Solids

• Solids have a fixed volume and shape and they have a high density.

• The atoms vibrate in position but can’t change location

• The particles are packed very closely together in a fixed and regular pattern

Liquids

• Liquids also have a fixed volume but adopt the shape of the container

• They are generally less dense than solids (an exception is water), but much denser than gases

• The particles move and slide past each other which is why liquids adopt the shape of the container and also why they are able to flow freely

Gases 

• Gases do not have a fixed volume, and, like liquids, take up the shape of the container

• Gases have a very low density

• Since there is a lot of space between the particles, gases can be compressed into a much smaller volume

• The particles are far apart and move randomly and quickly (around 500 m/s) in all directions

• They collide with each other and with the sides of the container (this is how pressure is created inside a can of gas)