3.Lien Ket Cong Hoa Tri VB.pp

5/21/2018 3.Lien Ket Cong Hoa Tri VB.pp

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CHNG III

LIN KT HA HC V

CU TO PHN T

CHEMICALBONDING
http://www.chem.tamu.edu/class/fyp/Movies/03M05AN3.MOV


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BN CHT CA LIN KT

Electron ho tr- ns (s), ns np(p) , (n -1)d ns(d),

(n-2)f (n -1)d ns(f)

Lin kt ho hc c bn cht in (lc ht)


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MT S C TRNG LIN KT

di lin kt

Gc ha tr

Bc lin kt

Nng lng lin kt

ng cong th nng


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NG CONG TH NNG CA H2

Khong cchgia hai nhn

Thnng

y (+)

Ht (-)

0

Hnh thnh lin kt


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DI LIN KT L khong cch gia hai ht nhn cu hai

nguyn t to lin kt.

di

lin ktca H2l74pm
http://www.chem.tamu.edu/class/fyp/Movies/09M09AN4.MOVhttp://www.chem.tamu.edu/class/fyp/Movies/09M09AN4.MOVhttp://www.chem.tamu.edu/class/fyp/Movies/09M09AN4.MOVhttp://www.chem.tamu.edu/class/fyp/Movies/09M09AN4.MOVhttp://www.chem.tamu.edu/class/fyp/Movies/09M09AN4.MOVhttp://www.chem.tamu.edu/class/fyp/Movies/09M09AN4.MOVhttp://www.chem.tamu.edu/class/fyp/Movies/09M09AN4.MOV


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NNG LNG LIN KTH2(k) H(k) + H(k) H= Elk= 436kJ/mol

Nng lnglin kt
http://www.chem.tamu.edu/class/fyp/Movies/09M09AN3.MOVhttp://www.chem.tamu.edu/class/fyp/Movies/09M09AN3.MOVhttp://www.chem.tamu.edu/class/fyp/Movies/09M09AN3.MOVhttp://www.chem.tamu.edu/class/fyp/Movies/09M09AN3.MOV


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BC LIN KT

L s lin kt to thnh gia hai nguynt tham gia lin kt.

Acrylonitrile

Lin ktnLin kti

Lin ktba


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Lin kt dlk(pm) Elk (kJ/mol)

C -C 154 346C = C 134 610C C 120 835

N -N 145 163N = N 123 418N N 110 945

Bclin ktcng lnth lin ktcng bnv chiudi lin ktcng ngn.


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GC HA TR(ABnn2 )


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CC LOI LIN KT

Lin ktcngho trtheo chclngt

Lin ktion Lin ktkim loi

Lin kthydro

Lin ktVanderwaals


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Atomic Orbitals Molecules

LIN KT CNG HA TRTHEO C HC LNG T


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1.VALENCE BOND THEORYLinus Pauling

PHNG PHP LIN KT HA TR(PHNG PHP VB)

Mang ngha nh tnh


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2.MOLECULAR ORBITAL THEORY

Robert Mullikan (1896-1986)

PHNG PHP ORBITAL PHN T(PHNG PHP MO)

Mang ngha nh lng


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PHNG PHP LIN KT HA TR (VB)

*Quan nim v lin kt cng ha tr theo VB

*Cc loi lin kt cng ha tr v bc lin kt

*Cc tnh cht ca lin kt cng ha tr


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1 2

a b

Phng trnh sng Schrodinger:

Hm sng m t chuyn ngng thi cu hai electron

Bi ton phn t H2

0VE

h

m8

zyx

2

2

2

2

2

2

2

2

E0

a

s

rab

+ ++

TO LIN KT

ng cong th nng theo l thuyt VB

rab


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LunimcbncuthuytVB

Lk cht c s trn cp e (pp cp e nh ch - lk 2e 2tm)Lk cht c hnh thnh do s che ph ca cc AO ha tr

(che ph dng )


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LUN iMC BN CA PP- VB

iu kin to lin kt cng ha tr bn:

Cc AO c nng lng xp x nhau

Cc AO c mt e lnCc AO c cng tnh nh hng

Lin kt cng bn khi mt che ph ca ccAO cng ln

Biu din lk cht nh sau H :H hocHH


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1.C CH GHP I : +

Kh nng to lk c quyt nh bi s AO

ha tr cha e c thn

Ch : s e c thn c th tng ln nh kch thch

Nguyn t C C*

S di chuyn in t trong qu trnh kch thch

thng xy ra trong cng mt lp.

C CH TO LIN KT CNG HA TR

2s2 2p2 2s1 2p3


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C CH CHO NHN+

Cht cho Cht nhn

Kh nng to lk c quyt nh bi s v s

AO trng c th c khi ng t trng thi kch thch

V d O: 2s2 2p22p12p1 O*:2s22p2 2p2 2p0


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Khnngtolin ktcht (theo chai cch)

cquytnh bisAO ha trcanguyn t:

- Cc nguyn tchu kI c 1 AO ha tr totia1 lk cht

- Cc nguyn tchu kII c 4 AO ha tr totia4 lk cht

- Cc nguyn tchu kIII c 9 AO ha tr totia9 lk cht

Lin kt cng ha tr c tnh bo ha


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TNH CHT LIN KT CNG HA TR

Tnh bo ha

S lin kt CHTcc i = s AO ha trca nguyn t.

Tnh nh hng

Tnh c cc v khng cc

S h li kt h t


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S phn cc ca lin kt cng ho tr

FF HCl Na Cl

F= F H< Cl Na


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Cc loi lin kt cng ha tr v bc lin kt

Ch : cc vng xen ph phi cng du


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Lin kt Sigma ()

Cc AO che ph dc theo trc lin kt

Nhn trc lin kt lm trc i xng.

Lin kt khng lm cn tr s quay t docu cc nguyn t quanh trc lin kt

bn(ns-ns)< (ns-np) < (np-np)

+

++

++ +- - -

+ +


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Lin kt Pi ()

Hai AO che ph hai pha cu trclin kt.

C mt phng phnxng cha trc linkt. Trc lin kt

++

__


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Lin kt

Cc nguyn t thuc chu k 2 c kh nngto lk 2p-2p hoc 2p-3p

Cc nguyn t thuc chu k 3 tr i ch ckh nng hnh thnh lin kt p-d , d-d

S lin kt (ghp i)= (s oxh)nttts lk


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Lin kt nLin kt n lun lun l lin kt


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Lin kt bi

Trong lin kt bi th s c 1 lin kt phn cnli s l cc lin kt


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Lin kt khng nh ch

Cp electron lin kt khng thuc hnv mt cp nguyn t no c m phnb ng u cho mt s ht nhn

nguyn t k cn.

B

Cl

Cl Cl

:

::

1/3

1/3 1/3


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Lin kt

Lin kt c to thnh khi hai AOdche ph bng tt c bn cnh.

Lin kt thng gp trong phc chtca kim loi chuyn tip hoc mt shp cht ca cc nguyn t thuc chu

k 3.


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Lin kt ca cc AO d

Z

Y

X

Z

Z

Z

Y

Y

Y

X

X

X


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BC LIN KT

BC LK = 1(lk)+s lkc+s lk kc/scpngt

Bc lin kt c th l s l khi c mt lin kt

khng nh ch

LIN KT CNG HA TR CA H S


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LIN KT CNG HA TR CA H2S


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V sao gc ha tr khng l 900?


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THUYT SC Y CP IN T HA TRValence Shell Electron Pair Repulsion(VSEPR )

Trong phn t cng ho tr ABncc cpin t ha tr lin kt () v cp in t

ho tr t do cu A (nu c) phi xa nhau mc ti a sao cho lc y gia cccp electron c gi tr nh nht.


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nh hng trong khng gian cu cc cpe lin kt() hoc e t do quanh A

2 charge clouds,

linear 3 charge clouds,trigonal planar

4 charge clouds,tetrahedral

Nguyn tA phi trngthi lai ha.

Scpe quanh A squytnhtrngthi lai hacanguyn ttrung tm A .


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Lai ha l g ?

Nguyn t trung tm A s dng cc AOha tr: s,p,d,f..trong ni b nguyn tem pha trn vi nhau to thnh cc

AO lai ha.Cc AO lai hany s tham gia to lk

vi B hoc cha in t t do ca A.


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c im cc AO lai ha

S cp e(td+lk)quanh A =S AO tham gia lai ho= s AO lai ho.

AB2,s cp e quanh A = 2 A lai ha sp , 2AO lh sp

Phn b i xng vi nhau trong khng gian

Cc AO lai ho c mc nng lng bng nhau


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Cc AO lai ha c kch thc hnh dng ging

nhau, mt electron dn v mt pha.Cc AO lai ha cu A to lkvi B bn hn

so vi AO khng lai ha


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iu kin lai ha bn

Nng lng ca cc AO tham gia lai ha xpx nhau

Mt e ca cc AO tham gia lai ha ln

Mc che ph cu cc AO phi cao


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Trong mt chu k: Ens - np nn kh nng Lai Ha

Li Be B C N O F Ne

E2p2s 1,9 2,8 5,7 8,1 11,4 18,9 22,6 26,8

Trong mt phn nhm chnh: r kh nng LH


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S cp e quanh A = s cp etd+ s cp elk= 2 A:sp lai ha thng

= 3 A:sp2 lai ha tam gic= 4 A:sp3 lai ha t din

S cp e quanh A= 1/2{ (eht)ABn-8(2)n}+n

n 2 A khng l cc kl chuyn tip

V d: BeCl2 - s cp e quanh Be = (16-8.2) +2=2

Besp

Lai ha sp


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Lai ha sp S cp e quanh A= 2 A trng thi lai ha SP

AB2 dng thng gc lk 1800

linear


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LAI HO SPA * 2s1 2p1


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Lai ha sp

BeCl (AB E ) BLK=1; 1800


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BeCl2 (AB2E0) BLK=1; 1800s cp e quanh Be= (16 8.2)+2=0+2=2sp

Be: 2s2 2p0

Be* 2s1 2p1

Lai ho sp

Hai AO lai ha ca Be

Cl: 3s23p5

Cl: 3s23p5

sp

L i h 2


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Lai ha sp2S cp e quanh A= 3 A trng thi lai ha SP2

AB3E0,AB2E1 - gc ha tr 1200

trigonal planar


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LAI HA SP2

Lai ha sp2


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Lai ha sp2

BCl (AB E ) BLK = 1 33 ; 1200


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BCl3 (AB3E0) BLK = 1,33;1200s cp e quanh B= (24-8.3)+3=0+3=3sp2

B: 2s22p1

Cl

Cl

Cl3p

Cl : 3s23p5

Cl : 3s23p5

Cl : 3s23p5

B* : 2s1 2p2

Ba AO lai ha sp2 ca B

sp2

Lai ha sp3


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Lai ha sp3S cp e quanh A= 4 A trng thi lai ha SP3

AB4 E0 , AB3E1, AB2E2 - gc ha tr 109028

tetrahedral


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LAI HA SP3


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CH4 (AB4) blk=1 ; 1090 5


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CH4 (AB4) blk 1 ; 109 5s cp e quanh C= (8-2.4)+4=0+4=4sp3

C : 2s2 2p2

C* : 2s1 2p3

H H H H

sp3

NH


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NH3 (AB3E1) blk=1 ; HNH=1070 3s cp e quanh N=1/2(8-2.3)+3=1+3=4sp3

N : 2s2 2p3

H H H

sp3

Cp e t do

Thp tam gic

H O (AB E ) blk=1 ; HOH= 1040 5


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H2O (AB2E2) blk=1 ; HOH= 104 5s cp e quanh O= (8-2.2)+2=2+2=4sp3

O : 2s2 2p4

sp3

H H

Gc


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2elk2elkLc y

2etd2etdLc y

2etd2elkLc y

> >

nhhngcacpinttdongc ha tr

nh hng ca cp in t t do


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2elk2elkLc y

2etd2etdLc y

2etd2elkLc y

> >

nh hng ca cp in t t do

Momen lng cc v phn t cht c cc


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Momen lng cc v phn t cht c cc

H F

electron richregion

electron poorregion

Momen lng cc m= x

: in tch [n v tnh in]

:khong cch gia hai in tch [cm]


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IU KIN PHN T CNG HA TR C CC

Lin kt cngha trc ccCutaphn tkhng ixng


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Momen lng cc cu phn t l tngvect momen lng cc cu cc linkt v cp electron ho tr t do trong

cc AO lai ha c trong phn t.


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C h kh ?


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C cc hay khng cc?

BF3, Cl2CO, v NH3.

Ph t kh BF


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Phn tkhng cc,BF3F

F F

BNguyn t Bb phn ccdng vnguyn t Fb

phn cc m.

Lin kt BF trong pt BF3 lc cc.

Nhngphn tc cutoixngnn khng cc.

M l l P l it HBF


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Molecular Polarity, HBF2

B b phn ccdng nhngH & F b phncc m.

H

F F

B

Lin kt BF v BH trongHBF2l c cc. Nhng do ptkhng i xng nn c cc.

u s u e


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u s u eEthylene

Lin kt CF phn cc mnh hn linkt CH.

Do c hai lin kt CF cng mt pha,phn t c cc.

u u e


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u u eEthylene

Lin kt CF phn cc mnh hn lin

ktCH. Do c hai lin kt CF nm hai pha

i nhau , phn t khng phn cc

T h ht t h t


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Tnh cht t ca phn t

- Chtthunt(Paramagnetic):chtcelectron cthn .Chtny khi ttrong ttrngsbnam chm ht.- Chtnghcht(Diamagnetic):chtkhng cin t c thn Cht ny khi t trong t trng

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3.Lien Ket Cong Hoa Tri VB.pp