Q. 1.13 Explain how much portion of an atom located at

            (i) corner and

            (ii) bodycentre of a cubic unit cell is part of its neighbouring unit cell.

Answers (1)

(i) At corner:-    Each atom at a corner is shared between eight adjacent unit cells, four unit cells in the same layer and four unit cells of the upper (or lower) layer. Therefore, only \frac{1}{8}thof an atom (or molecule or ion) actually belongs to a particular unit cell. 

(ii) At body centre of cubic cell:-   Since body centre atom completely belongs to the unit cell in which it is present, thus it is not part of any neighbouring unit cell. So, one atom belongs to a one unit cell.