Question

Statement: In diamond, co-ordination number of carbon is $4$ and it's unit cell has $8$ carbon atoms.

State whether the given statement is true or false.

• A. True
• B. False

Answer 1

The correct option is A True

In diamond, the co-ordination number of carbon is 4 and its unit cell has 8 carbon atoms.

Diamond has the face centred cubic unit cell. The $C$ atoms are present at corners, at face centres and in half of the tetrahedral voids.

The contribution of corner $C$ atom to the unit cell is one eight, the contribution of face centre $C$ atom to the unit cell is one-half and the contribution of $C$ atom in the tetrahedral void is 1. The number of $C$ atoms per unit cell $=8\times \frac{1}{8}+6\times \frac{1}{2}+4=1+3+4=8$
Each $C$ atom is at the centre of the tetrahedron and is surrounded by 4 $C$ atoms present at 4 corners of a tetrahedron.

Hence, the co-ordination number of carbon is 4.

Hence, the given substance is $\text{true}$