Question

An element A and B consitude bcc type crystalline structure. Element A occupies body centre position and B is at the corners
of cube. What is the formula of the compound? What are the coordination numbers of A and B?

Answer 1

Explanation:

Element A is on the center of the body of the crystal and B at the corners.

Total number of atoms in body centered cubic crystalline structure is 2.

Number of Atoms of element A in the crystal = 1

Coordination number of atom A  = 8

Each atom present on the corner is shared by 8 cubic cells.

total corners in one cubic cell = 8

Number of atoms B in the crystal = $8\times \frac{1}{8}=1$

Coordination number of atom B  = 8

The formula of the compound is AB.

Answer 2

Answer:

Given: Crystalline structure is bcc type.

Atoms A are at 8 corners and atom B is at body centre.

.'. Number of atoms of A in a unit cel

1/8 x8=1.

Number of atom B in a unit cell = 1. Since unit cell contains one atom each of A and B, the formula of the compound is AB.

The coordination number of an atom A at corner is 8.

The coordination number of an atom B at body centre is 8.

Ans. Formula of the compound = AB.

Coordination number of A = 8

Coordination number of B = 8.