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.
An atom at the comer is shared by eight adjacent unit cells. Hence, portion of the atom at the comer that belongs to one unit cell=1/8.
An atom at the body centre is not shared by any other unit cell. Hence, it belongs fully io unit cell.
An atom located at the corner of a cubic unit cell is shared by eight adjacent unit cells. Therefore, 1/8 th portion of the atom is shared by one unit cell.
An atom located at the body centre of a cubic unit cell is not shared by its neighbouring unit cell. Therefore, the atom belongs only to the unit cell in which it is present i.e., its contribution to the unit cell is 1.