Question

A solid AB has ZnS type structure. If the radius of cation is 50 pm, calculate the maximum possible value of the radius of anion B⁻ . 

Answer 1

Given: Radius of cation (r⁺ ) = 50 pm

To find: Radius of anion (r⁻ ) = ? 

Formula: Radius ratio =  Radius of the cation/Radius of the anion

Calculation: ZnS has tetrahedral arrangement. 

The range of r⁺/r^- for stable four fold coordination is 0.225 to 0.414

Hence the radius of anion can be calculated by