- In solids, the particles are held together by strong interparticle forces. These forces are strong enough to keep the particles in a fixed position, so solids have a definite shape and volume.

- In liquids, the interparticle forces are weaker than in solids, but still strong enough to keep the particles close together. This means that liquids can flow and take the shape of their container, but they do not have a definite shape.

- In gases, the interparticle forces are very weak. This means that the particles are far apart and can move around freely. Gases do not have a definite shape or volume.