Liquid State

The liquid state, in brief

Intermolecular forces are stronger in liquids than in gases. Molecules in a liquid sit so close together that there is very little empty space between them — this is exactly why liquids are, under normal conditions, denser than gases.

Because attractive intermolecular forces hold liquid molecules together, a liquid has a definite volume — its molecules do not fly apart from one another the way a gas's do. At the same time, liquid molecules remain free to move past one another, which is why liquids can flow, be poured, and take up the shape of whatever container holds them (unlike a solid, but unlike a gas they don't expand to fill it). …