1.3 Particles model of matter

• What is the definition of density?

  The mass per unit volume of a material
• What is the equation for density?

  ⍴ = m/v
• What are the units for density?

  kg/m³
• What is the least dense state of matter?

  Gas
• What is the order of states of matter from least to most dense?

  Gas, Liquid, Solid
• How are particles arranged in a solid?

  Tightly packed in a regular arrangement
• How do particles behave in a solid?

  Particles can only vibrate on the spot
• How are particles arranged in a liquid?

  Close together, but with an irregular arrangement
• How do particles behave in a liquid?

  They can flow over each other
• How are particles arranged in a gas?

  Separated, with no regular arrangement
• How do particles behave in a gas?

  Particles can move freely
• What is always conserved during a change of state?

  Mass
• How does a change of state differ from a chemical change?

  Material can return to previous properties
• What is sublimation?

  Solid changes into gas without liquid state
• What is evaporation?

  Liquid changes into gas state
• What is the opposite of evaporation?

  Condensation
• What happens during condensation?

  Gas changes into a liquid state
• Why does the mass of boiling water appear to decrease?

  Some water evaporates and turns into vapor
• What remains constant in the boiling water system?

  The mass of the whole system
• What processes occur when a bathroom mirror mists up?

  • Hot water evaporates to form water vapor
  • Water vapor lands on the cooler mirror
  • Vapor condenses and returns to liquid state
• What is the internal energy of a substance?

  The energy stored by the particles
• What does the internal energy of a substance consist of?

  The sum of total kinetic and potential energies
• How does heating affect the energy of a substance?

  Heating transfers energy to the substance
• What happens to the energy of particles when a substance is heated?

  It increases the energy of the particles
• What two effects can heating a substance have?

  1. Raise its temperature
  2. Change the state of the substance
• What three factors determine the temperature change of a system?

  1. Mass of substance being heated
  2. Type of material (Specific heat capacity)
  3. Energy inputted into the system
• What is the equation used to calculate the temperature change when a substance is heated?

  ΔE = m c Δ��
• What are the appropriate units for energy, mass, specific heat capacity, and temperature in the equation ΔE = m c Δ𝛉?

  Energy (J), Mass (kg), Specific Heat Capacity (J/kg/°C), Temperature (°C)
• What is specific heat capacity?

  Energy needed to raise 1kg by 1°C
• How does the internal energy and temperature of a substance change during a change of state?

  Internal energy changes, temperature remains constant
• What is specific latent heat?

  Energy needed to change state of 1kg without temperature change
• What is the equation for the energy required to change state?

  Energy to change state = mass x specific latent heat
• What are the appropriate units for energy, mass, and specific latent heat in the equation for energy required to change state?

  Energy (J), Mass (kg), Specific latent heat (J/kg)
• What is the specific latent heat of fusion?

  Energy to change 1kg from solid to liquid
• What is the specific latent heat of vaporisation?

  Energy to change 1kg from liquid to gas
• What is the motion of molecules in a gas?

  They are in constant random motion.
• What factor affects the average kinetic energy of gas molecules?

  The temperature of the substance
• How does temperature affect the average kinetic energy of gas molecules?

  The higher the temperature, the higher the average kinetic energy.
• What happens to the pressure of a gas when temperature increases at constant volume?

  Pressure of the gas will increase.
• Why does pressure increase as temperature increases at constant volume?

  Kinetic energy of molecules increases.