The kinetic theory of gases explains the macroscopic properties of gases, such as volume, pressure, and temperature, as well as transport properties such as viscosity, thermal conductivity and mass diffusivity. The basic version of the model describes the ideal gas, and considers no other interactions between the particles. The particles undergo random elastic collisions between themselves and with the enclosing walls of the container. Their size is assumed to be much smaller than the average distance between the particles. The model describes a gas as a large number of identical submicroscopic particles ( atoms or molecules), all of which are in constant, rapid, random motion.
The kinetic theory of gases is a simple, historically significant classical model of the thermodynamic behavior of gases, with which many principal concepts of thermodynamics were established. The atoms have an average speed relative to their size slowed down here two trillion fold from that at room temperature. The size of helium atoms relative to their spacing is shown to scale under 1950 atmospheres of pressure. Historic physical model of gases The temperature of the ideal gas is proportional to the average kinetic energy of its particles.
