LIN KT ION

Thuyt tnh in v lin kt ionTng tc ha hc xy ra gm hai giai on:Nguyn t truyn electron cho nhau to thnh ionCc ion tri du ht nhau theo lc ht tnh in Na + Cl Na+ + Cl NaCl 2s22p63s1 3s23p5 2s22p6 3s23p6

Mt s c cu bn ca ionns2np6 F- , Cl- , O2- , Na+ , Mg2+, Al3+ns2np6nd10 Ag+ , Cu+ , Zn2+ (n-1)s2 (n-1)p6 (n-1)d10ns2 Pb2+, Bi3+, Tl+..(n-1)d5 Fe3+

Kh nng to lin kt ion ca cc nguyn tKh nng to lk ion ph thuc vo kh nng to ion ca cc ngt:Cc ngt c I d to cation (IA,IIA )Cc ngt c F mnh d to anion (F- ,Cl-, ClO4-, NO3- , SO42-) ion

Tnh cht ca lin kt ion Khng nh hngKhng bo haPhn cc rt mnh

Mng tinh th ionNguyn tc sp xp cc ion c kht nhtMi ion c bao quanh s cc i cc ion tri du (s phi tr).Cc ion cng du cch xa nhau cng nhiu cng tt.

Quyt nh kiu cu trc tinh th l

Kiu lp phng tm khi s phi tr l 8 CsCl, CsBr, CsIKiu lp phng tm din S phi tr l 6NaCl, CsF, MgOKiu ZnS kiu blende km- Wutzite S phi tr l 4 BeO, ZnO, AgI

Nng lng mng tinh th ion

MX (tinh th ion ) M+(kh) + X- (kh) H=UMXCng thc Kapustinski (lk ion thun ty)

Khi lk c phn cng ha tr tng i ln th cng thc ny khng cn chnh xc.

Nng lng mng tinh th bn mng tinh thKh nng ha tanNhit siNhit nng chy

Nng lng mng tinh th

bn mng tinh thKh nng ha tanNhit siNhit nng chy

QUAN H GIA NNG LNG MNG LI V NHIT SI, NHIT NNG CHY

MgO Tnc = 2852oC Mg2+ O2-NaCl Tnc = 800oC Na+ Cl- Tnc ~ U m U ~ Zc Za ; U ~ 1/rc+ra

So snh nhit nng chy NaCl v MgOU (MgO) 4 U(NaCl) nn Tnc(MgO) 3.6 Tnc (NaCl)

c im ca hp cht ionTnh dn in km trng thi rn nhng dn in tt trng thi nng chy hay dung dch.Nhit nng chy, nhit si kh caoTinh th rn, gin.D tan trong cc dung mi phn cc (H2O).

Qu trnh ha tan cc cht tinh th ion trong dm phn cc MX(rn) +(n+m) H2O M+.nH2O + X-.mH2O Hha tan = Hvl + Hsol

Hvl >0 Hvl UMX

Hsol

QU TRNH VT L , Hvl >0QU TRNH HYDRAT HO , Hhy < 0

QUAN H GIA NNG LNG MNG LI NNG LNG HYDRAT HO V TAN

S phn cc ion

Khi nim v s phn cc ionCc yu t nh hng n s phn cc ionnh hng ca s phn cc ion n tnh cht cc hp cht

S phn cc tong h gia cc ion (pt)= - c - a_ +_ +

_ +_ + _ +_ +

+_ c ac v a l momen lng cc cm ng

l momen lng cc ca hai ion ( xem lk ion l tng )

Momen lng cc cm ng = .E a = a.Ec c = c.Ea - phn cc, r3 a >> cE cng in trng ca ion gy phn cc. cation c tc dng gy phn cc mnh hn anion

>>Qa trnh phn cc ion c tnh cht mt chiu cation gy phn cc anion

s phn cc ion lm cho m my in t ca cation v anion che ph nhau mt phn nn lk ion bao gi cng mang mt phn tnh cng ha tr. Khng c lk ion 100%._

CC YU T NH HNG N S PHN CC ION phn cc Tc dng gy phn cc ca cation

Cc yu t nh hng n phn cc Bn knh ion cng ln tng F - < Cl - < Br - < I- tng Cc ion ng electron c in tch cng nh (cng m) th tng. Mg2+ < Na+ < Ne < F- < O2- tng

Cu hnh electron ha trns2np6 < ns2np6nd19 < ns2np6nd10 tng

phn cc ca cc cation

phn cc ca cc anion

Tnh cng ha tr tng dn

Cc yu t nh hng n tc dng phn cc ca cationTh cation (qui tcFajan) Cu hnh electron ha tr ns2np6 < ns2np6nd19 < 18e+ ns2< ion kiu He < ns2np6nd10(cc ion c cng in tch, bn knh tng ng )

Tnh cng ha tr tng dn

nh hng ca s phn cc ion n tnh cht ca cc hp cht in ly bn nhitNhit si v nhit nng chy tan

in ly

Tnh cng ha tr tngTnh ion gim in ly gim

S phn cc ion tng

bn nhit S phn cc ion tnh cht tnh ion bn nhit ca tinh th ion Tnc, Tply

tan Hha tan= Hvl + Hs = U + EhNng lng mng tinh th U cng ln tan Kh nng phn cc nc ca cation ( q+/r+) tng lc ht tnh in gia cation v lng cc nc Eh cng m tan

MuiCaSO4SrSO4BaSO4 tan8.10-35.10-41.10-5U (kJ/mol)234723392262Eh (kJ/mol)-1703-1598-1444

Tnc 8450C 6050C 5500C 4490C LiF LiCl LiBr LiITnh cng ha tr tng dn tan trong nc gim dn tan trong etanol tng dn

in tch bn knh Tnc[0C] tan Lin kt

NaCl 1+ 0.095nm 808 Tan ionMgCl22+ 0.065nm 714 Tan ionAlCl3 3+ 0.050nm 180 Thy phn chtrSiCl4 4+ 0.041nm -70 Thy phn chtr

GREATER POSITIVE CHARGE DENSITY

LiClrCl-167 pmTnc 613oCLiBrrBr-182 pmTnc 547oCLiIrI-206 pmTnc 446oC

Ca2+3s2 3p6 Hg2+ 5s25p65d10 r(Ca2+) = 114 pm; r(Hg2+) = 116 pm Tnc (HgCl2)= 276oC