Question

The ionic radii of F^– and O^2– respectively are 1.33 Å and 1.4 Å, while the covalent radius of N is 0.74 Å. 

The correct statement for the ionic radius of N^3– from the following is : 

(1) It is smaller than F^– and N 

(2) It is bigger than O^2– and F^– 

(3) It is bigger than F^– and N, but smaller than of O^2– 

(4) It is smaller than O^2– and F^– , but bigger than of N

Answer 1

Answer is (2) It is bigger than O^2– and F^–

F^– , O^2– and N^3– all are isoelectronic species in which N^3– have least number of protons due to which it's size increases as least nuclear attraction is experienced by the outer shell electrons.

Size order N^3- > O^2- > F^-