Question

Give reasons for the following : 

(i) (CH₃)₃ P = O exists but(CH₃)₃ N = O does not. 

(ii) Oxygen has less electron gain enthalpy with negative sign than sulphur. 

(iii) H₃PO₂ is a stronger reducing agent than H₃PO₃.

Answer 1

(i) Because as N can't form 5 covalent bonds as its maximum covalency is three. the octet cannot be extended as it doesn't have d orbital, while p can extend its octet as it has empty d orbital.

(ii) This is due to very small size' of oxygen atom repulsion between electrons is large in relatively small 2p sub-shell.

(iii) In H₃PO₂ there are 2p-H bonds, whereas in H₃PO₃ there is 1 p-H bond.