CBSE Class XII Chemistry 2013 Question Papers With Solutions

Number of atoms present in one face-centred cubic crystal:
Number of atoms present at corners per unit cell
= 8 corner atoms ×

1

8

atom per unit cell = 1 atom
Number of atoms present at faces per unit cell = 6 face-centred atoms ×

1

2

atom per unit cell = 3 atoms
∴Total number of atoms per unit cell = 4 atoms.