Density

• Density = A measure of how much mass is in a certain volume of a material
• Equation:

  • density = mass / volume
• As mass of a material is related to the particles it contains, the density of different states of the same material varies.
• SOLID

  • Particles are very closely packed - fixed in place together
  • Stronger forces between particles
  • Particles vibrate
  • Highest density
• SOLID diagram

  
• LIQUID

  • Particles still closely packed - move around each other but not free from each other
  • Weaker forces between particles
  • Lower density than in solids
• GAS

  • Particles widely spaced - particles are free and fast moving
  • Very weak forces between particles
  • Low density
• GAS diagram

  
• EXCEPTION

  • Ice has lower density than liquid - thats why ice cubes float to the top of glass of water.
• Density units:

  • g/cm^3
  • kg/m^3
• LIQUID diagram