Diamond

• Diamond is transparent and very hard while graphite is grey, black and soft. The differences are caused by the structure and bonding.
• Diamond exists as a joint covalent structure in which each carbon atom is covalently bonded to 4 other carbon atoms.
• Covalent bonds are very strong and diamond has many of them. This means diamond has a high melting point and it's very hard. This hardness makes diamond suitable for tips of dental drills.
• Diamond has no delocalised electrons so it does not conduct electricity.
• Diamond is hard, transparent, colourless and high melting point