Particle Model of Matter

• What is the definition of density?

  Mass per unit volume
• How is density calculated?

  Density = mass / volume
• What is the unit of density?

  kg/m³
• What are the characteristics of solids, liquids, and gases regarding particle arrangement and motion?

  • Solid: Regular arrangement, strong forces, vibration only
  • Liquid: Irregular arrangement, weak forces, small motion
  • Gas: Irregular arrangement, very weak forces, large motion
• What happens to density during changes of state?

  Density decreases when changing from solid to gas
• What is the definition of internal energy?

  Total energy stored by particles in a system
• What does heating a system do to its internal energy?

  It increases the internal energy of the system
• What are the two effects of heating a system?

  Increase temperature or change state
• What occurs during melting and boiling?

  1. Bonds between particles are broken.
  2. Internal energy increases; energy goes to potential energy stores.
  3. Temperature remains constant.
• What occurs during condensing and freezing?

  1. Stronger bonds form between particles.
  2. Internal energy decreases; energy is transferred away.
  3. Temperature remains constant.
• What is latent heat?

  Energy needed to change the state of a substance
• What is specific latent heat?

  Energy needed to change 1 kg of substance's state
• What is specific latent heat of fusion?

  Latent heat for changing between solid and liquid
• What is specific latent heat of vaporization?

  Latent heat for changing between liquid and gas
• What is specific heat capacity?

  Energy needed to raise 1 kg by 1 °C
• What happens when work is done on gases?

  Energy is transferred, increasing internal energy
• What causes gas pressure?

  Gas particles colliding with a surface
• What happens to gas pressure at constant temperature when volume increases?

  Pressure decreases as volume increases
• What happens to gas pressure at constant volume when external pressure changes?

  Gas expands if outside pressure is less
• How does temperature affect the average energy of gas particles?

  Higher temperature increases average kinetic energy
• What happens to gas particles as temperature increases?

  Particles move faster and collide more often
• What is the relationship between gas temperature and pressure?

  • Higher temperature leads to higher pressure
  • Increased particle speed results in more collisions
  • More collisions exert greater force on container walls