Question

Calculate the number of atoms in a cubic unit cell having one atom on each corner and two atoms on each body diagonal.

Answer 1

8 corner × 1/8 atom per unit cell = 1 atom

 There are four body diagonals in a cubic unit cell and each has two body centre atoms.

 So, 4 × 2 = 8 atoms therefore, total number of atoms per unit cell = 1 + 8 = 9.