particle model of matter

• What is the formula for density?

  Density = mass/volume
• What units are used for density?

  Kilograms per metre cubed (kg/m³)
• What does density depend on?

  Spacing of the atoms in matter
• How do the densities of solids, liquids, and gases compare?

  • Solids and liquids have similar densities
  • Liquids usually have lower density than solids (except ice)
  • Gases have far lower density than solids/liquids
• Why do gases have lower density than solids?

  Particles have more energy and occupy greater volume
• What happens to mass during a change of state?

  Mass is conserved
• If 20g of liquid evaporates, what is the weight of the gas produced?

  20g
• What are the changes of state between solid, liquid, and gas?

  • Solid ⇌ Melting ⇌ Liquid ⇌ Evaporating ⇌ Gas
  • Freezing ⇌ Condensing ⇌
• Why are changes of state considered physical changes?

  Materials retain their original properties when reversed
• What is internal energy?

  Energy stored by particles within a system
• What forms can internal energy take?

  Kinetic and potential energy
• What happens to internal energy when a system is heated?

  It increases
• What effect does heating have on the temperature of a system?

  It increases the temperature
• What is pressure in the context of gas particles?

  Collision of gas particles with container walls
• How does temperature affect the average kinetic energy of gas particles?

  Higher temperature increases average kinetic energy
• What happens to pressure when the volume of a gas is decreased?

  Pressure increases
• What is the relationship between pressure and volume of a gas at constant temperature?

  • Pressure is inversely proportional to volume
  • Decreasing volume increases pressure
  • More frequent collisions with container walls
• What is the equation relating pressure and volume of a gas?

  P₁V₁ = P₂V₂
• What happens when work is done on a gas?

  Its volume decreases
• What is the formula for work done on a gas?

  Work done = Force × Distance
• How does adding more particles to a fixed volume affect pressure?

  Pressure increases
• What happens to pressure if the mass of gas particles changes but the number remains the same?

  Pressure remains the same
• How does particle velocity relate to pressure in a gas?

  Higher velocity leads to greater pressure