Answer to Question #302099 in General Chemistry for Hutchii

Question

Explain why diamond is harder than graphite. Why is graphite an electrical conductor but diamond is not?

Answer 1

Diamond is harder than graphite because it is crystalline form of carbon and each carbon is bonded with four other carbon atoms with strong covalent bond.These carbon atoms in graphite have the tendency to bond with weaker intermolecular forces such that these layers slide over each other. This is the reason why diamond is harder than graphite.

Graphite is an electrical conductor but diamond is not because of the delocalised electrons in its structure. These arise because each carbon atom is only bonded to 3 other carbon atoms. But in diamond, all 4 outer electrons on each carbon atom are used in covalent bonding, that is why there are no delocalised electrons in its structure so that it can conduct electricity.