Density

• In solids, the particles are very close together and arranged in a regular pattern, vibrating but not moving from place to place.
• In liquids, the particles are still close together but they're not arranged in a regular pattern, and can move around each other.
• In gases, the particles are very far apart and not arranged in any pattern, moving very rapidly.
• The density of material tells us the mass for a given volume.
• The unit of density is kilograms per meter cubed.
• The density of a block of wood with a mass of 150 kilograms and a volume of 0.3 meters cubed is 500 kilograms per meter cubed.
• Solids usually have a very high density because the particles are packed closely together, having a lot of mass for their volume.
• Liquids usually have a high density because the particles are close together, having a lot of mass for their volume.
• Gases have a low density because the particles are very far apart, having only a small mass for their volume.
• Polystyrene, which is a solid, has a low density due to the very open structure filled with air spaces, having a smaller mass for its volume.