Explaining the states of matter

In the solid state, particles are very close together because the attractive forces between them are very strong. These forces give the particles cohesion and little freedom of movement. Their movement is limited to vibration.

According to the kinetic theory, solids are particles that are strongly joined together, like a collection of marbles. This explains why they have a fixed shape and a fixed volume. There is empty space between the particles, and they vibrate continuously, but they stay in a fixed position. This is like shaking a jar of marbles quickly.

In the liquid state, particles are further apart than in the solid state. There is less cohesion between them because the attractive forces are less strong (or weaker). They vibrate, and they can also move around.

Like solids, the liquid state can also be explained with the kinetic theory. According to this theory, the forces between the particles are weaker than in solids. This explains their ability to flow (change shape easily). However, they cannot expand indefinitely. This explains why they have a fixed volume but no fixed shape.

In the gaseous state, particles are very far apart because the attractive forces are insignificant (or very weak). Because of this, they have no cohesion and, in addition to vibrating, they move freely.