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HA I CNG Chng 1: Cu to nguyn t v HTTH cc nguyn t ha hc

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CHNG 1: CU TO NGUYN T V H THNG TUN HON CC NGUYN T HA HC

MC TIU Bit cch phn b cc in t trong nguyn t trng thi c bn v vit c cu hnh in t

cng nh xc nh c b cc s lng t. Xc nh c v tr ca nguyn t trong bng HTTH. Suy lun c tnh cht cc nguyn t da vo s bin thin tnh cht trong bng HTTH.

NI DUNG 1. M u

1.1. Thnh phn ca nguyn t 1.2. Quang ph nguyn t 1.3. M hnh nguyn t Bohr

2. Nhng c s ca c hc lng t 2.1. Sng vt cht Louis de Broglie 2.2. H thc bt nh Heisenberg 2.3. Phng trnh sng Schrodinger

3. ngha ca b bn s lng t 3.1. S lng t chnh, n 3.2. S lng t ph, l 3.3. S lng t t, ml 3.4. S lng t spin, ms

4. C hc lng t cho nguyn t nhiu electron 5. S phn b cc electron trong nguyn t trng thi c bn

5.1. Nguyn l ngoi tr Pauli. 5.2. Nguyn l bn vng - Quy tc Kletskopxki 5.3. Quy tc Hund 5.4. Cu hnh electron nguyn t

6. Bng h thng tun hon cc nguyn t ha hc 6.1. Nguyn tc xy dng bng h thng tun hon 6.2. Cu trc ca bng h thng tun hon cc nguyn t ha hc 6.3. S bin thin tun hon mt s tnh cht ca cc nguyn t ha hc

6.3.1. Bn knh 6.3.2. Nng lng ion ha 6.3.3. i lc electron 6.3.4. m in 6.3.5. S oxy ha

c sch HA HC I CNG (Nguyn c Chung) Chng 2: CU TO NGUYN T - NH LUT TUN HAN t trang 32-36, 45-85.

Tham kho


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1. M U (tham kho) 1.1. Thnh phn ca nguyn t

Nguyn t

Ht Khi lng in tch

Kg amu (u, vC ) Coulomb Thang tng i Lp v Electron (e) 9,1094 x 10-31 0,00054858 -1,60217646 x 10-19 -1

Ht nhn Proton (p) 1,6726 x 10-27 1,0073 +1,60217646 x 10-19 +1

Neutron (n) 1,6748 x 10-27 1,0087 0 0 1.1.1. K hiu nguyn t

X: K hiu nguyn t A: S khi nguyn t = s proton + s neutron Z: Bc nguyn t = S hiu nguyn t = s proton = s electron = S th t ca nguyn t trong bng HTTH.

V d: Xc nh s proton, neutron v electron ca cc nguyn t nguyn t sau:

Nguyn t XAZ B115

126C

136C

168O

178O

S lng proton

S lng neutron

S lng electron

1.1.2. Nguyn t ng v

Nhng nguyn t gi l ng v khi chng c cng s proton Z nhng s khi A khc nhau. Ni cch khc, cc nguyn t ng v c s neutron trong nhn khc nhau.

Nguyn t ha hc l tp hp cc nguyn t c cng in tch ht nhn. Nh vy mi nguyn t c th gm nhiu nguyn t ng v vi thnh phn thng rt xc nh.

V d : ng v Khi lng nguyn t Thnh phn (%)

6329Cu 62,93 vklnt 69,09 6529Cu 64,93 vklnt 30,91

Khi lng trung bnh ca nguyn t ng :

0,6909 x 62,93 + 0,3091 x 64,93 = 63,55 vklnt 1.2. Quang ph nguyn t - phng tin nghin cu cu trc lp v electron nguyn t

Vic nghin cu cu trc lp v electron nguyn t da trn c s thc nghim, trong quan trng nht l da trn nghin cu quang ph cc nguyn t ha hc.

Quang ph nguyn t l quang ph vch, ngha l gm t mt s vch ring bit c mu sc nht nh tng ng vi nhng bc sng xc nh, c trng cho mi nguyn t. Quang ph nguyn t hydro:

Quang ph nguyn t kh hydro l n gin nht c ly lm v d. Nguyn tc hot ng ca my quang ph nh sau :


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Kh hydro long khi b phng in s pht ra nh sng gm nhng tia c bc sng khc nhau. nh sng ny khi i qua mn chn S v thu knh C s b s b lng knh phn tch thnh nhng tia thnh phn. Nhng tia ny nh thu knh P hi t li thnh nhng vch khc nhau trn knh nh E tng ng vi nhng bc sng nht nh (S1, S2).

1.3. M hnh nguyn t Bohr 1.3.1. Ba tin ca Bohr

Trong nguyn t, electron quay xung quanh ht nhn khng phi trn nhng qu o bt k m trn nhng qu o trn, ng tm v c bn knh xc nh (gi l qu o dng hay qu o lng t).

Khi chuyn ng trn nhng qu o ny, electron khng thu hay pht nng lng (nng lng ca n c bo tan). Nh vy mi qu o dng tng ng vi mt mc nng lng xc nh.

Khi hp th nng lng, electron chuyn t qu o c mc nng lng thp ln qu o c mc nng lng cao hn. Ngc li, khi chuyn t qu o c mc nng lng cao v qu o nng lng thp n s pht ra nng lng di dng bc x.

1.3.2. Kt qu thu c t tin Bohr

Tnh tan c bn knh qu o bn, tc v nng lng electron khi chuyn ng trn qu o .

Gii thch c bn cht vt l ca quang ph vch hydro v tnh tan c v tr cc vch quang ph.

iu kin nhit bnh thng, a s electron tn ti mc nng lng thp nht (n=1). Khi b kch thch (v d phng in) cc electron hp thu nng lng t bn ngoi v chuyn ln nhng qu o xa ht nhn v c nng lng cao hn. Cc electron khng tn ti lu trng thi kch thch. Khi cc electron chuyn t qu o lng t xa nhn (nng lng E) v qu o gn nhn (Ec) n pht ra bc x vi tn s tha mn: h = E Ec


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M hnh nguyn t ca Bohr ch gii thch c cho nguyn t hoc ion mt electron

nh hydro, khng ng cho nguyn t nhiu electron. 2. NHNG C S CA C HC LNG T (tham kho) 2.1. Sng vt cht Louis de Broglie

Mi ht vt cht bt k c khi lng m, khi chuyn ng vi tc v s to nn sng truyn i vi bc sng Phng trnh th hin bn cht sng - ht ca mt ht vt cht:

h=

mv

Vi h l hng s Planck. Vi trng hp mt vt th c khi lng ln, nh mt ngi ang i xe my, cng th

hin bn cht sng ht, nhng do khi lng ln nn di sng nh, khng th pht hin c tnh cht sng.

Xt trong nguyn t, electron l mt ht vi m chuyn ng quanh ht nhn, v khi lng ca electron rt nh nn n th hin tnh cht sng. V th c th m t chuyn ng ca n bng mt hm sng . 2.2. H thc bt nh Heisenberg

V nguyn tc khng th ng thi xc nh chnh xc c ta v tc ht vi m. h

x v4 m

Vi x: sai s v v tr; v: sai s v tc . Khi ta ca ht c xc nh cng chnh xc (ngha l sai s x cng nh), th tc

chuyn ng ca n c xc nh cng km chnh xc (ngha l sai s v cng ln). i vi nguyn t, quang ph vch cho bit chnh xc nng lng ca electron, tc tc

chnh xc ca n, v th ta khng th bit chnh xc v tr ca n. Vi c hc lng t khng tn ti khi nim qu o chuyn ng c th ca electron. Ngi ta ch c th xc nh kh nng xut hin electron ti mt im vo mt thi im l nhiu hay t, tc l ch c th bit c xc sut tn ti ca electron ti thi im cho.


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2.3. Phng trnh sng Schrodinger

T bn cht sng ca electron v da vo nguyn l bt nh cho thy rng khng th biu din electron bng mt qu o xc nh m ch bit c vng khng gian, trong xc sut tm thy electron l ln nht (90-99%) hay cn gi l orbital nguyn t (AO, m my in t).

Theo c hc lng t, trng thi ca electron trong nguyn t mt im v thi im c c trng bi mt hm sng (x,y,z) cn gi l hm s xc sut.

Theo , 2(x,y,z) biu din xc sut tm thy electron im (x, y, z) v 2(x,y,z)dV biu din xc sut tm thy electron trong khong khng gian nh dV bao quanh im (x, y, z).

V phng din ton hc, hm s sng l nghim ca phng trnh vi phn gi l

phng trnh sng Schrodinger. = E

: ton t Hamilton E : nng lng ton phn ca electron

ngha ca phng trnh: ng vi mt mc nng lng xc nh, electron c mt trng thi xc nh v ngc li.

n gin ha vic gii phng trnh ny ngi ta thng chuyn n v h ta cu, trong ht nhn nguyn t c t ti tm h ta . Nh vy s l hm s ca ba bin s bn knh vector r (khong cch t tm n electron), cc gc v .

Nghim ca phng trnh Schrodinger l tch ca:

= [R(r)] [()] [()] Do electron c 3 s bc t do r, v nn cc hm s R, v phi cha 3 s lng t,

c k hiu n, l v m, trong n v l xc nh hm s bn knh, cn l v m xc nh cc hm s gc.

R(r) = f1(n, l): hm s bn knh. () = f2(l, ml): hm s gc. () = f3(ml): hm s gc.

Kt qu gii phng trnh sng Schrodinger cho thy hm sng ca electron lun lun

cha ba thng s khng c th nguyn v l nhng s nguyn. Nhng thng s ny c gi l


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s lng t v c k hiu n, l, ml. Mi b ba s lng t n, l, ml xc nh mt orbital nguyn t (k hiu AO, atomic orbital) v miu t trng thi ca electron.

Ngoi ra, ngi ta cn thy rng trng thi ca electron trong nguyn t cn c xc nh bi s lng t th t, c trng cho s t quay ca electron xung quanh trc ca mnh v c k hiu ms.

3. NGHA CA B BN S LNG T

Trng thi electron trong nguyn t c c trng bi nhng gi tr nht nh ca cc s lng t (n, l, ml, ms).

3.1. S lng t chnh n v mc nng lng

Nhn gi tr nguyn dng t 1 n S lng t chnh n : 1 2 3 4 5 6 7 Lp lng t : K L M N O P Q ...

Nhng electron c cng gi tr n lp nn mt lp electron. Xc nh trng thi nng lng ca electron: n cng ln th electron c nng lng cng

cao. 2

nZE = - 13,6 (eV)n

vi n = 1, 2, 3,

Lin quan n kch thc orbital nguyn t: n cng ln, kch thc orbital nguyn t cng ln.

3.2. S lng t orbital l v hnh dng orbital Nhn tng cng n gi tr nguyn dng t 0 n (n-1). c trng cho ln ca moment ng lng ca electron. Xc nh hnh dng v tn orbital nguyn t: l : 0 1 2 3 4 5 K hiu phn lp : s p d f g h


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3.3. S lng t t ml v cc orbital nguyn t ( lng t) Nhn tng s (2l + 1) gi tr, t - l n + l. c trng cho s nh hng cc orbital nguyn t trong t trng. Quyt nh s orbital nguyn t ( lng t) c trong mt phn lp.

3.4. S lng t spin, ms c trng cho thuc tnh ring ca electron. C th nhn mt trong 2 gi tr: +1/2 hoc -1/2 (hai gi tr ny thng c biu th bng

hai mi tn c chiu ngc nhau, v ). Mt electron c biu din bng b bn s lng t (n, l, ml, ms)

V d: V sao mi b bn s lng t di y khng th l b 4 s lng t ca mt electron trong mt nguyn t no ?

a) n = 3, l = +3, ml = +1, ms = +1/2 b) n = 3, l = +1, ml = +2, ms = +1/2

c) n = 2, l = +1, ml = -1, ms = 0 d) n = 4, l = +3, ml = -4, ms = -1/2

4. C HC LNG T CHO NGUYN T NHIU ELECTRON

p dng c hc lng t cho nguyn t nhiu electron l vic khng n gin, phng trnh sng Schrodinger ch c gii theo phng php gn ng. Trong nguyn t c nhiu electron, trng thi nng lng electron khng nhng ty thuc vo s lng t chnh n m cn ph thuc vo c s lng t orbital l. Nguyn nhn: do 2 hiu ng: hiu ng chn v hiu ng xm nhp.

lng t


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Trong nguyn t nhiu electron, ngoi tng tc gia electron vi ht nhn cn c tng

tc gia cc electron vi nhau. Tng tc th hai gy nn trong nguyn t nhiu electron 2 hin tng, gi l hiu ng chn v hiu ng xm nhp.

Hiu ng chn: do lc y ca mnh cc electron bn trong to nn mt mn chn gia ht nhn

v electron ang xt, lm yu i lc ht gia ht nhn v cc electron bn ngoi. Ni cch khc, ch mt phn in tch ht nhn c tc dng tht s ln electron . in tch ht nhn tht s cn gi l in tch ht nhn hiu dng, Z*.

Hiu ng xm nhp: cc electron bn ngai trong khang thi gian nht nh no c th xut hin vng gn ht nhn, ngha l c th xm nhp vo gn ht nhn qua cc lp electron bn trong. Hiu ng xm nhp ngc li vi hiu ng chn: n lm tng lc ht ca ht nhn vi electron xm nhp vo gn ht nhn v y electron t b chn hn.

5. S PHN B CC ELECTRON TRONG NGUYN T TRNG THI C BN

S phn b cc electron trong phn t trng thi c bn c th hin bng cu hnh electron ca nguyn t. S phn b ny tun theo cc nguyn l v nguyn tc sau y. 5.1. Nguyn l ngai tr Pauli

Trong mt nguyn t khng th c hai hoc nhiu electron c 4 s lng t nh nhau. Mt orbital (hay lng t) cha ti a 2 electron, vy 2 electron phi c spin tri chiu.


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5.2. Nguyn l vng bn - Quy tc Kletskopxki trng thi c bn, trong nguyn t, cc electron chan nhng mc nng lng thp

trc (tc l trng thi bn vng trc) ri mi n nhng trng thi c mc nng lng cao hn tip theo.

Theo d kin quang ph, th t tng dn cc mc nng lng AO trong nguyn t trung ha in:

1s < 2s < 2p < 3s < 3p < 4s < 3d < 4p < 5s < 4d < 5p < 6s < 4f 5d < 6p < 7s < 5f 6d < 7p

Trnh t phn b ny c tm tt bng quy tc Kletskopxki:

Quy tc Kletskopxki Khi in tch ht nhn tng, cc electron s chan cc mc nng lng c tng s (n+l) ln

dn. i vi cc phn lp c tng s (n+l) bng nhau th electron c in vo phn lp c tr

s n nh trc ri n phn lp c n ln hn. S :

5.3. Quy tc Hund

Trong mt phn lp, cc electron c sp xp sao cho tng s spin l cc i (ngha l c mt s ti a electron c thn).

Vi cch biu din cu hnh electron bng lng t, cc electron c thn c biu din bng cc mi tn cng chiu, thng hng ln trn. 5.4. Cu hnh electron nguyn t

C hai cch biu din cu hnh electron: Tp hp cc k hiu trng thi lng t c sp xp theo trt t tng dn gi tr s

lng t chnh n v s lng t ph l, ng thi ghi km theo s electron xp vo trng thi di dng s m.

K hiu lng t: mi vung tng ng vi mt orbital nguyn t v electron c biu din bng mi tn.

Cch vit cu hnh electron nguyn t theo cc bc sau:

Xc nh s electron ca nguyn t. Phn b electron theo mc nng lng AO tng dn, theo cc quy tc v nguyn l. Vit cu hnh electron theo th t cc phn lp trong mt lp v theo th t ca cc lp

electron.

1s 2s 2p 3s 3p 3d 4s 4p 4d 4f 5s 5p 5d 5f 6s 6p 6d 6f 7s 7p 7d 7f

n+l 7 6 5 4 3 2 1


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V d: Biu din cu hnh electron ca nguyn t Sc (Z=21)

S electron ca Sc l 21. Phn b electron theo mc nng lng: 1s22s22p63s23p64s23d1

Vit cu hnh sp xp cc phn lp theo tng lp: 1s2 2s22p6 3s23p63d1 4s2 hay vit gn l [Ar] 3d14s2

Lu mt s ngoi l bn cu hnh electron th hin : lp electron bo ha : l 2 khi n=1, l 8 khi n=2, l 18 khi n=4, l 32 khi n=4 phn lp bo ha s2, p6, d10, f14 V d: p6 phn lp bn bo ha p3, d5, f7 V d: p3

V d:

Cr (Z=24) s electron l 24: 1s22s22p63s23p63d44s2 hay vit gn hn [Ar] 3d44s2

nhng li c cu hnh [Ar] 3d54s1 v thng thng cc nguyn t tr nn bn hn khi cc orbital cng mc nng lng cha ti a s electron (bo ha hoc bn bo ha). Phn bit: electron cht cng (in cui cng vo cu hnh) electron lp ngai cng

V d:

Sc (Z=21) s electron l 21: 1s22s22p63s23p63d14s2 hay vit gn l [Ar] 3d14s2

Electron cht cng (in cui cng) trn 3d1. Electron ngoi cng trn 4s2.

S tch / thm electron to ion: To cation: tch electron t lp ngoi cng trc. To anion: thm electron nh quy tc.

V d: a) Cr (Z=24) s electron l 24: 1s22s22p63s23p63d44s2 hay vit gn l [Ar] 3d44s2

Cr3+ mt 3 electron t lp ngoi cng trc nn c cu hnh l [Ar] 3d3

2s 2p 1s

3s 3p 4s 3d

2s 2p 1s

3s 3p 4s 3d


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b) O (Z=8) s elctron l 8: 1s22s22p4 hay vit gn l [He] 2s22p4

O2- thm 2 electron theo th t mc nng lng v theo cc quy tc nn c cu hnh l [He] 2s22p6 V d: Xc nh b 4 s lng t ca electron in cht cng trong nguyn t N (Z=7) V d: Bit electron in cht cng trong nguyn t X c biu din bng b 4 s lng t (2,1,0,-1/2). Hy xc nh cu hnh electron ca nguyn t X. V d: Vit cu hnh electron ca nguyn t V (Z=23) v ion V3+ . Xc nh b 4 s lng t ca electron in cht cng trong nguyn t V.


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6. BNG H THNG TUN HAN CC NGUYN T HA HC

6.1. Nguyn tc xy dng bng h thng tun han

Pht biu nh lut tun hon: Tnh cht ca cc nguyn t ph thuc tun han vo in tch ht nhn nguyn t ca nguyn t.

Nguyn tc xy dng bng: Cc nguyn t c sp xp theo chiu tng dn ca in tch ht nhn. Dy cc nguyn t thuc cng mt chu k c xp thnh mt hay nhiu hng ngang. Nhng nguyn t c cu trc lp v electron ngoi cng ging nhau c xp chung vo

mt ct gi l nhm. 6.2. Cu trc ca bng h thng tun han cc nguyn t ha hc

H thng tun han ngy nay gm 118 nguyn t, vi 7 hng (chu k) v 18 ct (nhm) [8 nhm A v 8 nhm B (ring nhm VIIIB chim 3 ct) (dng bng di). 6.2.1. Chu k

Chu k l mt dy nguyn t sp xp theo s th t tng dn m nguyn t ca chng c cng s lp. Mi chu k m u l kim loi in hnh, cui cng l phi kim in hnh, kt thc l kh him.

c bit, cc nguyn t f thuc chu k 6 v chu k 7 c xp vo hai h, v c tnh cht ging nhau: Chu k 6 vi h Lantanid. Chu k 7 vi h Actinit.

6.2.2. Nhm Nhm bao gm cc nguyn t c cng s electron ha tr cu hnh electron tng t

nhau tnh cht ha hc tng t nhau. Nhm A: gm cc nguyn t s v p. Nhm B: gm cc nguyn t d, u l kim lai chuyn tip. Ring Zn, Cd v Hg c phn

lp d bo ha nn khng c coi l kim loi chuyn tip cng nh nguyn t in hnh.

Ch thch: - Nguyn t s, p, d, f l nguyn t tng ng trong phn lp s, p, d, f ang c xy dng. - Electron ha tr: L nhng electron lp ngoi cng (n ln nht) v phn lp cn ngoi cng (d hoc f)

cha bo ha, C nng lng cao nht v xa ht nhn nht, Xc nh tnh cht ha hc ca nguyn t. C kh nng to lin kt ha hc.


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V d: C (Z=6): 1s22s22p2 s electron ha tr l 4. V (Z=23): 1s22s22p63s23p64s23d3 s electron ha tr l 5. Zn (Z=30): 1s22s22p63s23p64s23d10 s electron ha tr l 2. (khng tnh 10e trn phn lp

3d do phn lp ny bo ha). 6.2.3. S lin h gia c cu electron v bng HTTH

S th t ca chu k c xc nh t s lp electron. S th t ca nhm c xc nh t s electron ha tr.

Electron ha tr thuc phn lp s, p nhm A: s th t nhm = tng s electron lp ngoi cng

Electron ha tr thuc phn lp d nhm B: Cc electron trn phn lp d cha bo ha cng c kh nng to thnh lin kt ha hc nn

cng c coi l electron ha tr. S electron ha tr trong trng hp nhm B c tnh bng tng s electron thuc lp ngoi cng v phn lp cn ngoi cng cha bo ha.

(n-1)dx ns2 vi x 16, s th t nhm = (2+x)B (n-1)d6ns2, (n-1)d7ns2 v (n-1)d8ns2 cng thuc nhm VIIIB (n-1)d9ns2 (n-1)d10ns1 nhm IB (n-1)d10 ns2 nhm IIB.

6.2.4. Xc nh tnh cht kim lai v phi kim Thc ra, khng c ranh gii r rt gia tnh kim lai v phi kim. Mt cch tng i, trong

bng HTTH, cc nguyn t kim lai v phi kim c phn cch bng ng cho bc thang, bn tri l kim lai, bn phi l phi kim. in hnh, cc nguyn t cc nhm IA, IIA, IIIA (tr hidro v bo) c tnh kim lai. Cc nguyn t nhm VA, VIA, VIIA c tnh phi kim (tr antimon, bismut v poloni). Cc nguyn t ngay cnh ng cho c tnh cht trung gian gia kim loi v phi kim.

Bi tp : Vit cu hnh electron nguyn t ca cc nguyn t sau :

a) X thuc chu k 4, nhm IIA b) Y thuc chu k 4, nhm IIB c) Z thuc chu k 5, nhm IB d) T thuc chu k 6, nhm IVA


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Bi tp: a) Xc nh nguyn t X, bit X cng chu k vi Ag (Z=47) v cng nhm vi Ge (Z=32) b) Xc nh nguyn t Y, bit Y thuc chu k 4 v cng nhm vi Si (Z=14)

Bi tp: Cation R+ c cu hnh electron 1s22s22p63s23p6. Trong h thng tun han, nguyn t R thuc chu k v phn nhm no ? Bi tp: Anion R- c cu hnh electron 1s22s22p63s23p6. Trong h thng tun han, nguyn t R thuc chu k v phn nhm no ?

6.3. S bin i tun han mt s tnh cht ca cc nguyn t ha hc 6.3.1. Bn knh 6.3.1.1. Khi nim

Do cc orbital nguyn t khng c gii hn r nt nn khng th xc nh c bn knh nguyn t v ion mt cch chnh xc. Do , ngi ta xc nh i lng ny da trn khong cch gia cc ht nhn nguyn t to nn n cht hay hp cht tng ng (gi l bn knh hiu dng), y ch l i lng quy c.

Bn knh kim loi bng khong cch gia cc ht nhn nguyn t trong tinh th. Bn knh cng ha tr bng khong cch gia cc ht nhn nguyn t trong tinh th

hay phn t n cht. i vi hp cht ion khong cch gia hai ht nhn c xem l tng bn knh ca 2 ion

dng v ion m. 6.3.1.2. Cc yu t nh hng n bn knh nguyn t

S lp electron : n cng ln kch thc orbital cng ln bn knh nguyn t cng ln.

in tch ht nhn hiu dng: Z* cng ln lc ht ca ht nhn i vi cc electron cng mnh m my in t b co li bn knh nguyn t gim.

6.3.1.3. Bin thin bn knh nguyn t Theo chu k, t tri sang phi, in tch

ht nhn tng, bn knh nguyn t c khuynh hng gim dn. V : s lp electron ging nhau, nn hiu ng chn ca electron lp bn trong l nh nhau, in tch ht nhn hiu dng tng nn lc ht electron lp ngai cng cng mnh, bn knh nguyn t gim.

S gim ny r rng i vi cc nguyn t s, p nhng li khng r rng vi nhng chu k ln. Do nhng chu k ln, a s nguyn t c electron sp xp vo cc orbital (n-1)d hoc


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(n-1)f k ngoi cng, nhng electron ny c tc dng che chn mnh ht nhn i vi lp electron ngoi cng ns, lm cho lc ht gia cc ht nhn vi cc electron ngoi cng ns ny thay i khng r rng, dn ti s gim khng u n bn knh nguyn t khi i t u n cui chu k, l s co d hay co f.

Theo nhm, t trn xung di, s tng s lp electron din ra nhanh hn s tng in tch ht nhn nn bn knh nguyn t tng.

i vi nguyn t nhm A, t trn xung di bn knh nguyn t c khuynh hng tng dn. L do s lp electron tng v hiu ng chn chim u th so vi s tng in tch ht nhn lm cho lc ht gia ht nhn vi cc electron ngoi cng gim xung. Do vy, bn knh nguyn t tng dn.

i vi nguyn t nhm B, t trn xung di, t nguyn t chu k 4 n chu k 5, bn knh c tng ln. T chu k 5 n chu k 6, bn knh t thay i (khng i hoc gim cht t). L do: s co rt lantan ca nguyn t f.

6.3.1.4. Bin thin bn knh ion

Khi mt nguyn t trung ha nhn electron chuyn thnh mt anion, bn knh ca n tng. Khi mt nguyn t trung ha nhng electron chuyn thnh mt ion dng, bn knh ca

n gim.

Ion ng electron (c cng s electron lp v): ion no c in tch ht nhn Z ln hn s

c bn knh nh hn. i vi cc cation v anion ng electron th cation c bn knh nh hn anion.

V d:

Na+ (Z=11, 10 electron) c cu hnh electron: 1s22s22p6. F- (Z=9, 10 electron) c cu hnh electron: 1s22s22p6. Ht nhn nguyn t Na (Z=11) c nhiu in tch ht nhn hn so vi F (Z=9) bn knh ion

Na+ nh hn bn knh F-.

Al3+ Mg2+ Na+ Ne F- O2- N3-Al3+ Mg2+ Na+ Ne F- O2- N3-

CCng 10 electronng 10 electron


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Bi tp: Sp xp cc nguyn t v ion sau y theo bn knh tng dn : a) Ca (Z=20), Al (Z=13), P (Z=15), K (Z=19) b) Cl (Z=17), Al (Z=13) , P (Z=15) , Na (Z=11) , Ar (Z=18) c) Na+ (Z=11) , Ne (Z=10) d) Mg2+ (Z=12) , F- (Z=9) , Na+ (Z=11) , O2- (Z=8) , Al3+ (Z=13)

e) Be (Z=4), Mg (Z=12), Ba (Z=56) 6.3.2. Nng lng ion ha (I) 6.3.2.1. Khi nim

Nng lng ion ha l nng lng ti thiu cn thit tch hon ton mt electron ra khi nguyn t trng thi c bn v trng thi kh. c trng cho kh nng nhng electron ca nguyn t, th hin tnh kim loi. I cng nh nguyn t cng d nhng electron, do tnh kim loi v tnh kh ca nguyn t cng mnh.

M(k) + I1 M+(k) + 1e (I1 > 0) Nng lng ion ha th 2 (I2), th 3 (I3), th 4 (I4), l nng lng cn bt electron

th 2, th 3, th 4 ra khi ion dng c in tch +1, +2, +3, lun lun c I1 < I2 < I3 < < In. Nng lng ion ha lun lun mang du dng. Nng lng ion ha cng ln cng kh

tch electron ra khi nguyn t. 6.3.2.2. Cc yu t nh hng

in tch ht nhn Z ln gi electron cng cht I ln Bn knh nguyn t nh gi electron cng cht I ln. Cu hnh electron bo ha nguyn t cng bn I ln.

6.3.2.3. S bin thin nng lng ion ha trong bng HTTH Theo chu k, t tri sang phi ni chung Z tng, I1 tng.

Cu hnh bo ha 1s2 v ns2np6 (kh him) l bn vng nht nn c nng lng ion ha rt ln, cu hnh bn bo ha p3 tng i bn vng c nng lng ion ha kh ln.

Cc nguyn t chuyn tip c nng lng ion ha t thay i. Theo nhm:

Trong cc nguyn t nhm A, t trn xung, n tng, bn knh tng mnh, ng thi hiu ng chn ca cc lp electron bn trong cng tng ln, tt c nhng iu ny lm gim lc ht gia ht nhn vi cc electron bn ngoi I1 gim (tnh kim loi tng).

Trong cc nguyn t nhm B, vic tng in tch ht nhn v hiu ng xm nhp ca cc electron s lp ngoi cng lm ht nhn gi electron ngoi cng cht hn I1 tng (tnh kim loi gim).


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Bi tp: Sp xp cc tiu phn sau theo nng lng ion ha tng dn : a) O2-(Z=8), F-(Z=9), Na+(Z=11), Mg2+(Z=12)

b) K+ (Z=19), Ar (Z=18), Cl- (Z=17) Bi tp: Gii thch cc gi tr nng lng ion ha (I1, kJ/mol) ca cc nguyn t sau : a) Na (Z=11, I1=496), Mg (Z=12 , I1=738), Al (Z=13 , I1=578) b) C (Z=6 , I1=1086), N (Z=7 , I1=1400), O (Z=8, I1=1314) 6.3.3. i lc electron (E) 6.3.3.1. Khi nim

i lc electron l nng lng ta ra (mang du m, -) hay hp th (mang du dng, +) khi c mt electron kt hp vo mt nguyn t t do trng thi kh cho mt ion m. c trng cho kh nng nhn electron ca nguyn t, th hin tnh phi kim. E cng m nguyn t cng d nhn electron, do tnh phi kim loi v tnh oxy ha ca nguyn t cng mnh.

X(k) + 1e X-(k) + E Quy c v du ca E:

E0) Ne(k) + e Ne(k) E = 40 kJ/mol

E cng m cng d nhn electron, tnh phi kim v tnh oxy ha ca n cng mnh. Phn ln cc nguyn t ha hc c E0 do t cu hnh electron

bo ha phn lp hoc lp nn khng nhn thm electron. Mg (Z=12) 1s22s22p63s2 Zn (Z=30) 1s22s22p63s23p64s23d10 Ar (Z=18) 1s22s22p63s23p6

6.3.3.2. Cc yu t nh hng in tch ht nhn Z ln D nhn electron E cng m Bn knh nguyn t nh D nhn electron E cng m Cu hnh electron bo ha nguyn t cng bn, kh nhn thm e E cng dng.

6.3.3.3. Bin thin i lc electron Trong chu k, t tri sang phi theo chiu tng in tch ht nhn E cng m (tr kh

him). Trong phn nhm chnh, t trn xung do s tng bn knh nn electron mi thm vo

t c nhn gi cht nn E cng dng, nhng s thay i khng ng k do nh hng bi hai yu t tri chiu nhau (in tch ht nhn tng d nhn e v bn knh nguyn t tng kh nhn e). Ring nhm 2A, 5A v 8A c s thay i bt thng, do cc nguyn t ny c phn lp ngoi cng bo ha hoc bn bo ha, vic thm electron cc nhm ny kh khn hn.


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Cc phi kim c E m hn kim lai. Cc halogen c E m hn cc nguyn t khc, v nhm ny d thu thm electron. Cc nguyn t kh him lun c E>0 v lp electron ngai cng vi cu hnh bo ha s2p6

kh thu thm electron. Trong thc t, vic xc nh bng thc nghim i vi i lc electron kh khn hn vic xc nh nng lng ion ha v ch yu thc hin bng phng php gin tip.

6.3.4. m in 6.3.4.1. Khi nim

Theo Pauling, m in ca mt nguyn t trong phn t l kh nng ca nguyn t ny ht m my electron v pha mnh khi to lin kt vi nguyn t khc. Lc ht cng mnh th m in cng ln. Flor l nguyn t phi kim mnh nht nn c m in ln nht (3.98). Da vo Pauling tnh c m in ca tt c cc nguyn t cn li trong bng HTTH.

Nguyn t c m in ln c khuynh hng ht in t th hin tnh cht phi kim. Nguyn t c m in nh c khuynh hng y in t th hin tnh cht kim loi. 6.3.4.2. Bin thin m in trong bng HTTH

m in lin quan n nng lng ion ha v i lc electron. Nng lng ion ha cng nh (cng d nhng in t th hin tnh kim loi) th m in cng nh. i lc electron cng m (cng d nhn in t th hin tnh phi kim) m in cng ln.

Theo phn nhm chnh t trn xung, m in c khuynh hng gim t trn xung di.

Theo chu k, m in c khuynh hng tng dn t tri sang phi. Flor c m in ln nht (3.98), tip l oxy:

F > O > Cl > N > S > C > P > B > Si


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6.3.5. S oxy ha 6.3.5.1. Khi nim

S oxy ha ca nguyn t bng s electron m nguyn t nhng (s oxy ha dng) hay nhn (s oxy ha m) to thnh ion c cu hnh bo ha ns2np6 hay ns2np6(n-1)d10. 6.3.5.2. Cch xc nh s oxy ha

S oxy ha dng cao nht ca mt nguyn t bng s electron ha tr ca n = s nhm (ngoi tr cc nguyn t O, F, IB v VIIIB).

S oxy ha m thp nht (nu c) = s nhm 8. Cc nguyn t kim loi chuyn tip thng c s oxy ha thp nht +2 v cao nht ng vi

s nhm; ngoi ra nhiu trng hp biu l s oxy ha bt thng : Oxy c cc s oxy ha -2, -1, 0 v +2, s oxy ha dng cao nht +2. (H2O, H2O2, O2,

OF2) Flo c cc s oxy ha -1 v 0, s oxy ha m -1.(HF, F2) Nhm IB c s oxy ha cao nht ln hn s nhm. VD : Cu +1 v +2, Au +1 v +3.

(CuCl, CuCl2, AuCl, Au(OH)3) Nhm VIIIB c s oxy ha dng cao nht nh hn s nhm, s oxy ha ca chng

khng qu +6. Ring Ru v Os c s oxy ha dng cao nht +8. Lu : Kim lai ch c s oxy ha dng, khng c s oxy ha m v lun c tnh kh.

TNG KT S THAY I TNH CHT CA CC NGUYN T TRONG BNG HTTH

Atomic radius : Bn knh nguyn t. Electron affinity : i lc electron Ionization energy : Nng lng ion ha Metallic character : Tnh kim loi Nonmetallic character : Tnh khng kim loi

BI TP 1.Nguyn t X , Y c electron cui biu din bng 4 s lng t :

X : n = 4 , l =0 , ml = 0 , ms = +1/2 Y : n = 3 , l =1 , ml = 0 , ms = -1/2 Z l nguyn t thuc chu k 4, nhm VIIB

a) Vit cu hnh electron ca X , Y, Z. Xc nh v tr X, Y trong bng HTTH. b) Xc nh s oxi ha m thp nht v dng cao nht ca X, Y, Z. 2.Cho cc nguyn t ca nguyn t A, B, C, D c electron cht cng c biu din bng 4 s

lng t nh sau : A : n = 3 , l =1 , ml = -1 , ms = -1/2 B : n = 3 , l =1 , ml = +1 , ms = +1/2 C : n = 3 , l =2 , ml = 0 , ms = +1/2 D : n = 4 , l =1 , ml = +1 , ms = +1/2


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a) Xc nh v tr cc nguyn t trong bng HTTH. b) So snh nng lng ion ha th nht I1 ca A, B. Gii thch ? c) Xc nh s oxi ha m thp nht v dng cao nht ca A, B.

3.Nguyn t X thuc chu k 4, s oxi ha m thp nht l -3 Nguyn t Y thuc chu k 2, s oxi ha m thp nht l -2. Vit cu hnh electron ca X, Y.

4. Cho nguyn t A chu k 2, nguyn t B chu k 3, nguyn t C chu k 4. A, B, C u to vi hydro hp cht c cng thc H2X (X = A, B, C), trong A, B, C th hin s oxi ha m thp nht.

a) Vit cu hnh electron ca A, B, C. b) Xc nh 4 s lng t ca in t cui cng ca A, B, C.

5. Vit cu hnh electron ca cc nguyn t A, B, C, D, E , F v xc nh : a) in tch ht nhn Z, chu k, phn nhm trong bng HTTH b) L kim loi hay phi kim, s oxi ha m thp nht (nu c) v s oxi ha dng cao nht.

Bit rng cc nguyn t A, B, C vi cc ion tng ng A2-, B-, C+ c cu hnh electron ca nguyn t kh tr Ne (Z=10), cc nguyn t D, E, F vi vi cc ion tng ng D2-, E- v F+ c lp v ngoi cng l 3p6.

6. C ba orbital nguyn t : 1) n=5, l=2 2) n=4, l=3 3) n=3, l=0

Hy xc nh tn ca ba orbital nguyn t trn. 7. Electron cht cng in vo cu hnh ca nguyn t R c b 4 s lng t: n = 3, l = 2, ml = -2, ms = -1/2 Hy xc nh s th t Z ca nguyn t R 8. Mt nguyn t c s th t Z=24. Hy xc nh b 4 s lng t ca electron lp ngai cng. 9. Hy xc nh s electron c thn ca nguyn t Fe (Z=26). 10.Hy xc nh s electron c thn ca nguyn t Cr (Z=24). 11. Trong h thng tun han, nguyn t vng thuc chu k 6, nhm IB. Hy xc nh electron

ha tr ca ion Au3+ nm trn phn lp no ? 12. Electron ha tr ca lu hynh (Z=16) l nhng electron thuc cc lp v phn lp no ? 13. Cation R+ c cu hnh electron 1s22s22p63s23p6. Trong bng h thng tun han, nguyn t R

thuc chu k v phn nhm no ? 14. Anion R- c cu hnh electron 1s22s22p63s23p6. Trong bng h thng tun han, nguyn t R

thuc chu k v phn nhm no ? 15. Nguyn t R c cu hnh electron phn lp cht cng l 4p3. Trong bng h thng tun han,

nguyn t R thuc chu k v phn nhm no ?

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