The amount of energy needed to change the state of a substance therefore depends on the amount of energy needed to separate the particles.

This, in turn, depends on the type of particle and the nature of the bonding between them.

Substances which have strong intermolecular forces will require more energy to move from solid to liquid to gas. This means they will have higher boiling points.

Ionic compounds experience stronger intermolecular forces than covalent compounds.

Bigger molecules experience stronger intermolecular forces than small ones