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K H A I Q U A T VE NHOM HALOGEN 5.1. a) Flo, d 9, chu ki 2, nhdm VIIA ;
b) Clo, d 17, chu ki 3, nhdm VIIA ; c) Brom, d 35, chu ki 4, nhdm VIIA ; d) lot, d 53, chu ki 5, nhdm VIIA.
5.2. Gidng nhau :
- Diu cd 7 electron d ldp ngodi cung (ns^np^) ;
- O trang thdi ca ban, nguydn tft cac halogen diu cd 1 electron ddc thdn.
Khdc nhau :
- Sd ldp electron trong nguyen tft tang ddn tft flo qua clo ddn brom va iot, vi vdy ldp electron ngodi cung xa ddn hat nhdn. (Ldp ngoai cung cua F la ldp thft 2, eua Cl la ldp thft 3, eua Br la ldp thft 4 vd cua I Id ldp thft 5.) - Ldp ngodi cung eua F (Id ldp thft 2) khdng cd phdn ldp d, cdn ldp ngoai cung cua Cl, Br, I diu ed phdn ldp d cdn trdng (khi nguyen tft d trang thai
CO b a n ) .
5.3. F" : [He] 2s^2p* gidng cd'u hinh electron nguydn tft Ne ; c r : [Ne] 3s^3p* gidng cd'u hinh electron nguydn tft Ar; Br~ : [Ar] 3d"'4sHp* gid'ng cd'u hinh electron nguyen tft Kr; r : [Kr] 4d"'5s^5p* gid'ng cd'u hinh electron nguydn tft Xe.
Nhdn xet: Khi nguyen tft halogen X thu them mdt electron thi biln thanh
anion X~ cd cd'u hinh electron trung vdi cd'u hinh electron cua khf hidm dftng ben canh halogen dd trong bang tudn hodn.
5.4. Trong cac halogen rdn vd long, eac phdn tft X2 lien kdt vdi nhau bdng luc Van-dec-Van. Luc nay tdng len theo ehilu tdng cua khdi lugng phdn tft halogen. Vi thd tft flo ddn iot, nhidt dd ndng chdy vd nhiet dd sdi tang ddn. 122
5.5. Trong mdt hgp chd't cd hai nguyen td, nguyen td nao cd do dm dien ldn ban se cd sd oxi boa dm. Ddi vdi cae nguyen td halogen, dd dm dien giam ban se cd sd oxi boa dm. Ddi vdi cae nguyen td halogen, dd dm dien giam ddn nhu sau : F > Cl > Br > I.
Sd oxi hod dm cua eac halogen diu la - 1 . Tdng sd sd oxi hod cua cdc nguyen tft trong mdt phdn tft bdng 0. Dga tren co sd dd, cd thi xac dinh sd oxi boa nhu sau :
a) Trong CIF, sd oxi hod cua clo la +1, cfta flo la - 1 ; b) Trong BrF, sd oxi boa cua brom la +1, cua flo la - 1 ; b) Trong BrF, sd oxi boa cua brom la +1, cua flo la - 1 ; c) Trong BrCl, sd oxi hod cua brom la +1, cua clo la - 1 ; d) Trong ICI, sd oxi hod cua iot la +1, cua clo la - 1 ; d) Trong IBr, sd oxi hod cua iot la +1, cfta brom la - 1 ; e) Trong CIF3, sd oxi hod cua clo la +3, cua flo la - 1 ; f) Trong BrF3 , sd oxi hod cua brom la +3, cua flo la - 1 ; g) Trong ICI3 , sd oxi boa cua iot la +3, cua clo la - 1 ; h) Trong BrF5 , sd oxi hod cua brom la +5, cua flo la - 1 ; i) Trong IF5 , sd oxi hod cua iot la +5, ciia flo la - 1 ; k) Trong IF7, sd oxi boa cua iot la +7, cua flo la - 1 . 5.6. Mg + X2 ^ M g X 2