Density

• Solids


  • Particles are very close together and arranged in a regular pattern
  • Particles vibrate but do not move from place to place
• Liquids


  • Particles are still close together but not arranged in a regular pattern
  • Particles can move around each other
• Gases


  • Particles are very far apart and not arranged in any pattern
  • Particles are moving very rapidly
• Density


  The mass for a given volume
• The equation for density is not given in the exam, so it's important to learn it
• A block of wood has a mass of 150 kg and a volume of 0.3 m^3. The density is 500 kg/m^3.
• Solids usually have high density


  Because particles are packed closely together, so they have a lot of mass for their volume
• Liquids usually have high density


  Because particles are close together, so they have a lot of mass for their volume
• Gases have low density


  Because particles are very far apart, so they only have a small mass for their volume
• Polystyrene is a solid with low density due to its open structure and air spaces