Structure and properties of graphite

Graphite is a giant covalent form of carbon. Its carbon atoms form large, flat layers. Within each layer, every carbon atom forms three strong covalent bonds with three other carbon atoms, producing a pattern of hexagonal rings.

Electrical conductivity of graphite

Each carbon atom has one electron that is not used in its three covalent bonds. These electrons become delocalised: they are not confined to a particular atom and can move through the layers. They carry electrical charge, so graphite conducts electricity. It is similar to metals in this respect.

Strength and softness of graphite

The covalent bonds within each layer are strong. A large amount of energy is needed to break them, giving graphite a high melting point.

There are no covalent bonds between the layers; only weak forces hold them together. The layers can therefore slide over one another easily, making graphite soft and slippery, even though the bonds within each layer are strong.