Air, helium and chlorine are gases at room temperature. Water vapour is water as a gas. The particles in a gas are:
The particles in a gas can:
There are no bonds between the particles in a gas, so they are free to move in any direction.
The table shows some of the properties of gases and why they are like this:
|They flow and completely fill their container||The particles can move quickly in all directions|
|They can be compressed (squashed)||The particles are far apart and have space to move into|
The particles in a gas move quickly in all directions, but they do not get far before they bump into each other or the walls of their container. When gas particles hit the walls of their container they cause pressure. If the temperature is increased, the particles in a gas move faster, so they hit the walls of the container more often. This causes the pressure to rise. This is also why the pressure of a gas also increases when the volume of its container is decreased.