Pinking trinh Schrodinger la tong cu toan hoc &toe sit dung dd giai quygt cac bai than cu thd trong thuydt nguyen tit - phan tit theo cd hoc Wong tit. Vic giai quyet cac bai toan chinh la vi8c tim ra cac ham trang thcii tit va cac ruing luring E tuvng zing caa 1.3.4. Ham song yr — M6i trang thai cua mot hat hay mot h8 hat vi mo cluoc dac tiling bang mot ham xac Binh goi la ham song hay ham trang thai dO la nghi8m cua phuong trinh Schrodinger. Vdi nhang he d trang thai &Ling, ham trang thai w la mot ham caa toa d6 Descartes tv(x, y, z) hay toa d6 cau kv(r, 0, cp). Quan 118 gifta hai toa d nay la: x = r sin0 cow y = r sin() sing) z = r cos° Hinh 2.2. He cu'c cac toa dO Descartes va cgu 58 * )"( nghia vat 11 cUa ham trang thai y: He ham v mang mot y nghia vat 11, nem 1926, Max Born cho rang binh phttong modun cila ham song Itv12= tv.tv* (nen NJ la mot ham phitc thi y* la mot ham ph& lien hop cila w) ti le vol xac sue t tim thdy hat tai diem dang xet. Ltic nay 1w 2dV ti le vdi xdc suet tim thdy hat trong the tich dV tai toe do dang xet. Nen nhan ham y vdi mot h8 s6 N sao cho N2y2dV bang xac suet tim they hat trong the tich dV thi xac suet tim they hat trong toan 130 kh6ng gian se bang 1, do hic nay sit tim they hat tra thanh mot bign c6chac chan, co nghia: 11\12 tv2 dV = 1 (2-34) III (2-34) suy ra: N 1 (2-35) tv 2 dV Bieu thi c (2-34) la digu,ki8n chuan hod ham trang thai y. Ham y thoa man (2-35) goi la ham da chuan hod. 1-1"e' so N goi la 118 so chudn hod. Ngoai ra ham y con phai la ham don tri, hUu han va lien tuc. 1.3.5. Yng dung phzio'ng trinh Schrodinger cho nguyen tie hydro Bai town vg electron trong nguyen tit hydro la bai than don gian nhat, citing thai cling la bai toan cd ban nhat cila co hoc luong tit. Nhang kgt qua thu duoc trong bai toan nay la co sa cua mot h8 thong 11 thuygt vg cgu tao nguyen tit theo cd hoc Wong tit. CO the not bai town nay la mo hinh cho cac bai town dgi vdi cdc h8 philc tap hon. Tuy la don gian nhat nhung van rat phlic tap vg toan hoc. Phuong trinh song Schrodinger, hy = EyJ , la trung tam cila sit mo ta nguy8n tit theo co hoc Wong tit. Phuong trinh nay dOi hOi khi ham y dttoc xit 1ST bai town tit H thi cho kgt qua la ham y nhan vdi mot hang so E (la nang Wong toan phan cua mot trang thdi rieng duoc mo ta bai w). Nhtt da neu tren, pinking trinh Schrodinger có nhigu nghiem cho mot 118 da bigt. Vi du dgi vdi nguyen tit hydro, có nhigu ham thoa man phuong trinh Schrodinger, moi ham Wong ling vdi mot gia tri nang Wong rieng (tri rieng) cUa nguyen tit hydro. M6i mot ham song rieng nay ciia nguyen tit hydro goi la mot orbital ma ta se de cap chi tigt hdn phia sau. Trade khi neu ra huong giai va mot so nghi8m cu the cila phuong trinh Schrodinger cho nguyen tit hydro, cluing ta xem xet each sit dung phuong trinh nay de mo ta mot h8 gia thigt rat don gian thuang goi la "hat trong hop". M6 hinh hat trong hOp dtta ra tinh hugng mot hat duoc nhgt trong mot hOp mot chigu có bo cao vo han. Day khong phai la mo hinh chinh xac cho nguyen tit hydro. Nghia la, nguyen tit hydro kh6ng gigng nhti hat trong 59 hOp. 1.47 do de xii lY hat trong hop la: 1/ no mo ta toan hoc ciia c0 hoc song; 2/ no chi ra nhiing dac trong cua cac ham song; 3/ no cho bie't sti ltiOng tii hoa nang Wong bAt nguem nhti the nao. Vi nhfing 15r do ay, cach xii VT hat trong hOp la minh boa gAn gui cho ski mo to theo cci hoc Miring tii doi vdi nguyen tii hydro. Xet mot hat có khoi IUgng m chuygn d6ng ft/ do ra phia tru'oc va phia sau doc theo mot truc (gia dinh la truc x) giCta cac gia tri x = Nang lucrng 0 va x = L (nghia la chung ta xet h6p mot U(X) = co U(X) = 0 U(X)= co chi6u co kich thi.t6c L met). Gia thigt thg nang U(x) cua hat bang 0 doc theo daring di, frit cac digm kat thiic x = 0 va x = L, tai do U(x) vo ding Ion. Thu'c ta, vi hang rao lut dgy Ion vo ding a cac digm kgt thCic dia h6p nen, hat bi buOc trong h6p voi bac Wong kh6ng thd vu'ot qua (Hinh 2.3). x = 0 x = L Hinh 2.3. Ma hinh hat trong h6p mot chi6u veil cac bac taring thg nang Ion vo ding Nhu' da bigt, phuong trinh Schrodinger chita toan tit nang lacing Trong tru'Ong hop nay, thg nang bang 0 trong pham vi h6p, nang long a day chi la d6ng nang cOa hat di h2 2 c huygn toi va lui doc theo truc x. Toan tit cho d6ng nang nay la ,trong do h = — , 2m dx` 2n d2 h la hang s6 Planck, m la kh6i lu'ong ciia hat, va la dao ham bac 2 theo x (dang ceia dx` toan tit nay bat ngu6n tit cach m6 6 song theo vat ljr c6 dign). Thay toan tit ay vao phuong trinh Schrodinger H y = Ey, ta co: h2d2 w - Ey (1) 2m dx2 a day y la ham cua x [(y(x))]. Sap xgp lai phuong trinh, du'oc: d2 y 2mE (2) dx2 h2 Muc dich cua ta la phai tim cac ham rieng Ni(x) thoa man phu'cing trinh. Chu y rang nghigm cua phuong trinh nay la nhCtng ham nhu' d2y/dx2= (hang s6) x yr, nghia la mot ham ma dao ham bac 2 cila no có ding dang vOi ham g6c ban Tau. Ham có tinh chat thg nay la ham sin. VI du, xet ham Asin(kx), khi A va k la hang s6. Lay dao ham bac 2 theo x, d2 (A. sinkx)_ A d r d sinkx d = A (k.coskx) = Ak dx 2 - dx dx j dx = Ak(-ksinkx) = - Ak 2 sinkx = - k 2 A sinkx d2(A. sinkx) = - k2Asinkx "dcoskx" dx v•ay to có: (3) dx2 60 Day la clang ham thoa man phu'ong trinh Schrodinger cho hat trong hQp. Khi so sanh Bang tang quit cua phu'ong trinh Schrodinger (2) voi (3) ta they: 2mE = (4) 2 h Sap xgp lai bigu thik (4) ta có bigu th(tc cua nang luting: h 2k 2 E - (5) 2m Bigu thtk nay có jr nghia gi? thong ta de' gia thigt don gran A va k la hang so. Vay cac hang so do 95 thg nhan nhitng gia tri nao? Chu 9 rang ngu A, k có bgt k9 gia tri nao thi bigu thUc (5) clan den vo han cac gia tri nang luting có thg có - nghia la có sit phan bo lien tuc cua cac mile nang ktong. Tuy nhien, digu nay kh6ng dung vi nhitng 19 do cludc thao luan dudi clay. Chung ta se thgy: chi có mat so gia tri nang lu'ong cho phep, nghia la he du'oc luting tit hoa (thut ra, co hoc song trudc clay có kha nang giai thich du'oc ban chat ciia sit luting tit hoe nang luting ma luc dau ngu'di ta kh6ng nghi tOi do tech rdi hat va song). Si! luting tit hoe xuAt hien khi m6 ta hat trong hop theo co hoc song nho nhitng digu kien Hen. Bai vi thong ta phai mo to sao cho he tit nhien coy nghia vat 19 (giang nhu khi mo to dung dich nu'Oc chaa mat acid gap bigu thitc toan [H3012 = 9,0 x 10-6M2, du'oc nghiem la [F130+] = 3,0 x 10-3M va [H301] = -3,0 x 10-3M, ta tU dang loai IDO nghiem thit hai, vi nong do am khong có nghia vat 19. 6 clay ta se ap dung digu kien ben kigu nay cho tinh huang dang xet). Digu kien Nen cho hat trong hop có nhiing dac digm sau: 1) Hat khong thg ngobi hOp - hat bi buQc trong hop. 2) Trong mot trang thai cho truck, tong xac suet tim thgy hat trong hop phai bang 1. 3) Ham song phai lien tuc (CO gia tri ii moi digm xet). Nhu cla they a tren, ham W = A.sin(kx) thoa man phudng trinh H W = Ey. Bay gid thong ta xac Binh hang s6 k, A dg phu'ong trinh nay thoa man cac digu kien Nen kg tren. Vi hat phai trong hop va vi ham song phai lien tuc, nen gia tri cua y(x) phai bang 0 tai moi bac tu'ong, nghia la y(0) = 0 va w(L) = 0. Lu'u jr la ham sin bang 0 a cac gia tri goc 0°; 180° (T); 360° (2n) va v.v... Vi vay ham A.sin(kx) = 0 khi x = 0. Yeu cat., ham song phai bang 0 tai ma) bac tudng có thg bigu thi nhu sau: y(L) = A.sin(kL) = 0, nghia la k chi có mot s6 gia tri han chg, cu thg la k = n:rE/L vdi n la nhitng so nguyen (1, 2, 3...), nghia la: Wax)= A.sin( rut x), va do do: kv (L)= A.sin(—L) = A.sin(n7c) = 0 Dd gen mot gia tri cho hang so A, ta can trfdn khai mot khai niem moi. Khi Ong dung co hoc song dg mo ta vat chat cac nha khoa hoc (la kat hop binh phudng dm ham song veil xac suet. Vdi m6 hinh hat trong hap dang xet thi binh phudng gia hi ham song a mot digm cho trudc [41(2,0 ] cho ta bit xac suet tim thgy hat tai diem do, va xac suit tim thgy hat ten mot doan truc x có chigu dai dx xung quanh digm x la kit(x) dx. Bai vi chi có 1 hat trong hQp nen 61 t6ng xac suit doc theo truc x tit x = 0 dgn x = L phi bAng 1, nghia la hat phidu'oc tim thgy trong hQp (di6u kign bien de' neu tren). T6ng tat ca cac gia tri xac suit riay theo chigu dai cOa hQp (tit 0 —> L) bgng t6ng xac suit tim thy hat trong hop là: JW(x)dx = 1. Thay ty(x) = A.sin[(nic/L)x], to có: L L fl1J x)X d ( JA2 sin2(—ITTEx)dx = 1 (6) 0 0 L J 2 nit ( x)dx = 1 A2 (7) Chu y la gia tri cua tich phan (7) cOng bhng L/2, nghia la: L/2 = 1/A2, va A = -\/2/L Vol cac gia tri coa k va A nhu'tren, ham song coa hat trong hQp du'oc vigt: Al 2 nit W(x)= L.sin( Lx) Thay k vao bigu thac nang lacing (5), du'dc: h2k2 h2 (nit/L)2 E = 2m 2m 2, 2 n n Thay h = h/2it , co: E = vcti n = 1, 2, 3, 4... 8mL2 Cach ph8n tich nay du'a dgn mot lost nghigm ceia phudng trinh Schrodinger, trong do m6i ham song kiting (mg vdi mot trong thai nang lu'dng neng: Bang 2.1. Mdt so ham song va nang lu'ong tong (mg coa hat trong hOp mot chi6u n Ham Nang lacing 1 2 .n. n si x y , = ii-2 L L , kv2 = ?sin(- 271 X) W3 , = 1I-n2si ( 23: -c h 2 E 1 = 8mL2 4h 2 h 2 E2 = = 3 W 4= Al 2 sin L 9h2 E 3 8mL2 16h2 2h2 E 4= = 4 • • • 62 L /\ 4L I I • 8mL2 M1,2 • i • Nhu' vay, viec ang dung di6u kien !Dien dan d6n mot loat cac mut Wang lu'ong du'Oc luting tut hoa. Nghia la, chi có mot s6 mac nang luting cho phep dal vdi hat bi buOc trong hop. Ket qua nay rat phi hop vdi thctc nghiem (chang han vdi phi phat xa cua nguyen tit hydro) va la tut nhien kh6ng cho phep cac m(tc nang luting lien tuc cho nhang he du'oc buOc CO dinh, nhu' vat ly c6 dien da titng chi ra. Chu y rang nang luting du'oc luting tit hoa vi di6u kien bien da gan cho n chi nhan nhiing gia tri nguyen. Vi vay, chung ta goi n la s6 luting tit cila he. Chung ta có the lap so d6 cac nghiem dia bai toan hat trong hop bang cach ye ham song tutting ang vdi moi trang thai nang luting. Mite nang luting, ham song, su' phan b6 xac suat du'oc trinh bay a Hinh 2.4 cho 3 mac dau tien. Chu y rang moi ham song tien tali 0 d ria h6p, nhu' yeu cau dat ra 6 di6u kien bien. Noi cach khac, song ditng dac tru'ng cho hat phai có mot s6 nguyen Ian nU'a !Dirac song tu'dng du'dng chinh xac vdi kich thu'dc cua hOp. Nhi.tng bu'dc song vdi chi6u dai bat kj/ se khOng ton tai vi kh6ng thoa man dieu kien vita neu. Cung Wan Hinh 2.4 cho thgy, scr phan b6 xac suat tim thay hat la khac nhau clang kg giita 3 mutt nang luting. Vali n = 1 (mac Wang luting thap nhat hay trang thai ca ban) hat hau nhu' du'oc tim thay a trung tam dia hOp. Ngu'oc lai, vdi n = 2 hat di xac suat tim thay bang 0 6 trung tam h6p. Diem 0 goi la diem nut. S6 diem nut tang ding vdi sit tang n. A A' 10 9 1- 6 1 L 5 4 3 2 1 0 0 0 (b) (a) Hinh 2.4. a) Ba mac Wang luting dau tien doi vdi hat trong hOp mot chi6u theo sit gia tang dia h2/(8mL2). b) Cac ham song dia 3 mac dau tien clu'oc ye cho moi ham cUa x vdi cac gia trI cut dai la cho moi tru'ang hop. c) Binh pthrong cac ham song dia 3 mut Tau tien &roc ve cho moi ham cua x vdi gia tri cut dai la 2/L cho moi truting hop. M6t diem rat quan trong nEta dia hat trong hOp la hat khong the cc') nang luting bang 0. Bali vi, n6u n = 1 thi mro= 0 6 moi diem trong hOp (vi sin0 = 0). Dieu nay ding có nghia la r w o = u , dan den k6t luan khong tim thay hat trong hOp, mau thdan vdi di6u kien bien (hat 63 bu6c phi trong Nip). Dac didm có nang lu'ong khac 0 d trang trial cd bAn la didm dac trung cho tat ca cac hat có Wang lu'ong du'oc luring tit hoa. Ngu hat trong h6p có gia tri nang luting bang 0 có nghia la hat clang yen (vi Ong nang b5ng 0). Digu nay vi pham nguyen ljt bat dinh Heisenberg, bdi vi chimg ta d6ng thdi bigt chit-1h xac van t6c (b5ng 0) va vi tri cila hat (clang yen). Nhu vay, tat c5 cac hat luting to phi có mot Wang luting . toi thidu, thu'ang goi la nang luting digm 0. KhOng gi6ng nhu hat trong h6p mot chi6u, electron dm nguyen tit hydro di chuydn trong kh6ng gian 3 chi6u va có the nang, bdi vi no bi hap an bdi hat nhan mang dien tich during d trung tam nguyen tit. Su khac nhau nay the hien trong deo ham bac 2 c5 3 chigu cua toa d6 Decartes va them s6 hang thg Wang dm electron vao phu'dng trinh Schrodinger. Ngu'oc lai mo hinh hat trong hQp mot chigu chi có mot s6 luting tit xuat hien to kat quA toan hoc, nguyen tit Hydro trong khOng gian 3 chi6u lam xuat hien 3 s6 luting tit - nhu'dudc thay d phan tigp sau. * litieeng giai phticing trinh Schrodinger Cd hoc luting tit van gilt mo hinh nguyen tit hydro g6m mot hat nhan (hat proton) tich dien e0e3 trung tam va mot electron tich dien - e0chuye'n &Ong xung quanh tam. Theo thuyOt dien dOng hoc c6 dien, the nang ciia electron la –e2 – e2 U = . Thay U = vao phuong trinh (2-29) ta dtioc plutong trinh r r Schrodinger cho bai toan v6 nguyen tit hydro d nhiing trang thai ditng: h2 32uf 32uf 32uf e2 + + 9' 2 ) (E )W 8 2m ax- ay az 872m 0 (2-36) Do the nang U chi phu thuiic bie-n so r (khoang each tit electron tOi tam nguyen tit) nen trUCing th6 cs day la trucking xuyen tam. De thuan tien cho viec tinh toan, ngliCii ta sit dung he toa dO cdu d6 xac dinh vi tri cUa electron trong nguyen tit hydro. Trong he toa dO cdu, toan tit Laplace c6 dang: 1 a a v2 - r7 X— —) + r2A (2-37) ar (r2 ar 1 aa 1 32 day A . (sine ) + 2x (2-38) sine ae ae sin 4.2 Thay (2-38) va (2-37) vao (2-36) dtioc: 1 a 2 aW 1 e2 2.- * — (r ) + T2 AW + Eirc2m (E + —)N.i = 0 (2-39) r ar ar h2 r Trong toa dO cdu, ham trang thai tp(r, 0, (p) c6 the dude vie't sang dang tich cila ham ban kinh R(r) chi phu thuOc vao bie'n so r va ham cdu Y(0, (p) chi phu thuOc vao cac toa dO g6c 0, (p: w(r, 0, (p) = R(r) x Y(0, (p) (2-40) 64 Thay (2-40) vao (2-39), re3t dung pinking phap phan li bien se' de tach phttong trinh (2-39) thanh hai pinking trinh don gian hat: + Phitang trinh ban kinh chi chita bie-n se'r va + Phttang trinh goc chi chita cac toa de goc 0, (p. Ti6n hanh giai phttang trinh ban kinh va philong trinh g6c &lac cac nghiem cua thong. Nghiem cua phtiong trinh ban kinh la cac ham ban kinh phu thuec vao hai so nguyen n va C, nen ta ki hieu chung la 11„c(r). Nghiem dia pinking trinh gee la cac ham c6u phu thuec vao hai so nguyen C va m, nen ta ki hieu chitng la Ycm(0, (p). Thong tut trong thuye't Bohr - Sommerfeld tritoc day, a day n goi la so Wong tit chinh, t goi la se Wong tit phu, m goi la s6 Long tit tit. Ch'ing cang nhan cac gia tri nhtt trong thuygt Bohr - Sommerfeld. Chi khac a chi!, cac so litong tit d day có ditoc la nha viec giai phitong trinh Schrodinger. Nhan nghiem cita phitong trinh ban kinh vii nghiem cua phtiong trinh gOc met cach Wang ling (tilt hai nghiem nay c6 ding gia tri so Wong tit C), ta dttOc nghiem cua phttang trinh Schrodinger (2-39) la cac ham trang thai yncm: WnCm = Rnc(r) • Ycm(0, (p) (2-41) Cac ham trang thai kvntn, dac truing cho cac trang thai cila electron trong nguyen tit hydro. Luc nay ngttai ta goi cac ham trang thai yntmla cac orbital nguyen tit (vie't tat la AO). Khi C. = 0, 1, 2, 3 ta ce cac orbital nguyen tit toting ling la s, p, d, f vie't tat Wong itng la AO-s, AO-p, AO-d, AO-f. Khi C = 4 fres len ta goi cac orbital Wong ling bang cac chit cal tigp theo sau chit f theo this tut cac chit trong bang chit cai, do la cac chit g, h, Bang 2.2 cho bie't moi quan he giiia 3 so luting tit trong su xac dinh met orbital nguyen thai ghi chit tom Cat ten, Sr nghia, cac gia tri (lilac phop cho mot so- Wong tit va kS7hieu cac AO. 65 Bang 2.2. Quan he giCra 3 s6 Ittong 1171 (SLT) xac dinh mot orbital nguyen tit (AO) n i SLT chinh (kich thttoc, tieing Wow) 1,2, 3, 4... ( SLT phy (hinh dung) () den (n-1) m SIT tic (dinh htrang) _e 0 -F.e Ten I“/ hi0 AO AO tynem T6ng sO AO (cho moi gia tri n) = ni 1 0 (s) 0 is Two 1 = 12 - 0 (s) 0 - --------- • 2s 111200 . -1 - --------- 2py T21-1 4 = 22 - 1 (p) '::, 0 2pz 'P2.10 --- +1 2px T21+1 .. 0 (s) 0 3s T300 .-- -1 3py T31-1 ..-- 1 (p) 0 3pz 11/310 --- +1 3px T31+1 ..... -2 3dx2-y2 T32-2 9 = 32 ..- -1 . --------- - 3dyz T32-1 '• 2 (d) .:'..:.. 0 3dz2 T320 --- +1 3dxz T32+1 ..- +2 3dxy 11'32+2 ..: 0 (s) 0 4s T400 -1 4py T41-I .... 1 (p) :: 0 4pz T4I0 .."'. +1 ------ - - 4px T41+1 .- -2 --------- - - 4dx2.-y2 T42-2 -1 4dyz 11f42-1 2 (d) •".. 0 4dz2 T420 16 = 42 --- +1 ... -. .+2 . --------- 4dxz 1P42+1 • - 4dxy T42+2 -3 4fx'-3/5x 11143-3 -2 4fxyz T43-2 .-- -1 4fx(Z-y2) T43-1 \ 3 (f) - 0 4fz3-3/5z T430 ' +1 4fz(x2-y) 1p43+1 ' +2 4fy(x2-0 T43+2 ... +3 4fy3-3/5y 11-143+3 66 Bang 2.3 ghi mot so nghi:Om caa phtiOng trinh song Schrodinger cho nguyen tti hydro. Bang 2.3. MQt s6 ham tang trai coa electron trong nguyen tit hydro (thanh phgn goo) lintm = RrIt•Ytm Ten orbital nguyen ter Ham ban kinh Rnt (thanh phgn ban kinh) Ham cau Ytn, W100 hay 1s 2.e' 1 1 - r 2jc e r W200 hay 2s 1 -- 2 1 L.(2 - r).e 2 ,_ .(2 - r).e 2A/2 2/71 4-arc W21-1 hay 2py 2 ( — ) ; 2V6 .r.e r 2,/ it r 4-l2i y - .e W210 hay 21pz nt AfJ- z 1 - -2' () z.e 2-jE - r 4 27c N121+1 hay 2Px nt -‘i , x , 1 2 .x.e ,- k. — ) 24 rt r 4-arc W300 hay 3s 23 r 1 1 -- r ,--.(27 -18r + 2r2 ).e 3 81 ,.(27 -18r + 2r2).e 2AFE 81-J3n 4,.(r2 -1i- - ( y r 2 ' 2 ,.(r 6).y.e 3 -- 3 ,- — ) y31-1 hay 3 py 81-J6 81 22n -6r).e 2v rc r khio hay 31pz nt , Z , 2 -- .(r 6).z.e 3 f- k — .? 2,./7c r 81-%/27t W31.1 hay 31ox nt -13-- x 2 .(r - 6).x.e 3 r-- ( — ) 2-0c r 2zt W32-2 hay 3d 2 _ 2 4 2 ; "if x2 y2) ( ) , .(X2 - y2 ).e 3 , r .e . 2 x y 81-00 4-Frc r- 81A2n kV32-1 hay 3dyz nt Ark) yz 2 -3 2-v2rc r2 y z e r--- ( ) 81-fiTc W320hay 3dz2 nt ,N5 z 2-r 2 ) 1 -- ,.(2z2 - x2- y2 ).e 3 (3 4/7- r2 81V6 n N132+1 hay 3dxz nt N) () xz 2 --r 2-57C r2 81 2n x.z.e 3 W32+2 hay 3dxy nt 15- xy r 2 --3- .x.y.e (-2-) 4-jc r 81-\h7c (.5 day don vi dai la ban kinh Bohr 0,53A° = ao e la co s6 logarit hi nhien = 2,7182. __ N.P.e " 67 • vay, co the vigt clang nghiem tang quest cua phtiong trinh Schrodinger cho nguyen tit hydro: yam= (2-42) N - thita so chuAn hoes (hang so) P - da thitc cua cac toa dO r - khoang each tit go'c toa dO (hat nhan nguyen tii) den diem dang xet n - mot se nguyen (s6 Wong tit chinh) 1, 2, 3... * nghia vat 1S7 ciia ham song Nhac lai rang, yr la mot ham toan hoc khong c6 tinh chat mieu ta vat nhung w2lai c6 tinh chat ay. Gies sit c6 2 vi tri trong khong gian, met vi tri dude xac dinh bOi toa dO r1, 01, cN va vi tri kia 136i toa dO r2, 02, (p2. Xac suat 'Wang dot tim they electron gdn vi tri 1 va 2 dttoc xac dinh bang each thay cac gia tri cua r, 0 va cp cua hai diem vao ham song, binh pinking gia tri cila ham song, va tinh tST so sau: [T(ri , 01 ,(pi f dVi N1 P-F(r2 , 02, (p2]2dV2 N2 Ts, se; N1/N2IA tST le xac suet tim they electron trong the tich vo cling nhO dV1va dV2gan diem 1 va 2. Vi du ne'u ty s6 N1/N2la 100, nghia là electron dude tim they trong dV1vdi xac suat 16n gap 100 Pan trong dV2. Truing hop xet dV1dV2thi tY' s6Ni/N2la tY) le xac suat tim they electron a vi tri 1 va 2, khi Ay electron duoc tim they & vi tri 1 vdi xac suat 16n gap 100 Mn vi tri 2. Diu Sr la mo hinh nay khong cho chUng ta thong tin ve viec khi nao thi electron a vi tri 1 hay 2 hoac no di chuyen giiia hai vi tri ay nhu the nao. Tinh trang and ho nay phit hop vdi nguyen 1ST bat dinh ciia Heisenberg. Binh pinking ham song chi bieu thi sit phan 136 xac suat. MO each khcii quest thi: W20 le vdi mat do xac suet, nghia la vie suet tim they electron tai mot dam trong khong gian; va 1,clV tj, le vdi xac suet tim they electron trong ye-u to the' tich dV. * Bieu dien ham song V6i mot mitt nang luong dela ra, cluing ta c6 the bieu din ham tv de' hieu bon nh6 hinh anh cita cac bieu do, do thi hoac mei hinh. Co 3 cach bieu din thuang dung. 11 Bieu dd va do thi mat dO electron a biL din xac suat tim they electron tai mot diem (y2) trong khong gian each hat nhan mot khoang r. Chung ta khong the xac dinh &toe electron a dau tai m61 thai diem, riffling co the xac dinh duoc no c6 khi nang tan tai a dau, nghia la phan lon thai gian no 68 c6 mat d dau. Neu c6 the thong ke lei tat ca cac vi tri cila electron tai moi thoi diem no chuyen Ong song xung quanh hat nhan, hinh anh thu dtioc c6 the cam nhan nhlu la dam may cac vi tri ciia electron. 21 May electron a bi4u din mien khong gian gen hat nhan nguyen tii dttoc gidi hen bang mot bg mat, trong do chiia 90% tang xac xugt tim thgy electron. Nghia la 90% thai gian electron c6 mat trong mien khong gian nay. Liu Y rang dam may electron la hinh anh kh8ng c6 thiic - khong c6 nghia la electron khuech tan khap dam may. May electron chinh la each bigu din kith thuoc Wong doi cUa orbital duce dinh nghia mot cach quy Lick, do'ng thai cho thgy hinh dang khac nhau cua cac orbital nguyen tit. 3/ Bie9u do va dd thi phoin bOs' xac suet xuyen tam (14 bigu din tang xac suet tim thgy electron d mot khoang cach r nao do tit hat nhan. De lam dtioc diet' nay, thong to chia phgn the tich ngoai hat nhan ra thanh nhieu phgn nh6, mOng, Bong tam, hinh cgu (giting nhtt cac lop ao cua cu hanh) va tim tong gia tri y2trong m6i vO * Bi'411 din cac orbital cita nguyen di hydro — Orbital Is (Wm). Hinh 2.5 cho thgy 3 each bieu din orbital nay. Khoang each A tif hat nhAn Khoang each C D tir hot nhan Hinh 2.5. Bigu din xac suet tim they electron trong nguyen tit H 8 trang thai co ban / orbital Is. A. Bidu d6 mat dO electron ten mat cat ngang nguyen tit H. M6i chern mieu to xac suet tim they electron tai mot diem ngoai hat nhan (ho5c mot thd tich vo tang nh6). B. 06 thi mat d6 electron (ye theo th6ng tin tit A) cho they mat do gi5m khi r tang nhitng kh6ng bao gid bAng 0. C. Chia thd tich nguyen to' thanh chu6i vó ca'1.1 (Tong tam (6 My la mat cat ngang) va (gi6 thigt) dem cac diem trong the tich nn8i vó cgu. D. D6 thi ph5n b6 xac suet xuyen tam (ye theo th6ng tin t0' C) cho they tong mat dO electron (tong t1J2) trong the tich m6i vó cgu. Vi mat d6 electron giam ch5m hcsn sit tang the tich ciia v6 cgu, d6 thi c6 dinh. E. May electron hay hinh clang orbital Is (theo dinh nghia de-data) la mot qua cgu c6 ban kinh 1,4A°. Ket qua trinh bay d Hinh 2.5A va B la bik din xac suet 6 natii digm doc theo mot dining lien tuc duoc ye bgt ky theo pinking nao tit hat nhan. Do dac 69 tinh cila ham khoo(xem bieu thlic cim ham trong bang 2.3) chi phu thutic r, xac suat tim thgy electron tai mot diem nao do (w2) se 16n nhgt d ga'n hat nhan va giam nhanh khi khoang cach tai hat nhan tang. Bai vi xac sugt khong bao gia bang 0 nen kith thtt6c cila orbital cang khong dttOc xac Binh. Vi kv2(ciing nghia vai mat dO electron) phan b6 d6i xung cdu quanh hat nhan (do chi phu tin* r) nen kith thii6c Wang dici clia orbital is cua nguyen tit H &toe dinh nghia la mot qua cdu chiia 90% tang xac sugt tim thgy electron. Nghia la 90% thai gian electron c6 mat trong qua cdu nay. Ap dung quy u6c vita neu va tinh, ta thu &lac qua cdu có ban kinh 2,6a., hay 1,4.10'm = 1,4A° = 140pm. D6 thi d Hinh 2.5D ye tang xac sugt tim thgy electron trong m6i v6 cdu (ghi tren truc tung) theo khoang cach r tit hat nhan (ghi tren truc hohnh). DO chinh la cach bieu din 47E1'2%200 dr theo r. 6 day dr la be day cila \TO cau. D6 thi có ctic dai do 2 anh htiCing d6i lap nhau. Xac sugt tim thgy electron a mot vi tri nao do se lon nhgt d gdn hat nhan, nhung the tich va cdu lai tang theo khoang cach tit hat nhan. Vi vay, khi di chuye'n ra xa hat nhan, xac sugt tim thgy electron a mot vi tri nao do se giam, nhting the tich cUa va cdu lai tang chiia dtioc nhie'u vi tri hdn. Suy ra, tong xac sugt tang theo ban kinh r va sau do giam vi xac sugt tim thgy electron a mtii di6'm tra nen rat nha. Ve mat toan hoc, se xay ra ctic dai vi ham 47u-2 4'20ocó r2tang theo r trong khi Witogiam theo r. Doi vai nguyen tit H, xac sugt xuyen tam cuc dai cUa orbital is xay ra khoang cach 5,29.10-11m hay 0,529A° tit hat nhan. Dieu dac biet la khoang cach nay dung bang ban kinh quy dao trong ding ma Bohr dua ra, vi \Tay goi la ban kinh Bohr, kS7 hieu a.. Orbital 2s, 3s (Hinh 2.6) deli co dang hinh cdu dAc thing cim orbital ls, nhttng lon hdn dang cdu is do gia tri n tang. Cac orbital 2s, 3s có 2 \Tung, 3 \Tung mat dO electron lon, co clic dai, d khoang cach xa tit hat nhan. Ghia cac \Tung bi ngan cach bet). nhfing nut hinh cdu, a do xac sugt phan b6 bang 0 (y2= 0 a nut, Wong tu nhtt Men dO cua mot song). S6 nut tang khi n tang. Doi voi orbital ns so nut bAng n-1. Orbital p dtioc trinh bay a Hinh 2.7 vai mot so cach bieu diAn. Vi gia tri cua cac orbital p vita phu thuOc vao toa x, y, z vita phu thuOc vao r (xem Bang 2.3) nen de? I wp I 2 16n thi hoac I x I , ho4c I y I hay I z I phai lon va r nha. Do do may electron cila chUng co hinh dang nhtt qua ta del (2 thug hinh cdu) trai doc cac truc x, hoac y, hoac z cua he toa dO Decartes. Gina hal thug dtioc ngan cach bai mot nut a hat nhan, có the them cac nut khac tuSr gia tri cua n. Cdn nho rang, cac orbital nguyen tit la nhang ham toan hoc, chUng co dgu (gi6ng nhu ham sin dao citing tit phAn diking sang phdn am). Cac ham ciia orbital ns luon &icing trong khong gian 3 chi6u, nghia la gia tri cila ham d bgt kST diem nao trong kh8ng gian de'u cho ke't qua la mot s6 dtidng. Nguac lai, cac ham orbital p có dgu khac nhau a cac vung khac nhau trong khong gian. 70 O a) ,>. E E 0,0 yip 1/43 F, Z. E X n=1 1=0 O a) E E Re) cro 0E x 03' n=2 1=0 C O a) >, •,(75 E E <10 zu ip E x 0 2 4 r (10-10m) n=1 1=0 E ‘ca x 7 Co X 6 8 10 - r (101 0m 12 14 E C X CO X 2 r (10-10m) c c LRO o. 0 2 4 r(1011) m) Al s orbital C0) 'Co C R0 2 4 6 r (10-10m) B 2s orbital 4 6 8 r (10-10m) C 3s orbital 10 12 14 Hinh 2.6. 06 thi mat dO electron (phia tren); mot phan may electron (giaa); va d6 thi phan b6 xac suat xuyen tam (phia du'oi) cua ba orbital s. A) Orbital ls B) Orbital 2s C) Orbital 3s (Don vi cua truc ngang la ban kinh Bohr = 0,529.10-10m) 71 C D • a Fr is B 5 8 A E Hinh 2.7. Bidu din cac orbital p A. Bidu din mat do electron caa orbital 21Dx B. D6 thi phan b6 xac sugt xuyen tam orbital 2p C. Hinh clang va so dinh hu'Ong cua cac may electron 2p D. Bidu din mat d6 electron 3p trOn mot mat cat ngang nguyen tii E. D6 thi ph5n b6 xac sual xuyen tam dia orbital 3p — Orbital d voi met so- cach bieu dien duoc trinh bay a Hinh 2.8. Ltiu 57 rang orbital d dau tien xuat hien chid gia tri so Wong tii n = 3. Nam orbital d có 2 hinh clang co ban khac nhau: dang 4 thug (dxy, dyz, dxy, ) va dang 2 thug kern theo met "that lung" (dz2). Dau cila orbital d duoc chi ra trong cac be mat gioi han. Chu ST la dgu + hay - ghi trong cac dang may electron chi coy nghia la gia tri cilia ham trang thai y hoac > 0 hoac < 0 ttfdng ling ma thoi. Dieu do có loi cho giai thich su hinh thanh lien ket hod hoc sau nay. 72 IN. I 0 Itr 1*2 3d I I BO 2 4 6 8 W 12 1' A C Hinh 2.8. Bidu dien cac orbital 3d A. Bigu din mat d6 electron B. 06 thi phan b6 xac suat xuyen tam C. Hinh dang va sir dinh hudng cOa cac may electron (Lilu ST: 4 thug cita orbital dxz, dyz va dxy d trung tam cac mat phang va nam giita cac true tilting ling. 4 thug cita orbital dx2 _y2a trung tam mat phang xy va nam doc theo cac truc x va y. Orbital dz2c6 2 thug doc theo truc z va mot vanh nam i3 trung tam mat phang xy). * Cac so lacing tit cUa cac electron trong cac nguyen tit Cac s6 Dieing tit dac triing cho ski chuyen Ong cita cac electron khong nhting trong nguyen tit hydro ma con trong cac nguyen tit khdc bat ki. Nhcing dac tritng nay rat quan trong de hieu biet nhfing tinh chat cita cac chat va ban chat cita lien ket hod hoc. Do d6 chting to de cap den ST nghia cua the so lacing tit chi tiet hon. a. So-lu'cing chinh n n c6 the co cac gid tri nguyen &tong 1, 2, ..., 00. n cho biet lop orbital, kith thy& may electron (orbital), nang Wong dia electron, s6 mat nut dm orbital. Neu trong thuyet Bohr - Sommerfeld, n cho biet lop qui dao thi theo cd hoc Wong tai n cho biet lop orbital. n bang bao nhieu thi lop orbital ay co orbital. Thi du n = 3, lop orbital nay c6 32= 9 orbital. Theo cd hoc lacing tit, electron trong nguyen tit c6 the thay d khoang cdch bat ki tOi hat nhan, nining xac suat tim thay of nhfing khoang each khdc nhau 73 la khac nhau. Khi bidt mat do phan b6 cUa electron, chting ta c6 thd tinh dtiOc khoang each trung binh (rtb) tit vi tri cila electron toi hat nhan. Khoang cach nay dac trUng cho kich ankle cila may electron. Lay tich phan ham ban kinh se thu thioc rtb. Gia tri rtbduoc xac dinh bang cac gia tri n va 1. Doi vdi electron trong nguyen tit hydro va nhfing ion giong hydro (nhfing ion c6 met electron, met hat nhan nhu He, Li', Be'), he thitc tinh rtbla: rtb = a } 'n2 . 1 { 1 + [1 1(1+1)1 (2-43) 2 n2 6 day at, = ban kinh qui dao Bohr this nhat (0,53A°) Z = dien tich hat nhan cUa hat. Tit (2-43) cluing ta thay rtbxap xi ti le vdi n2. Suy ra n xac dinh kich thuoc may electron, n tang, kich thuoc may tang. Thi du kich tint& may 3s > 2s > ls, kich thtfoc may 3p > 2p. Tit tren ta thay, trong nguyen Oa hydro, d6i vdi cac trang thai ls, 2p, 3d... tai cac khoang cach trizng vdi ban kinh quy dao Bohr Wong ling, xac suit tim thay electron là cue dai (xem Hinh 2.5, 2.6, 2.7, 2.8). Nang Wong cila electron trong nguyen tui hydro chi phu thuec vao gia tri s6 Wong tit chinh n. Giai phtiong trinh Schrodinger (2-39) duoc he thdc nang luong cUa electron trong nguyen tit hydro: — 27c2 me4 En= (2-44) h112 He -Or& nang Wong (2-44) trong co hoc Wong tit triing vdi he tit& nang Wong (2-9) trong thuydt Bohr. Khac thuydt Bohr a ch6 cc; hoc Wong tit thu thick ke't qua nay khong can dila vao nhiing gia thidt rang electron chi c6 the chuydn Ong trong nhiing qui dao xac dinh. Theo (2-44) ta thay khi n tang thi nang luting tang. Do n xac dinh nang Wong cila electron, mot dac truing chinh cila electron trong nguyen tit nen n duoc goi la s6 Wong tit chinh. S6 Wong tit n con cho bie't s6 loai mat nut ciia orbital. Thi du n = 2 c6 hai loai mat nut. 1\46i mat nut la qui tich nhting didm c6 y = 0. Do NJ = 0 nen y2= 0. Vi \Tay mat dO may electron 6 mat nut bang 0. Mat di dai vo han khOi hat nhan cling la mat nut do trong truang hop nay khoang each r = oo nen NJ cling bang 0. Su hien hau cUa cac mat nut trong ski phan b6 mat de electron nay sinh tit cac dinh luat dm the gioi vi mo. Syt chuyen dOng cua cac hat diioc mieu ta bang cac phuong trinh Wong tit nhu cac phuong trinh cua chuyen Ong song. Trong mei met song c6 nhfing diem a do Ellen de dao Ong bang 0. Ndu dao deng ba chieu thi tang nhang didm nay tao thanh mat nut. Cac mat nut cilia 74 cac orbital c6 hai mot loai khong di qua hat nhan, mot loai c6 di qua hat nhan. Loai this nhat la nhung mat cau, tam dia chung trung voi hat nhan. Loai this hai la cac mat phang hay mat non, cluing di qua hat nhan (xem Hinh 2.9). SU c6 mat dia mat nut cau duoc chi ra trong thanh phan ban kinh cua ham song - d khoang cach r xac dinh c6 yr =. 0. Didu nay d8' thay trong Hinh 2.6, 2.7. b. So-lu'o'ng tet phi! S6 luong tit phu t quy6t dinh gia tri dia /amen Ong Wong orbital ciia electron. Goi momen nay la M, cd hoc Wong tii da xac dinh dudc 118 thiic sau: M = Afe (i +1) —h (2-45) 27-c day M = momen dOng Wong orbital cila electron = 's6 Wong tit phu co cac gia tri 0, 1, (n-1). Thi dun = 3 thi t = 0, 1, 2. h = hang s6 Planck. Cac electron a ding lop hay khac lop orbital nhting c6 ding gia tri s6 Wong tit t thi c6 ding gia tri M. Thi du cac electron ns (d8u cot = 0 nhung n = 1, 2, 3, ...) thi de'u c6: M = V0(0+1) 2 t= 0 Cac electron np (d6u co t = 1 nhung n = 1, 2, 3...) thi d6u c6: h= h 2rc Ail (1 + 1) 27c Bdi cac electron c6 ding gia tri t thi co ding gia tri M nen s6 lacing tit t con duoc goi la s6 lacing tit orbital. t cho bigt dang hinh hoc cila may electron. Khi t = 0, may c6 clang hinh cau; t = 1, may co dang qua to &Si; t = 2, may c6 dang hoa thi bon canh, cho bigt phan lop orbital. Di8u nay se gidi thi8u trong phan s6 Wong tii tit dtioi day. t cho bie't c6 bao nhi8u mat nut dia ham song di qua hat nhan, xem Hinh 2.9. Nhu to da bi6t ci tren, mot trong so cac mat nut luon luon khoang cach r vo han toi hat nhan. Do d6 ma t bie'n thien tii 0 toi (n - 1). c. SO-lito'ng tet tee m Co hoc luong tit cho thy nhting orbital c6 ding gia tri t se c6 ding gia tri momen Ong Wong orbital M, nhung duoc phan b6 trong khong gian theo (2t + 1) phuong khac nhau. Cac pinking orbital nay duoc dac tiling bang s6 Wong tit tii m. Gia tri m &toe xac dinh flint sau. 75 Hinh 2.9. Vi trf dia cac mat nut d61 voi nhimg tang thai khac nhau dm electron Do M la dai Wong vectd, khi chieu cac vectd nay xueing met true, chang han truc z (hinh chieu caa M chi xac dinh tren met truc, vi theo nguyen 11 bat dinh Heisenberg thi cac hinh chieu khac khong the xac dinh dtioc) thi cac gia tri hinh chieu cua Chung, ki hieu Mz, duoc xac dinh bang he thifc: Mz = h m. 27c (2-46) day M, = gia tri hinh chieu cua momen &Ong Wong orbital, con goi la momen tit orbital ciia electron. m = so luting tit m c6 cac gia tri 0, ±1, ..., ±t. -2 -1 0 1 2 h z X 2n Hinh 2.10. Cac gia tri hinh chigu M, cUa momen tit orbital cilia cac electron có ding t = 2, cung M = r xuong truc z h , 27r h Thi du cac orbital c6 t = 2, c6 ciing momen orbital M = , nhUng 2t co 5 gia tri hinh chieu khac nhau Mzxuong truc z la: - 2—h ; --h ; 0; I —h ; 27r 27E rc 76 , 2 h . Dieu do c6 nghia c6 5 orbital deu co C = 2, nhung 5 orbital nay c6 5 2m piniong khac nhau duoc dac truing bang cac gia tri khac nhau cila m la - 2, - 1, 0, 1, 2 (xem Hinh 2.10). Toi day to thay trong lop orbital n c6 n2orbital la hien nhien. Bal vi ling vOi gia tri n xac dinh c6 n gia tri t. WA met gia tri C lai c6 (2t + 1) gia tri m tlic có (2f + 1) orbital. Thi du n = 2 c6 22= 4 orbital. n = 2 —> C = 0 —> m = 0 có orbital ku . 200 1 —> m = 01 - Y21-1 W210 W211 4 orbital d. So lu'cing tic' spin s. Orbital tam phtin Trong thuyet Bohr - Sommerfeld da de cap toi to hop 4 s6 ltiong tit n, f, m, s dac truing day dU cho ski chuyen &Ong cila electron theo cac qui dao xac dinh. Toi co hoc Wong tii, khi giai phuong trinh Schrodinger phi Wong deli (2- 39) cho nguyen tit hydro da thu duoc cac s6 Wong tii n, €, m, chtta thgy xugt hien s6 Wong tit this tui (s6 Wong tit spin) do do ti do this tut nhui da duoc goi la "spin" cila electron ma c6. Spin chInh la ski xoan, skf quay quanh truc cua . minh, hay ski ti1 . quay. Spin cila electron c6 dtioc la nha momen deng Wong von c6, con goi la momen rieng, momen spin cim no. Spin dm electron clang la met dac truing co ban giong nhui dien tich va khol Wong cila electron. Nam 1928, Dirac, nha vat 11 Anh da bleu chinh khol Wong hat theo thuyelt tutting doi Einstein, Ric nay phitong trinh Schrodinger trod thanh piniong trinh tutting d6i hod. Viec giai phuong trinh da thu duoc he thitc xac dinh momen spin cita electron: Ms= js(s+1) 27c (2-47) vOi s = —1 2 Ms= Momen spin cila electron. Hinh chieu Msxufing met truc, till du true z c6 4 lon Ms(z): Ms(z) = ms 27-c (2-48) 77 6 day MS(Z) = hinh chie"u cua vecto momen spin cila electron xu6ng true z. ms= s6 Wong tit spin. mschi c6 hai gia tri la ± s titc + 2 -1 va - -1 . Thing ngttcii ta ki hi6u s6 Wong tii spin la s thay cho ms. Momen d6ng Wong toan phan cim electron bang tang hai momen thanh phan: momen Ong luting orbital va momen spin. D6 lOn cUa momen ding lacing toan phan, ki hieu Mjduoc xac Binh bang so Wong tii j, goi la so-Wong tii n6i: M; Vj(j+1) h (2-49) 2 TC 6 day Mj= momen do, ng Wong toan phan cim electron. j= s6 Wong tit n6i = t + s = t + 2 1 Truang hop (C + -) duoc goi la hai momen thanh phan song song, con 2 1 - ) la hai momen thanh phan d6i song. 2 T6 hop 4 s6 Wong tit n, C, m, s m6 ta day du sit chuyen d'Ong cUa electron trong nguyen tii. Si chuye'n d6ng nay killing con mot dac tinh nao khac ma khong phu thu6c vao 4 so-luting tit nay. N6i khac di, to hop 4 s6 luting tit la di:6u ki6n can va du de mo ta trang thai dia. electron. 4 so-luting tit dac thing cho 4 d6 tit do cua electron. Cac orbital will., lien quan toi 3 d6 tit do dai ch6- trong kh6ng gian nen wrilmdtioc goi la orbital khong gian. Con do tit do this tU lien quan toi s nen orbital mo ta day du electron duoc goi la orbital toan phan, 1 1 2 phu thu6c vao n, m, s, duoc hieu iiintins. Do s c6 chi hai gia tri + 2 - va - - nen tang voi m6i orbital khong gian c6 hai orbital toan phan. Thi du orbital khong gian la kv210c6 hai orbital toan phan lava 210-2 210+ — 2 Nhtt vay trong lop orbital n c6 n2orbital kh6ng gian va 2n2orbital toan phan. Di'6u nay c6 nghia trong lop orbital n c6 the CO 2n2trang thai khac nhau titc c6 the c6 2n2electron. * Nang luting cila electron va quang ph6 phat xa cim nguyen tit hydro Theo Bohr cling nhii khi giai pinking trinh Schrodinger phi ttidng doi hod (2-39) duoc ding mot he thlic nang Wong cim electron trong nguyen tit hydro la: 27c2 me4 E°= h2n2 (Xem 2-44) Sau d6, vOi pinking trinh Schrodinger Wong dOi hoa ta duoc he thitc nang Wong cila electron trong nguyen tit hydro la: 78 Enj = — 2TE'me 4 1+ a21 1 3 n2h2 n J+1/2 4n, (2-50) 6 day Enj= nang Wong cUa electron trong nguyen tii hydro n = s6 Wong tit chinh h = hang s6 Planck j=so- Wongti nei = f, + s = C + 2 , goi la hang s6 c6u trot tinh vi. 2,7ce 2 1 a = hC 137 Theo (2-44) nang luong cila electron trong nguyen tit hydro dtioc xac Binh bang s6 Wong tii n,va khong phu thuec gi vao nhiing khong C, m, s. Nhti vay c6 nghia c6 the c6 met s6 trang thai khac nhau (nhiing trang thai nay c6 ding gia tri n nhung do ding s6 Wong tit C, m, s c6 gia tri khac nhau) c6 ding gia tri nang Wong. Hien ttiOng nay goi la su' suy Nen. Si suy hien hien mat khi nguyen dat trong dien trang hay tit tritang nao d6. Do hie nay cac electron trong cac trang thai ding n nhung cac gia tri C, m, s khac nhau chiu tac deng khac nhau cua dien tit trang ngoai, ket qua la nhung nang Wong trang thai nay tra nen khac nhau, tuan theo he thilic (2-50). Hien ti.tong nay goi la phan suy hien. Dieu nay giai thich dttoc sit phan giai cua cac vach quang pho (Oh met vach c6 the tach thanh met s6 vach sit nhau), khi ngu6n phat xa dat trong dien trang hay tit trilang. 1.3.6. eng dung phudng trinh Schrodinger vao nhang he gang hydro (chi có mot electron) Hien nhien moi dieu not v6 nguyen tit hydro hoan toan dp dung duoc doi vdi nhang he chi c6 met electron nhii He (Z = 2), Li2+ (Z = 3), Be3+ (Z = 4). Nang Wong dia electron trong nhcing truang hop nay la: = — 2Th2me4z2 h2 n2 -13,6 . Z2 (eV) n2 (2-51) Bieu fir& (2-51) tinh nang Wong cUa electron trong cac he giong hydro chi khac bleu thlic (2-9) tinh nang Wong cila electron trong nguyen tit hydro 6 ch8 la trong (2-51) c6 them dai Wong Z do Z > 1, con trong (2-9) khong c6 Z do hydro c6 Z = 1. S6 song cUa cac vach quang ph6 trong nhung tritong hop nay la: 1 = Rx .Z2 (1 — --,-) (cm-1) ng 2 n; (2-52) 79