Chemistry – States of matter - Solids, liquids and gases | e-Consult

When a substance changes from a solid to a liquid (melting), the particles gain kinetic energy. In the solid state, particles are held in fixed positions by strong intermolecular forces. As the temperature increases during melting, the particles vibrate more vigorously. Eventually, the particles gain enough kinetic energy to overcome the intermolecular forces holding them in fixed positions. This allows the particles to move more freely, resulting in a less ordered arrangement and a state where the substance can flow. The intermolecular forces are still present in the liquid state, but they are weaker than in the solid state. The particles are closer together in the liquid state than they are in the gaseous state, but further apart than they are in the solid state.