Diamond and graphite are allotropes of carbon which have giant covalent structures
Both substances contain only carbon atoms but due to the differences in bonding arrangements they are physically completely different
Giant covalent structures contain billions of non-metal atoms, each joined to adjacent atoms by covalent bonds forming a giant lattice structure
Diamond
In diamond, each carbon atom bonds with four other carbons, forming a tetrahedron
All the covalent bonds are identical, very strong and there are no intermolecular forces
