CHNG III LIN KT HA HC

III.1. M u 1.1. Khi nim v lin kt ha hc: Lin kt ha hc l s kt hp gia cc nguyn t to thnh phn t hay tinh th bn vng hn.- Khi c s chuyn cc nguyn t ring r thnh phn t hay tinh th tc l c lin kt ha hc th nguyn t c xu hng t cu hnh bn vng ca kh him.Kh him tn ti trong t nhin di dng t do ring r, nguyn t ca chng khng lin kt vi cc nguyn t khc.Cu hnh vi 8e lp ngoi cng ca kh him (hoc 2e i vi He) l cu hnh e bn vng

1.2. Quy tc bt t Ni dung: Theo qui tc bt t (8e) th nguyn t ca cc nguyn t c khuynh hng kin kt vi cc nguyn t khc t cu hnh e bn vng ca kh him vi 8e ( hoc 2e i vi He) lp ngoi cng.Vi qui tc bt t ngi ta c th gii thch mt cch nh tnh s hnh thnh cc loi lin kt trong phn t, c bit l cch vit CTCT ca mt s hp cht thng thng.V phn t l mt h phc tp nn trong nhiu trng hp qui tc bt t t ra khng y .

III.2. CC C TRNG C BN CA LIN KT HA HC2.1. Nng lng lin ktNng lng ca mt lin kt ha hc bng nng lng cn cung cp cho phn t lm t lin kt .(thng c qui v 1 mol lin kt - kJ/mol hoc kcal/mol). EH-H = 103 kcal/mol : H2 2H H = 103 kcal/mol

2.2. di lin kt di lin kt l khong cch gia hai ht nhn ca nhng nguyn t lin kt vi nhau.V d: Trong phn t nc, dO-H = 0,94 .

Gia hai nguyn t cho trc di lin kt gim khi bc lin kt tng.

Lin ktC C C = C C C E(kcal/mol)83 143 194 d (A0) 1,54 1,34 1,2

2.3. Gc ha tr (gc gia hai lin kt)-L gc to bi hai na ng thng xut pht t mt ht nhn nguyn t v i qua ht nhn ca hai nguyn t lin kt trc tip vi nguyn t V d: gc HOH = 104028 Gc lin kt ph thuc vo: + Trng thi lai ha ca nguyn t trung tm. + m in ca nguyn t trung tm A v phi t X

nh nghaKhi nhng hoc thu thm electron nguyn t tr thnh phn t mang in gi l ionIII.3. LIN KT ION 3.1 S to thnh ionIon dngIon mIon

Ion dng S to thnh ion Natri t nguyn t Natri11+11++Nguyn t Na :1s22s22p63s1 in tch : 0 Ion Na+ : 1s22s22p6 in tch : 1+

Qu trnh trn c th c biu din bng phng trnh nh sau: Na Na+ + e TNG QUT: M Mn+ + neVi M : Kim loi n=1;2;3

Ion m S to thnh ion clo t nguyn t clo17+17++Nguyn t Cl: 1s22s22p63s23p5 in tch : 0 Ion Cl- : 1s22s22p63s23p6in tch : 1-

Qu trnh trn c th c biu din bng phng trnh nh sau:Cl + e Cl-TNG QUT:X + me Xm-Vi X : phi kim m = 1;2;3

III.3. LIN KT ION 3.2. Bn cht ca lin kt ion.Cl: 1s22s22p63s23p5 V d: xc nh s hnh thnh lin kt ion trong phn t NaClNa+: 1s22s22p6+Na: 1s22s22p63s1-Cl: 1s22s22p63s23p6

Lin kt ion l lin kt c hnh thnh bi lc ht tnh in gia cc ion mang in tch tri du.Vy bn cht ca kin kt ion : l lc ht tnh in Qu trnh trn c th c biu din bng phng trnh sau:2Na + Cl2 =2 NaCl2*1e

3.3. Yu t nh hng n s hnh thnh lin kt. 3.3.1.Nng lng ion ha Quy lut: + I1 < I2

3.3.3. Nng lng mng li tinh thL nng lng ta ra khi cc ion kt hp vi nhau to thnh mng li tinh th.Nng lng mng li cng ln th hp cht ion c to nn cng bn.Tm li: Kim loi cng d nhng eletron, phi kim cng d nhn electron, cc ion c to thnh ht nhau cng mnh th cng thun li cho s to thnh ion.

III.4. LIN KT CNG HA TR

4.1. S hnh thnh lin kt cng ha tr1.1. Lin kt cng ha tr hnh thnh gia cc nguyn t ging nhau* S hnh thnh n chta) S hnh thnh phn t hidro (H2)

1+1+H2H H H H H (Z = 1) : 1s1

b) S hnh thnh phn t nit (N2)NN Vy: Lin kt cng ha tr l lin kt c to nn gia hai nguyn t bng mt hay nhiu cp electron chungNN

2.1. Lin kt cng ha tr hnh thnh gia cc nguyn t khc nhau* S hnh thnh hp chta) S hnh thnh phn t hidro clorua (HCl)H (Z = 1) : 1s1Cl (Z = 17): 1s22s22p33s23p5 H ClClH

b) S hnh thnh phn t kh cacbon ioxit (CO2)C (Z = 6) : 1s12s22p2O (Z = 8): 1s22s22p4C 2 OOC O

4.2.PHNG PHP CNG HA TR VB 1. Nhng tin c bn ca thuyt lin kt cng ha tr VB Mi lin kt cng ha tr c to thnh do s ghp i ca 2e c thn (c spin ngc du nhau) ca hai nguyn t tham gia lin kt. Khi xy ra s xen ph ca AO nguyn t Nh vy iu kin to lin kt l cc nguyn t tham gia lin kt phi c electron c thn trn lp v nguyn t.Lu : Nhm 8, nhm 2, cc nguyn t khng tham gia lin kt cng ha tr v khng c electron c thn.

2. Thuyt VB v s hnh thnh lin kt xen ph ca cc AO: ha tr cng ln th lin kt cng bn.C nhiu loi xen ph: s-s (H2); s-p (HCl); p-p (Cl2)

H2H : HH HHClH :ClH ClCl2Cl : ClCl Cl

3. S lai ha cc obitan nguyn t, s hnh thnh lin kt cng ha tr trong phn t.a. Khi nim v s lai ha obitanKho st s hnh thnh lin kt trong phn t Mtan.

Gii thch: hnh thnh phn t metan, trong nguyn t cacbon c t hp gia obitan 2s v ba obitan 2p.Vy lin kt cng ha tr C-H trong phn t CH4 c hnh thnh do s xen ph gia obitan s ca nguyn t hidro vi obitan lai ha ca nguyn t cacbon.

- L s t hp gia cc obitan ca cng nguyn t, c nng lng gn nhau hnh thnh cc obitan lai ha c hnh dng, kch thc v nng lng nh nhau nhng khc nhau v s phn b trong khng gian.

- C bao nhiu obitan nguyn t tham gia t hp th s to nn by nhiu obitan lai ha.Khi nim v s lai ho:

1. Lai ha sp: l s t hp gia 1 obitan s v 1 obitan p to nn 2 obitan lai ho sp nm trn mt ng thng.2. Lai ha sp2: l s t hp gia 1 obitan s v 2 obitan p to nn 3 obitan lai ho sp2 hng v 3 nh ca tam gic u.3. Lai ha sp3: l s t hp gia 1 obitan s v 3 obitan p to nn 4 obitan lai ho sp3 hng v 4 nh ca t din u.b. Cc kiu lai ha thng gp

V D P DNG: Gii thch s hnh thnh lin kt trong cc phn t sau:BeH2 phn t c cu trc ng thng.BF3 phn t c cu trc tam gic u.CH4 - phn t c cu trc t din u.

BeH2BF3CH4 Nhn xt chung v thuyt lai ho: Thuyt lai ho c vai tr gii thch dng hnh hc phn t sau khi thc nghim xc nh c, hn l tin on dng hnh hc ca phn t.

III.5. LIN KT KIM LOI

nh ngha lin kt kim loi ?

- So snh lin kt kim loi vi lin kt cng ho tr Ging nhauKhc nhau So snh lin kt kim loi vi lin kt ion Ging nhau - Khc nhau - L lin kt c hnh thnh gia cc nguyn t v ion kim loi trong mng tinh th do s tham gia ca cc electron t do.

C cc e chung LKKL: tt c e.

do lc ht tnh in ... LKKL: lc ht gia ion dng k.loi v cc e t do. 5.1. KHI NIM V LIN KT KIM LOI

Mt s kiu mng tinh th kim loi- K tn 3 loi thng gp- Cho v d mi loi- V tr cc nguyn t v ion kim loi - c kht l g ? - So snh ca 3 loi tinh th.

5.2. KIU MNG TINH TH KIM LOI

2.1. Mt s kiu mng tinh th kim loi- Lp phng tm khiVD: IA(Li, Na, K...), Fe- Lp phng tm din VD: Ca, Sr, Al , Cu, Ag, Au, Pb

- Lc phng VD: Be, Mg, Zn,Co

Cc nguyn t, ion nm : nh, tm hnh lp phng

nh, tm cc mt hnh lp phng

nh, tm cc hnh lc gic v ba nguyn t, ion pha trong hnh lc gic. 5.2. MNG TINH TH KIM LOI

c kht l g ?

- So snh ca 3 loi tinh th.

L % th tch m cc nguyn t chim trong tinh th.

- Lp phng tm khi = 68% - Lp phng tm din, lc phng = 74%

5.2. MNG TINH TH KIM LOI

MT S TNH CHT VT L CA KIM LOI1 2 34

IA1H3Li55Cs11Na19K37Rb2He87Fr13456724Be56Ba12Mg20Ca38Sr88Ra27Co45Rh57*La77Ir39Y89**Ac28Ni46Pd72Hf78Pt40Zr29Cu47Ag73Ta79Au41Nb21Sc22Ti23V24Cr42Mo74W25Mn43Tc75Re26Fe44Ru76Os30Zn48Cd80Hg32Ge50Sn82Pb33As51Sb83Bi34Se52Te84Po31Ga49In81Tl35Br53I85At36Kr54Xe86Rn6C14Si7N15P8O16S5B13Al9F17Cl10Ne18Ar62Sm94Pu63Eu95Am64Gd90Th96Cm58Ce59Pr91Pa60Nd92U61Pm93Np65Tb97Bk67Ho99Es68Er100Fm69Tm101Md66Dy98Cf70Yb102No71Lu103LrIIAIIIAIVBVBVIIBIBIIBVIBVIIIBVIIAVAIVAVIAIIIAVIIIA