Two Theories of BondingMOLECULAR ORBITAL THEORY Robert Mullikan (1896-1986) THUYT MOPhng php orbital phn t (MO)

Tnh thun t cu O2

L thuyt orbital phn t lin kt cng ha tr c to thnh t s t hp tuyn tnh cc AO to thnh cc MO. Khng c in t c thnNghch tBt li cu thuyt VB

LIN KT CNG HA TR THEO PHNG PHP MOBi ton ion H2+Quan nim ca phng php MOCc lun im c s ca phng php MOc. p dng phng php MO cho cc phn t bc hai

Bi ton H+Th nng ca electron :Hm sng phn t (MO) m t chuyn ng ca mt electron trong ion H2+ Orbital phn t (MO) lin ktOrbital phn t (MO) phn lin kt

T hp tuyn tnh cng c tc dng lin kt,nng lng thp hnMOlk(1S)

T hp tuyn tnh tr c tc dng phn lin kt, nng lng cao hn MOplk(1S*)

MO lin kt MO phn lin kt Nng lng thp hn Nng lng cao hn Bn Khng bn Mt e gia Mt e gia hai nhn tng hai nhn gim

Gin nng lng to thnh cc MO t cc AO (S) trong ion H2+1s - MO lin kt, c nng lng thp hn nng lng AO ban u

Quan nim ca phng php MOPhn t l mt nguyn t phc tp a nhn.M t s chuyn ng ca tng electron ring bit bng hm orbital phn t (MO)

Cc lun im c s ca phng php MOTrng thi ca e c m t bng cc MO. Mi MO c xc nh gn ng bng phng php t hp tuyn tnh cc orbital nguyn t MO = Ci AO S MO to thnh bng s AO tham gia t hp tuyn tnh

Phn t - t hp thng nht gm cc ht nhn v cc electron ca cc nguyn t tng tc.

iu kin cc AO tham gia t hp tuyn tnh

Nng lng gn nhau.Mc che ph ng k.Cng tnh i xng i vi trc lin nhn.

S che ph cc AO dc theo trc lin nhn MO MO nhn trc lin nhn lm trc i xng

S che ph cc AO v hai pha trc lin nhn MO MO c mt phng phn xng cha trc lin nhnNng lng cc MO ph thuc vo nng lng AO v mc che ph gia cc AO .

S to thnh cc MO t s t hp tuyn tnh cc AO ca phn t bc hai AO + AO MO lin kt (, ), EMO < EAO

AO - AO MO phn lin kt (* ,* ), E MO* > EAO

AO MO khng lin kt (0, 0 ), EMOo = EAO

S to thnh cc MO t AO s

S to thnh cc MO,MO t cc AOp

Mi MO ch cha ti a 2 e c spin i song.

Trng thi cu cc e trn cc MO c c trng bng cc s lng t phn t || v tng ng ging nh s lng t v m trong nguyn t.Cc e sp xp vo cc MO tun theo nl vng bn, nl ngoi tr Pauli, quy tc Hund.

Trong nguyn t Trong phn t = 0, 1, 2, 3 || = 0, 1, 2, AO: s, p, d, f .. MO: , , , ..

m = 0, 1, 2, .. = 0, 1, 2, ..

Cc c trng lin ktLk c quyt nh bi cc e lk m khng b trit tiu.Mt bc lk ng vi mt cp e lk khng b trit tiuCho lk 2 tm: Bc lk Tn ca lk c gi bng tn ca cp e lk khng b trit tiuBc lk tng th nng lng lk tng cn di lk gim

Thuyt MO coi s hnh thnh lin kt ha hc l s chuyn in t (ha tr) t cc AO cu cc nguyn t tng tc v cc orbital phn t thuc chung ton b phn t.

Vic m t cu trc phn t gm cc bcBc 1: Xt s to thnh MO t cc AOBc 2: Sp xp cc MO theo th t nng lng tng dnBc 3: Xp cc electron vo cc MOBc 4: Xt cc c trng lin kt

Cc phn t bc hai thuc chu k 1 1S 1S 1s , 1s* E : 1s < 1s*

cc phn t bc hai thuc chu k 1

AOMOAOHH2H1sNng lng1s H2 : [(1s)2] Bc lin kt = 1 Nghch t

AOMOAOHeHe2He1sNng lng1s Bc lin kt = 0 Khng tn ti

AOMOAOHe He2+ He+1sNng lng1sHe2+:[(1s)2(1s*)1] Bc lin kt = Thun t

p dng phng php MO cho cc phn t bc hai chu k haiCc phn t hai nguyn t ca cc nguyn t cui chu k II Cc phn t hai nguyn t cng loi ca nhng nguyn t u chu k IICc phn t hai nguyn t khc loi ca nhng nguyn t chu k II

Cc phn t bc hai thuc chu k 2(trc x l trc lin nhn )

1S 1S 1s , 1s* 2S 2S 2s , 2s* 2px 2px 2px , 2px* 2py 2py 2py , 2py* 2pz 2pz 2pz , 2pz*E : 1s< 1s*

Cc phn t bc hai u chu k 22s = C1(2SA+ 2SB) + C2(2PA + 2PB) C2

Gin nng lng cc MO ca cc phn t A2 thuc u chu k 2

Cc pt hai ngt ca cc ngt u chu k II

MOLi2Be2B2C2N2N2+Tong so e6(2)8(4)10(6)12(8)14(10)13(9)2px*2py*, 2pz* 2px2py, 2pz 2s*2s1s*1sBac lien ket101232,5Chieu dai lk (A0)2,671,591,241,101,12NL lien ket (kJ/mol)105289599940828T tnhnghchthuannghchnghchthuan

Cc pt hai ngt cng loi ca nhng ngt cui ck II

MOO2+O2O2F2F2Ne2Tong so e15(11)16(12)17(13)18(14)19(15)20(16)2px*2py*, 2pz* 2py, 2pz 2px2s*2s1s*1sBac lien ket2,521,510,50Chieu dai lk (A0)1,121,211,261,41NL lien ket (kJ/mol)629494328154T tnhthuanThuanthuannghchthuan

Phn t nh nguyn t d nhn Nguyn t m in hn s c nng lng thp hnv ng gp ch yu vo MO lin kt

Xt phn t CO

C c 6 electronsO c 8 electrons

HeteronuclearCOBc lin kt(10 4)/2 = 3

Cc pt hai ngt khc loi ca nhng ngt chu k II

HF

HF

HF

HFBond order: (2 0)/2 = 1Non-bonding electrons

LIN KT KIM LAICc tnh cht ca kim loi

Khng trong sutC nh kimDn nhit, dn in ttDo

Cu to kim loi v lin kt kim loi Nhng ion dng nt mng tinh thCc electron ha tr t do chuyn ng hn lon trong ton b tinh th KL kh electron

Thuyt min nng lng v cu to kim loi

MIN HA TR - HOMO min cha electron ha trMIN DN LUMO min nm trn min ha trMIN CM l khong cch gia hai min trn nu c

Cht cch inE > 3 eVCht bn dn0,1< E