Covalent and non-metals generally have low melting points because the forces holding them together are relatively weak. However, there are some exceptions to this rule. For example, diamond, which is made of pure carbon, has a very high melting point (3550 °C). This is because the carbon atoms in diamond are bonded together in a very strong covalent network. Another example is silicon carbide (SiC), which also has a high melting point (2730 °C).

In general, compounds that have high melting points tend to be ionic or polar covalent, rather than covalent and non-metal. This is because the electrostatic forces between ions or polar molecules are stronger than the covalent bonds between non-metals.