Let's move up from the level of individual gas molecules and take a look at gaseous substances.

In chemistry, the model of an 'ideal' gas is used to understand gas behavior. For an ‘ideal’ gas, the volume of the gas particles is extremely small compared to the volume of the container and the gas molecules exert no intermolecular forces on one another. Real gases are never perfectly 'ideal', but their basic properties can still be described using the ‘ideal' gas model. In an ideal gas:

• Gas particles are in continuous, random motion and collide with other particles
• The temperature of a gas is proportional to the average kinetic energy of the gas molecules
• At the same temperature the average kinetic energy of a gas is the same for all gases, regardless of their size or mass