Particle Model of Matter

• What is density a measure of?

  Density is a measure of the 'compactness' of a substance.
• What factors affect the density of an object?

  The density of an object depends on what it is made of and how its particles are arranged.
• How do the particles in different states of matter compare?

  The particles of a substance in each state are the same, but their arrangement and energy differ.
• What are the three states of matter?

  • Solids
  • Liquids
  • Gases
• What are the characteristics of solids?

  • Strong forces of attraction hold particles close together.
  • Fixed, regular arrangement of particles.
  • Particles vibrate about fixed positions.
  • Solids have the highest density.
• What are the characteristics of liquids?

  • Weaker forces of attraction between particles.
  • Particles are close together but can move past each other.
  • Irregular arrangements of particles.
  • Liquids are generally less dense than solids.
• What are the characteristics of gases?

  • Almost no forces of attraction between particles.
  • Particles have the most energy and move freely.
  • Travel in random directions at high speeds.
  • Gases have the lowest densities.
• What are the steps to measure the density of a solid object?

  1. Measure mass using a balance.
  2. For regular solids, measure length, width, height, and calculate volume.
  3. For irregular solids, submerge in water and measure displaced volume.
  4. Use the formula \( \rho = \frac{m}{V} \) to find density.
• What are the steps to measure the density of a liquid?

  1. Zero the balance with a measuring cylinder.
  2. Pour 10ml of liquid, record mass.
  3. Repeat until full, recording total volume and mass.
  4. Calculate density for each measurement and take an average.
• What is a change of state?

  A change of state is a physical change where the same substance is in a different form.
• What happens to the number of particles during a change of state?

  The number of particles doesn't change; they are just arranged differently.
• What are the changes of state between solid, liquid, and gas?

  • Solid to Liquid: Melting
  • Liquid to Solid: Freezing
  • Solid to Gas: Sublimation
  • Gas to Liquid: Condensation
  • Liquid to Gas: Evaporation
  • Gas to Solid: Deposition
• What is internal energy?

  Internal energy is the total energy that particles have in their kinetic and potential energy stores.
• How does heating a system affect its internal energy?

  Heating a system transfers energy to the particles, increasing the internal energy.
• What is specific heat capacity?

  Specific heat capacity is the amount of energy required to raise the temperature of one kilogram of a substance by one degree Celsius.
• What is the formula for calculating change in thermal energy?

  The formula is \( \text{Change in thermal energy} = \text{mass} \times \text{specific heat} \times \text{temperature change} \).
• What is latent heat?

  Latent heat is the energy needed for a substance to change state without changing temperature.
• What happens to energy during melting or boiling?

  Energy is used to break intermolecular bonds, increasing internal energy.
• What happens to energy during condensing or freezing?

  Energy is released as bonds form between particles, decreasing internal energy.
• What is the specific latent heat of fusion?

  Specific latent heat of fusion is the energy needed to change state from solid to liquid.
• What is the specific latent heat of vaporisation?

  Specific latent heat of vaporisation is the energy needed to change state from liquid to vapour.
• How is energy for a change of state calculated?

  Energy for a change of state is calculated using the formula \( \text{Energy} = \text{mass} \times \text{specific latent heat} \).
• How does temperature affect gas particles?

  Increasing the temperature transfers energy into the kinetic energy stores of gas particles.
• What is the relationship between temperature and average kinetic energy in gases?

  The temperature of a gas is related to the average kinetic energy of its particles.
• How does increasing temperature affect gas pressure?

  Increasing temperature increases the average speed of gas particles, which increases pressure.
• What causes gas pressure in a sealed container?

  Gas pressure is caused by particles colliding with the walls of the container and exerting force.
• What happens to gas pressure if the volume increases at constant temperature?

  If volume increases, gas particles get more spread out and hit the walls less frequently, decreasing pressure.
• What is the relationship between pressure and volume for a fixed mass of gas at constant temperature?

  Pressure and volume are inversely proportional; as volume increases, pressure decreases.
• What is the formula that describes the relationship between pressure and volume for a gas?

  The formula is \( P \times V = \text{constant} \).
• What happens to a container if the pressure inside it changes?

  If the pressure changes, the container may compress or expand depending on the overall force.
• What happens to a helium balloon when it is released?

  The balloon rises because atmospheric pressure decreases with height, causing it to expand.
• How does doing work on a gas affect its internal energy?

  Doing work on a gas increases its internal energy, which can increase its temperature.
• How does a bike pump demonstrate work done on a gas?

  A bike pump exerts force on the gas, doing work that increases the kinetic energy of the gas particles.