Most non-metals exist as simple covalent molecules. In the solid state, the molecules are held together in a simple molecular lattice structure by weak intermolecular bonds.Carbon and silicon have a different structure. Their atoms are held together in a giant covalent lattice by strong covalent bonds.Substances with giant covalent lattice structures have high melting and boiling points because a lot of energy is needed to break the strong covalent bonds. They are insoluble in almost all solvents and are usually non-conductors of electricity (graphite is an exception).Diamond is a giant structure of carbon atoms covalently bonded to four other carbon atoms. The bonds spread through the structure so it is a giant structure.
Each carbon atom has four electrons in its outer shell so can form four single covalent bonds with other carbon atoms.The four electron pairs repel each other according to the electron pair repulsion theory. In three dimensions the bonds are tetrahedral with a bond angle of 109.5°.Diamond is very hard, has a very high melting point of about 3800K and does not conduct electricity because there are no free charged particles to carry charge.
Each carbon atom has four electrons in its outer shell so can form four single covalent bonds with other carbon atoms.The four electron pairs repel each other according to the electron pair repulsion theory. In three dimensions the bonds are tetrahedral with a bond angle of 109.5°.Diamond is very hard, has a very high melting point of about 3800K and does not conduct electricity because there are no free charged particles to carry charge.