Chemistry Question on The solid state

Question

In diamond, each carbon atom is bonded to four other carbon atoms tetrahedrally. The number of carbon atoms per unit cell is

Answer 1

Solution

Structure of diamond can be visualised as an $f.c.c.$ arrangement of carbon atoms in which carbon atoms are also present in alternate tetrahedral sites. In such a way each carbon atom has a $C.N$ . of $4$ . No. of atoms per unit cell. $= 8\times \frac{1}{8} + 6 \times \frac{1}{2} +4 \times 1$ $= 1 + 3 + 4 = 8$ (Eight corners, six face centres and half of the $8$ tetrahedral sites)