5Chapter 5Gases and the Kinetic-molecular TheoryGases consist of particles. The kinetic molecular theory accounts for the macroscopic gas behavior at the level of individual particles (atoms and molecules).Gas particles are tiny with large spaces between them. Gas particles have negligible volumes.Gas particles are in constant, random, straight-line motion except when they collide with each other or with the container walls. All collisions are elastic.Pressure:The particles are assumed to exert noforces on each other; they are assumed to neither attract nor repel each other.The average kinetic energy of a collection of gas particles is directly proportional to the kelvin temperature of the gas. (Kinetic energy = ½ mv2)According to the kinetic-molecular theory, molecules of different gases at the same temperature always have the same average kinetic energy. Average kinetic energy depends only on the temperature.