$A$ and $B$ atoms in a crystal are positioned at the corners and face centers respectively. What is the…
$A$ and $B$ atoms in a crystal are positioned at the corners and face centers respectively. What is the formula of the crystal?
$A_2 B_3$
$A B_2$
$A B_3$
$A_2 B_3$
Solution
Atoms of $A$ are placed at the corners in a crystal. Thus, its contribution $=\frac{1}{8} \times 8=1$.
Atoms of $B$ are placed at the face centres in the given crystal. Thus, their contribution $=6 \times \frac{1}{2}=3$.
Therefore, the formula of the crystal is $A B_3$.