Explain how much portion of an atom located at (i) corner and (ii) body-centre of a cubic unit cell is part of its neighbouring unit cell.

Explanation

a. An atom at the corner is shared by eight adjecent unit cells. Hence, the portion of the atom at the corner that belongs to one unit cell `= (1)/(8)`.
b. The atom at the body centre of a cubic unit of a cubic unit cell is not shared by any other unit cell. Hence, it belongs fully to the unit cell.