The Kinetic Theory of Gases describes the behavior of gases in terms of motion on the particle or microscopic level. There are different ways in which the assumptions can be stated and grouped. At minimum, there are five postulates:
1. Gases consist of particles in random, rapid motion. The particles move in a straight line until they collide with other gas particles or with the walls of their container.
2. The volume of the particles is essentially zero compared to the volume of the container. In other words, the molecules are like dimensionless points.
3. There are no forces of attraction or repulsion between the gas particles.
4. Collisions with the walls of the container or with other particles are perfectly elastic, meaning that no energy is lost.
5. The average kinetic energy of a sample of gas particles depends on the temperature of the gas.