Question

A compound formed by elements X and Y crystallizes in the cubic structure where Y atoms are at the comers of the cube and X atoms are at alternate faces. What is the formula of the compound?

Answer 1

As there are 8 Y atoms are at the comers of the cube and the contribution of each

= 1/8 therefore no. of Y atoms per unit cell

= 8 × 1/8

= 1

These can only be 2 × atoms an alternate forces.

As contribution of each of them = 1/2.

Therefore number of X atom per unit cell

= 2 × 1/2

= 1

Ratio of atom X : Y = 1 : 1

Hence the formula of the compound is 1 : 1.