What is the co-ordination number of an atom in each of the following types of cubic lattices ?
(a) Primitive (b) Body centred.

Explanation

(a) In Primitive cubic lattice, each atom is in direct contact with six other atoms. So the co-ordination number of primitive cubic lattice is 6.
(b) In body centred cubic lattice, each atom is in direct contact with eight other atoms, So the co-ordination number of body centred cubic lattice is 8.