Question

What is meant by the term 'coordination number ?

What is the coordination number of atoms

(a) in a cubic close - packed structure ?

(b) in a body - centred cubic structure ?

Answer 1

(i) Coordination number It is defined as the number of nearest neighbours of a particle in a close packed structure.

(a) 12 (as each atom is attached with 12 other atoms.)

(b) 8 (because each atom is attached with 8 other atoms.)