Kinetic Molecular Theory
The kinetic energy of a gas is proportional to its temperature.
Gas particles are in continuous, random motion.
The volume of a gas is negligible compared to the volume of its container.
The velocity of a gas particle is proportional to its temperature and mass.
Gases have no intermolecular forces. In other words, gases do not attract or repel each other.
Gas particle collisions are elastic - they do not lose kinetic energy when they collide.