A particle diagram is a visual representation of the particles of a substance, with the particles typically represented as dots. Digital particle diagrams can also show the movement of particles within a particular substance.
A general particle diagram for a solid shows the particles located close together in a regular pattern. A moving particle diagram can show the particles of a solid vibrating in place. However, a particle diagram for a gas may show the particles far apart and in an irregular pattern or random arrangement. If the particle diagram also shows movement, it illustrates the gas particles moving quickly in all directions.