LIEN KET HOA HOC
3.65. a) Gg ix vay la sd proton trong cdc hat nhdn hay sd electro nd ldp vd
nguyen tft A va B tuang ftng.
Ta ed : X + 3y = 42 - 2 = 40. Nhu vdy y < 40/3 = 13,33. B thudc chu ki 2 va la mdt phi kim (tao anion) nen B chi cd thi la flo, oxi hodc nita.
Khi B la flo thi y = 9, AF3" va A cd sd oxi hoa bdng +1 va x = 40 - 3 x 9 = 13. Trudng hgp nay loai vi nhdm khdng cd sd oxi hod bdng +1.
Khi B la oxi thi x = 16 ta cd A la luu huynh. Trudng hgp nay chap nhdn duge vi cd ion SO3 .
Khi B la nito thi AN3~ va A cd sd oxi hod = + 7 mdu thudn vdi kit qua X = 19 ling vdi kali. Trudng hgp nay loai.
Nhu vdy A cd sd khd'i bdng 32, B cd sd khd'i bdng 16. ' b) Cd'u hinh electron nguyen tft cua hai nguyen td la :
S O : mi Is^ n 11 2s2 m n n i i 2P^ u t t tl 3s2 l i 1 t 3P^ Is^ 2s^ 2p^
3.66. Mac du cd dd dm dien tuong duong nhau nhung trong phdn tft CI2 chi cd lien ket dan (lien kit a) trong khi dd nita tdn tai d dang phdn tft hai nguyen tft vdi lien kdt ba (1 lien kit a va hai lien kit 71) N = N. Ndng lugng cdn dl phd vd lien kit ba trong phdn tft nito ldn ban nhilu so vdi ndng lugng cdn dl phd vd mdt lien kit don trong phdn tft clo. Do vdy d dilu kien thudng nita cd kha ndng phan ftng kem ban clo*
3.67. Tft cd'u hinh electron nguyen tft ciia tittig nguyen td :
9 9 fi 1 9 V
A : Is 2s 2p 3s vdi tdng sd electron bdng 11. Nhu vdy nguyen td A cd sd thft tu la 11, d chu ki 3, nhdm IA va la kim loai kilm.
M : Is^ 2s^ 2p^ 3s^ 3p' vdi tdng sd electron bdng 13. Nguyen td M cd sd thft tu la 13, chu ki 3, nhdm IDA va la kim loai.
X : Is^ 2s^ 2p^ 3s^ 3p^ cd tdng sd electron bdng 17 vdi sd thft tu la 17, chu ki 3, nhdm VIIA va la phi kim.
3.68. Cdc nguyen tft cua cac nguyen td cd xu hudng dat dugc ldp vd electron ciia cdc nguyen tft khi hidm. Ndu chi kl ldp ngoai cung thi cac nguyen tft khf hidm thudng cd 8 electron. Do vdy quy tdc bat tft cd thi dugc coi la quy tdc chung dl xet kha ndng lien kit vdi nhau cua cac nguyen tft.
Thgc td quy tdc bat tft kha dung cho cdc nguydn td chu ki 2. Cd thi ldy trudng hgp quy tdc bat tft dugc thgc hidn dung la cdc phdn tft CH4 hay CO2 hay NH3. Trong cac trudng hgp nay cdc nguydn tft C va N diu cd dft 8 electron d ldp vd.
Cd kha nhilu trudng hgp quy tdc bat tft khdng dugc thuc hidn : Trong phdn tft nito oxit (N = O), N chi ed 7 electron hay trong phdn tft SFg thi S cd tdi 12 electron d ldp electron hod tri sau khi tao lidn kd't.
9 9 fi 9 fi 9
3.69. Cdu hinh electron nguyen tft cua nguyen td X la Is 2s 2p 3s 3p 4s . X la nguydn td canxi vdi 2 electron d ldp vd nen dl dang nhudng di ca 2 electron dl tao ra cation Ca "^.
9 9 fi 9 S
Cdu hinh electron nguyen tft cfta nguydn td Y la Is 2s 2p 3s 3p . Y la nguyen td clo vdi 7 electron d ldp electron ngoai cung ndn dl dang nhdn
1 electron dl tao ra ion clorua (Cl ).
Canxi la mdt kim loai rd't manh vd clo la mdt phi kim rd't manh. Hai nguyen td tren khi kdt hgp se tao ra lien kdt ion gifta kim loai manh vd phi kim manh.
Ca + Cl2 -^ CaCl2
3.70. Ggi x va y ldn lugt la sd mol cfta kim loai kilm A va natri. Ta cd cac phuong trinh phan ftng xay ra :
2A + 2H2O -> 2A0H + H 2 t (a)
X X
2Na + 2H2O -> 2NaOH + H2t (b)
y y
AOH + HCI -^ ACI + H2O (c)
X X
NaOH + HCI -^ NaCl + H2O (d)
y y
Tft cdc phuang trinh phan ftng trdn ta cd tdng sd mol HCI cdn dung dl trung hod AOH va NaOH bdng tdng sd mol natri vd kim loai kilm A. Ta cd hd 2 phuang tnnh :
x + y = 0,2 (1) xA +23y = 3 (2) Hai phuang trinh vdi 3 dn sd nen giai trgc tilp khdng dugc. Ta ed phuang
trinh he qua : x.A + 23 (0,2 - x) = 3. Hay x =^7:7^ > vi x > 0
ta cd : 23 - A > 0 va A < 23. Dua vdo bang tudn hodn ta thd'y nhdm kim loai kilm cd gia tri nguyen tft khdi bdng 7 (Li), 23 (Na), 39 (K), 85,5 (Rb), 133 (Cs). Nhu vdy kim loai A la Li vdi nguydn tft khd'i bdng 7. 116
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