Question

Which of the following species are linear?

• A. ${{ICl}_2}^{-}$
• B. ${I_3}^{-}$
• C. ${N_3}^{-}$
• D. $Cl{O}_2$

Answer 1

Answer: (A), (B), (C)

The correct options are
A ${{ICl}_2}^{-}$
B ${I_3}^{-}$
C ${N_3}^{-}$

(i) $I{Cl}_2^{-2}$

Total valence electrons around I = 7+2+1

= 10 $e^{-}$ = 5 pairs

No. of bond pairs = 2

No. of lone pairs = 3

$\therefore$ It's linear in shape.

(ii) $I_3^{-}$

Total valence electrons around central I = 7+2+1= = 10 $e^{-}$ = 5 pairs

No. of bond pairs = 2

No. of lone pairs = 3

$\therefore$ It's linear in shape.

In the above case, the side I atoms can only act as monovalent because other high oxidation states would be possible only if it denotes an $e^{-}$ pair which is not possible here since the central I does not have empty orbital. the same thing cannot be done for $N_3^{-}$

(iii) $N_3^{-}$

Total valance electrons = 16

Resonating structures of ${IN}_3^{-}$

In all the structures, the central N is sp hybridized

$\therefore$ $N_3^{-}$ resonance hybrid is linear in shape.

(iv) $Cl{O}_2$

Total valence electrons around central I = 7+4= 11 $e^{-}$ = 5 pairs + 1 $e^{-}$

There are two double bonds.

Revised TVEP = 3 pairs + 1 $e^{-}$

$\therefore$ $Cl{O}_2$ is not linear as it contain 2 bond pairs 1 lone pair & 1 odd $e^{-}$ . It is bent in shape