In a compound, nitrogen atoms (N) make cubic close packed lattice and metal atoms (M) occupy one-third of the tetrahedral voids present. Determine the formula of the compound formed by M and N ?

Explanation

N atoms make up ccp arrangement and there are two tetrahedral sites per atom of N.
No. of N atoms per unit cell = 4
No. of tetrahedral sites = `4 xx 2 = 8`
No. of sites occupied by `M = 1/3 xx 8 = 8/3`
`:.` No. of M atoms per unit cell = `8/3`
Formular `M_(8//3)N_4` or `M_8N_12` or `M_2N_3`.