Brownian motion: The random motion of particles suspended in a fluid. The movement occurs since the particles collide with other moving particles in the fluid.

Diffusion: The net movement of particles from an area of high concentration to an area of low concentration. Diffusion can only occur in fluids.

Gas: The state of matter where the particles have the most energy. The particles in a gas are relatively spread out and move randomly in all directions.

Kinetic theory: The theory which models the three states of matter by representing the particles as small solid spheres. Kinetic theory can help to explain melting, boiling, freezing, condensing and sublimation.

Liquid: The state of matter where the particles are arranged randomly and close together. The particles are able to move past each other.

Solid: The state of matter where the particles hold a regular arrangement and have the least amount of energy. The particles vibrate in fixed positions.

Sublimation: The process of a solid turning straight into a gas, without first becoming a liquid.

Some part is copied and written for educational purposes and i am not abusing here.