Trng i Hc in Lc

Khoa i Cng

Chng 2.

Cc trng thi tp hp ca vt cht

Lin kt ha hcI

Tng tc gia cc phn t

Lin kt Hiro

II

II

III

Cc trng thi ca vt chtIV

I. Lin kt ha hc

1. Mt s i lng c lin quan n lin kt

a. m in ca nguyn t( )b. Nng lng lin kt:

l nng lng cn thit ph v mi lin kt v to ra cc nguyn t th kh . Nng lng lin kt thng k hiu E v tnh bng kcalo cho mt mol lin thng k hiu E v tnh bng kcalo cho mt mol lin kt. Nng lng lin kt cng ln th lin kt cng bn

c. di lin kt

l khong cch gia hai nhn nguyn t khi hnh thnh lin kt. di lin kt thng k hiu ro v tnhbng Ao = 10-8 cm

d. bi ca lin kt

S lin kt c hnh thnh gia hai nguyn t cho trc c gi l bi ca lin kt v k hiu l . bi ca lin kt cng ln th lin kt cng bn, nng lng lin kt cng ln v di lin kt cng nh.

e. Gc lin kt( gc ha tr)

l gc to bi 2 mi lin kt gia mt nguyn t vi hai nguyn t khc

e. phn cc ca lin kt, momen lng cc

Trong nhng lin kt gia hai nguyn t khc nhau, do c s chnh lch v m in, e lin kt b lch v pha nguyn t c m in ln hn, to ra y mt in tch m no (-), cn nguyn t kia mang mt n tch (+). Khi ngi ta ni lin kt b phn cc.cc.V d: HF, CO2

phn cc ca lin kt c nh gi qua momen lng cc , n v tnh l D phn cc ca lin kt ph thuc vo in tch trn cc v di ca lin ktS chnh lch m in gia hai nguyn t cng ln th lin kt gia chng cng phn cc.

f. Qui tc bt t

Tt c cc kh tr( tr He) u c 8 e lp ngai cng. Tt c cc kh tr( tr He) u c 8 e lp ngai cng. Chng rt t hat ng ha hc ( khng lin kt vi nhau v hu nh khng lin kt vi nhng nguyn t khc to thnh phn t. Cc kh tr tn ti trong t nhin di dng cc nguyn t t do.V vy cu trc 8 e lp ngai cng l mt cu trc c bit bn vng. Do cc nguyn t c xu hng lin kt vi nhau t c cu trc e bn vng ca cc kh tr

2. Cc dng lin kt ha hc

a. Lin kt ion

L lin kt gia hai ion tri du do lc ht tnh in to thnh.Trong lin kt ion, ha tr ca nguyn t bng s in tch ca ion vi du tng ng. V d: Na+ + Cl- NaClng. V d: Na+ + Cl- NaCl

Lin kt ion l lin kt bn , nng lng lin kt kh ln( 100kcal/mol).Lc ht tnh in gia cc ion khng nh hng, mt ion dng c tc dng ht nhiu ion m xung quanh n v ngc li. V vy ngi ta ni lin kt ion khng c nh hng. Nhng hp cht ion thng c dng tinh th bn vng

b. Lin kt cng ha tr

Theo Lewis, lin kt cng ha tr c hnh thnh gia cc nguyn t ca cng mt nguyn t ( =0) hay ca cc nguyn t c s chnh lch nh

Thuyt ca Lewis

nguyn t c s chnh lch nh v m in( nh).

Trong lin kt cng ha tr, cc nguyn t tham gia lin kt b ra 1,2,3 hay 4 e dng chung mi nguyn t t c 8e hay 2e lp ngoi cng.

V d: H2, N2, O2, CO2, HF, NH3

Thuyt MO( lai ha obitan nguyn t)

T nhng nghin cu v phng php lin kt ha tr ca Heitler, London, Pauling, Slater ngh s dng thuyt MO gii thch.

Lin kt cng ha tr c hnh thnh do s ghp i hai electron c thn c spin ngc chiu ca i hai electron c thn c spin ngc chiu ca hai nghuyn t, khi c s xen ph hai AO

Mc xen ph ca cc AO cng ln th lin kt cng bn, lin kt c thc hin theo phng ti s xen ph l ln nht

Thuyt MO( lai ha obitan nguyn t)

Trng thi ca e c m t bng cc MO. Mi MO

Phn t - t hp thng nht gm cc ht nhn v

cc electron ca cc nguyn t tng tc.

S nh hng lin kt. Lin kt v lin kt

Trng 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

Nng lng gn nhau.

Mc che ph ng k.

iu kin cc AO tham gia t hp tuyn tnh

Mc che ph ng k.

Cng tnh i xng i vi trc lin nhn.

S che ph cc m my e dc theo trc lin nhn lin kt ,nhn trc lin nhn lm trc i xng, l mt lin kt bn. Lin kt c th hnh thnh do s xen ph cc m my s-s, s-p, p-p

S che ph cc m my e v hai pha trc lin nhn lin kt c mt phng i xng cha trc nhn lin kt c mt phng i xng cha trc lin nhn, lin kt km bn hn lin kt . Lin kt

c th hnh thnh do s xen ph cc m my p-p,p-d

S to thnh cc MO t AO s

S to thnh cc MO,MO t cc AOp

Trong thuyt MO, ha tr ca nguyn t bng s e c thn ca nguyn t trng thi c bn hay trng thi kch thch

C Ha tr 2

C*

N

Ha tr 3

Ha tr 3

Lai ha sp

S t hp mt m my s vi mt m my p to ra 2 m my lai hng theo 2 hng trong khng gian. Trc ca 2 m my ny to ra gc 180o

Be

2s

Be*

2s 2p

Lai ha sp2

S t hp mt m my s vi 2 m my p to ra 3 m my lai hng theo 3 hng trong khng gian. Trc ca 3 m my ny to ra gc 120o

B

B*

Lai ha sp3

C

S t hp mt m my s vi 3 m my p to ra 4 m my lai hng theo 4 nh ca mt t din u. Trc ca cc AO ny to ra gc 109o28.

C*

C hai lin kt cng ha tr: Lin kt cng ha tr khng phn cc. Trong , cp e lin kt phn b u gia hai nguyn t. V d: H2, O2, N2, C H. Lin kt cng ha tr phn cc. Trong cp e lin kt b lch v pha nguyn t c m in ln hn.V d: HCl, HF, H2O, NH3V d: HCl, HF, H2O, NH3Lin kt cng ha tr tng i bn. Nng lng lin kt khong vi chc kcal/mol

c. Lin kt cho nhn

Lin kt cho nhn hay cn gi l lin kt phi tr c th xem l mt dng c bit ca lin kt cng ha tr. Trong lin kt ny cp e dng chung ch do 1 nguyn t a ra gi l cht cho, cn nguyn t kia c 1 obitan trng gi l cht nhn.V d: s hnh thnh ion amoni t phn t NH3 v H

+V d: s hnh thnh ion amoni t phn t NH3 v H+

H+ +

H

I. Tng tc gia cc phn t( Lc Van der Waals)

Lc tng tc gia cc phn t c c trng bng

nhng gi tr nng lng khc nhau ty thuc vo mc

c cc ca cc phn t tng tc.

Nhng phn t phn cc tn ti di dng nhng lng

cc c momen khng i u nh hng i vi nhau

bng cc u tch in ngc du. Tng tc ny gi l

tng tc nh hng. Nng lng ca n

kTrEh 6

4

3

2

: l momen lng cc phn tr: khong cch gia cc tm ca lng cc, k: hng s BoltzmanT: nhit tuyt i

Kh nng phn cc ca phn t do s dch chuyn cc

e di tc dng ca in trng ngoi c xc nh

bng phn cc ca chng. Nng lc tng tc cm

ng c xc nh nh sau:ng c xc nh nh sau:

6

22

rEcu

Mc d hai phn t khng cc c momen lng cc

bng khng, chuyn ng ca cc e bn trong phn t

lm xut hin tc thi momen lng cc nh khi

chng tin li gn nhau. Phn t ny vi momen lng

cc nh li gy ra mt lng cc cho phn t cnh

Nng lng hp dn gia cc phn t E l tng ca 3

dng nng lng trn: E hp dn phn t = Eh + Ecu + Ekt

okt hvr

E6

2

4

3

ho/2 l nng lng dao ng ca cc nguyn t OoK vi tn s vo

bn. Nng lng ny c gi l nng lng tng

tc khuch tn.

II. Lin kt Hiro

Nhit si ca

H2O,HF, NH3 c

im si cao hn d

on cho thy c

Nhit

on cho thy c

mt ngoi lc tng

tc, chnh l lin

kt Hiro

im si

Nu lin kt Hirdo xut hin nhng nguyn t O, N,

F( l nhng nguyn t c m in mnh, cp e b

ht lch v pha O, N, F. Tip tc nguyn t H ny li

b ht bi O, N, F k bn

Y- H + Y - H + Y- H + Y - H +

Lin kt Hdro c nng lng c 8 40 kj/mol. Lin

kt Hrro cng bn khi nguyn t phi kim lin kt

vi Hdro c m in cng ln v kch thc cng

nh

nh hng ca lin kt Hiro n tnh cht l,

ha ca cc cht

Lm tng nhit si, nhit nng chy,

nhit ha hi.

Lm gim in li ca axit

Gy bin i tan

Gy bin i khi lng ring ca nc.

Mt cht tn ti trng thi kh, lng hay rn mt iu

kin no ph thuc vo ng nng chuyn ng nhit

ca ht v th nng tng tc ca cc tiu phn

III. Cc trng thi ca vt cht

1. Trng thi kh:

ng nng chuyn ng nhit vt xa th nng tng

tc gia cc phn t. Cc phn t kh chuyn ng

gn t do chim tan b th tch bnh ng, chng va

chm n hi vi nhau v vi thnh bnh

1. Trng thi kh:

Trng thi ca mt cht kh c c trng bi 3 yu t: nhit ( T), p sut( p) v th tch( V). Phng trnh biu din mi tng quan ca 3 yu t ny c gi l phng trnh trng thi kh l tng

pV= nRT

Trong : n: s mol khp: p sut ca cht kh th tch VR: hng s kh = 0.082atm/mol hay =

Kh l tng l nhng kh tha mn iu kin: Kch thc khng ng k so vi thnh bnh Gia cc phn t khng c lc tng tc m ch c va chm n hi gia chng, cng nh vi thnh bnh.

pV= nRT R: hng s kh = 0.082atm/mol hay = 62400mmHG/mol hay = 8.314J/mol

Khi lm ngui cc cht trng thi kh hay nn cc cht kh tht mnh. Lc tng tc gia cc phn t bt u tri hn nng lng chuyn ng ca chng v nhit xc nh cht kh chuyn qua trng thi lng

2. Trng thi lng:

S khc bit gia ng nng chuyn ng nhit v th nng tng tc gia chng khng ln lm. Lc tng tc gia cc phn t cht lng ln hn gia cc phn t cht kh nhng cng ch ngn khng cho chng dhuyn ng hn lon ch cha ln ngn khng cho chng ngng hn s chuyn ng. V vy cht lng khng c hnh dng v cu trc xc nh

Cc tnh cht ca cht lng: tnh nht v sc cng b mt

Tnh nht: cc cht lng cn tr s chuyn ng ca chng.Nu gi F l lc cn thit lm dch chuyn lp cht lng ny so vi lp cht lng khc. F c tnh theo cng thc:

x

vSF

S: din tch tip xc gia 2 lp cht lngv: hiu s tc gia 2 lp cht lngx: khong cch gia 2 lp cht lng: h s nht, t l thun vi nhit

Sc cng b mt ( ): cc phn t nm su bn trong cht lng v cc phn t nm bn trn b mt cht lng chu lc ht khng ging nhau.

Phn t su c bao bc bi cc phn t khc t mi pha v cc lc tc dng ln n cn bng nhau.

Cc phn t lp mt chu lc tc dng t cc Cc phn t lp mt chu lc tc dng t cc phn t lp trong v c xu hng b ht vo trong. V vy ton b b mt trng thi cng.

Sc cng b mt c c trng bng cng tiu tn lm tng din tch b mt ln 1cm2

n v tnh ca l (dyn/cm) hay erg/ cm2

3. Trng thi rn

Khi chuyn qua trng thi rn, khong cch gia cc phn t tr nn nh hn, lc tng tc gia chng mnh hn. Do cht rn c th tch v hnh dng khng i. Cht rn c c trng bi 2 trng thi tinh th v v nh hnh.

Cht rn tinh th

l nhng cht c th t kt tinh thnh cc tinh th

c hnh dng xc nh. Bn trong tinh th cc nguyn

t, phn t, ion c sp xp theo mt trt t xc

nh. Trt t ny quyt nh hnh dng v tnh i nh. Trt t ny quyt nh hnh dng v tnh i

xng ca tinh th.

Cht tinh th c nhit nng chy xc nh v

khng i trong sut qu trnh nng chy.

Cht tinh th c tnh bt ng hng

Cc kiu mng tinh th

Da vo bn cht ca cc tiu phn nt mng v lc lin kt gia chng, ngi ta chia mng tinh th thnh 4 kiu chnh: mng nguyn t, mng phn t, mng ion, mng kim loi

Mng nguyn t:

Mng nguyn t c to thnh t nhng lin kt vi nhau bng lc lin kt cng ha tr. Quy lut phn b cc nguyn t trong mng tinh th c quyt nh bi kiu lai ha cc orbital ca nguyn t

S phi tr( s tiu phn bao quanh gn nht i vi ion trung tm) ca nguyn t bng s lin kt to ion trung tm) ca nguyn t bng s lin kt to thnh bi cc nguyn t.

V d: kim cng, Si, Ge, ZnS

Mng phn t

Mng phn t c cc tiu phn cu trc l nhng phn t( i vi kh tr l nhng nguyn t), chng ht nhau bng lin kt yu Vander Waals. Do , cht c mng phn t d nng chy, d bay hi, mm v d tan.V d: H , O , N , kh tr, CO rnV d: H2, O2, N2, kh tr, CO2 rn

Mng ion

Mng ion c to thnh t nhng ion ngc du lun phin nm ti cc nt mng v lin kt vi nhau bng lc ht tnh in.Mng ion c s phi tr cao( do lin kt ion khng bo ha v khng nh hng), mi mt ion c bao quanh bi nhiu ion ngc du, nn ton b tinh th ion cng l mt phn t khng l bn vng c nhit si, nhit nng chy kh cao, cng ln, d tan v in ly mnh trong nc.V d: Nacl, mui hlogenua ca kl kim

Mng kim loi

Mng kim loi c c trng bng cc ion dng nm ti nt mng v lin kt gia chng l lin kt kim loi.

Trong tinh th kim loi cc Trong tinh th kim loi cc nguyn t c khuynh hng sp xp th no cho st sao nht. Mng kim loi c s phi tr rt cao

Mng kim loi c 1 trong 3 kiu: lc phng, lp phng tm din v lc phng tm khi.

Cht rn v nh hnh

L nhng cht rn khng th kt tinh thnh nhng tinh th c hnh dng xc nh. Trong cht v nh hnh cc phn t sp xp hn n. Chng khng c nhit nng chy nht nh. Khi b un nng chng mm dn n trng thi chy, sau bin thnh cht lng hon n trng thi chy, sau bin thnh cht lng hon ton. Cht v nh hnh c tnh ng hngV d: thy tinh, cao su