particle model of matter

• solids 


  strong forces of attraction close together structure in a fixed regular arrangement,

  Particles don’t have much energy

  Density is generally highest in this state
• liquids 


  weaker forces of attraction between particles - particles are close together but can move past each other form an irregular arrangement- has more energy than a solid but less than a gas

  Move in random directions at low speeds

  Less dense than solids
• gases 


  almost no force of attraction - most energy- particles move freely and travel in random directions at high speeds

  Gases have low densities
• Density


  The amount of mass per unit volume of a substance
• Solids are generally denser than liquids, and gases are usually less dense than liquids
• To find the density of a solid object

  1. Measure mass using a balance

  2. Find volume using a formula or water displacement

  3. Plug mass and volume into density formula
• To find the density of a liquid

  1. Place measuring cylinder on balance and zero

  2. Pour 10ml of liquid, record mass

  3. Repeat with more 10ml portions, record total volume and mass

  4. Calculate density for each measurement, then take average
• 1 ml = 1 cm³
• Changes of state conserves of mass

  SOLID to LIQUID = melting

  LIQUID to SOLID = freezing

  LIQUID to GAS = evaporation

  GAS to LIQUID = condensation

  SOLID to GAS = sublimation
• specific latent heat 


  Energy needed to change state