Question

Why is graphite a good conductor of electricity but diamond is a non-conductor of electricity?

Answer 1

Graphite is a good conductor of electricity because of the presence of free electrons in its crystal. As we know that an atom of carbon has 4 valence electrons, in a graphite crystal, each carbon atom is connected to only three other carbon atoms by covalent bonds. This means that the fourth valence electron of each carbon atom is free. These free moving electrons are responsible for the conduction of electricity in a graphite crystal. But in the case of diamond these free electrons are not available due to its structure. Hence, diamond is a non-conductor.