Question

In a CCP lattice of A and B, A atoms are present at the corners while B atoms are at face centres.
Then the formula of the compound would be if one of the A atoms from a corner is replaced by C
atoms (also monovalent)?

Answer 1

1. Contribution of corner is 1/8 for A atom.

2. Ideally:

A = $\frac{1}{8}\times 8=1$ B =$\frac{1}{2}\times 6=3$

Formula = AB₃

3. If one A is replace by C, the formula becomes:
$A_{1-\frac{1}{8}}{B}_3{C}_{\frac{1}{8}}or{A}_{\frac{7}{8}}{B}_3{C}_{\frac{1}{8}}or{A}_7{B}_{24}C$