Calculate the number of atoms per unit cell in primitive, body centred and face centred cubi unit cells.

Calculate the number of atoms per unit cell in primitive, body centred

1.	Calculate the number of atoms per unit cell in primitive, body centred and face centred cubi unit cells.
Answer» Solution : Primitive UNIT cell : In primitive unit cell, th atoms are located only at a corners Since each cubic unit cell has atoms on it corners, the TOTAL number of atoms per unit ce 1 is `(8 xx 1/8) = 1` atom. Body-centred unit cell : A body-centred cubi unit cell has eight atoms located at corners a cube and ONE atom at the body centred. Hence the number of atoms per unit cell is : `underset("Corner atoms)")underset(darr)(8 xx 1/8) + underset("(Body-centred atom)")underset(darr)(1) + 2` Face-centred unit cell : A face-centred cubi unit cell has eight atoms located at the corner of a cube and SIX atoms located at the centre o each face. Hence, the number of atoms per uni cell is : `underset("(Corner atoms)")underset(darr)(8 xx 1/8) + underset("(Face atoms)")underset(darr)(6xx 1/2) = 4`