Final answer:
Gases are composed of particles in constant motion, colliding elastically without energy loss. The kinetic theory of gases explains how these collisions result in pressure within a container. Temperature in kelvin is directly related to the average kinetic energy of the particles.
Step-by-step explanation:
Gases consist of tiny particles of matter that are in constant motion. These gas particles are frequently colliding with each other and the walls of a container. An important property of these collisions is that they are elastic, meaning there is no net loss of energy during the collisions, allowing the particles to continue in motion indefinitely.
Furthermore, gas molecules exert no attractive or repulsive forces on one another or on the walls of the container. This lack of interaction ensures that collisions remain elastic. The average kinetic energy of gas molecules, which defines their speed, is proportional to the gas's temperature measured in kelvin.
The theory that explains these behaviors is known as the kinetic theory of gases. According to this theory, the high-speed collisions of gas particles with the container walls result in pressure. This pressure is the result of the collective force of the particles upon the container's surfaces and is entirely based on how often and how forcefully the particles collide.