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

Explanation

(i) Each corner atom of a cubic unit cell is equally shared by eight adjoining cubic unit cells. Hence, one-eighth of each corner atom belongs to a particular cubic unit cell.
(ii) The body-centred atom of a cubic unit is not shared by other unit cells. Since it is fully within the cell, its contribution to a particular unit cell is 1.