Particle model of matter

• What does the particle model of matter state?

  Everything is made up of lots of tiny particles.
• How does the particle model explain density?

  Density relates the mass of a substance to how much space it takes up.
• What is the formula for density?

  Density (kg/m³) = mass (kg) / volume (m³)
• What factors does density depend on?

  Density depends on what the material is made of and how its particles are arranged.
• What happens to the particles in a dense material when compressed?

  • Particles move closer together
  • Volume decreases without changing mass
• What are the three states of matter?

  Solid, liquid, and gas.
• How do the particles behave in solids?

  • Strong forces of attraction hold particles close together
  • Fixed, regular arrangement
  • Particles vibrate about fixed positions
• How do the particles behave in liquids?

  • Weaker forces of attraction between particles
  • Particles are close but can move past each other
  • Irregular arrangements and more energy than solids
• How do the particles behave in gases?

  • Almost no forces of attraction between particles
  • Particles have high energy and move freely
  • Travel in random directions at high speeds
• How do you find the volume of a regular solid?

  Measure its length, width, and height, then calculate using the relevant formula.
• How do you find the volume of an irregular solid?

  Submerge it in a eureka can filled with water and measure the displaced water.
• What is the first step to find the density of a liquid?

  Place a measuring cylinder on a balance and zero it.
• How do you calculate the density of a liquid?

  Record mass and volume, then use the density formula.
• What is internal energy?

  • Energy stored by the particles in a system
  • Includes kinetic and potential energy stores
• What happens to particles when a substance is heated?

  Particles gain energy in their kinetic stores and move faster.
• What are the five changes of state?

  Freezing, melting, boiling, evaporating, and condensing.
• Is a change of state a physical or chemical change?

  A change of state is a physical change.
• What happens to mass during a change of state?

  The mass stays the same; it is conserved.
• What causes the flat sections on a temperature-time graph during heating?

  Energy is being used to break bonds rather than raise temperature.
• What is specific latent heat?

  • Energy needed to change 1 kg of a substance from one state to another
  • Occurs without changing temperature
• What is the formula for specific latent heat?

  Energy (E) = Mass (m) × Specific Latent Heat (L)
• How much energy is needed to boil 1.50 kg of water at 100 °C if the specific latent heat of vaporisation is 2,260,000 J/kg?

  3,390,000 J
• How does temperature relate to the average energy in kinetic stores of gas particles?

  The higher the temperature, the higher the average energy in kinetic stores.
• What happens to gas particles when the temperature increases?

  The average speed of the particles increases.
• How do gas particles create pressure in a sealed container?

  They collide with the walls, exerting a force that creates pressure.
• What happens to gas pressure when the temperature increases at constant volume?

  The pressure of the gas increases.
• What is the relationship between pressure and volume for a fixed mass of gas at constant temperature?

  Pressure and volume are inversely proportional.
• What happens to the volume of a helium balloon when moved to an area of lower atmospheric pressure?

  The volume of helium in the balloon increases.
• Why does blowing up a football with a pump cause it to warm up?

  Doing work on the gas increases its internal energy and temperature.
• What are the key concepts related to particle motion in gases?

  • Gas particles move randomly at high speeds
  • Temperature relates to average kinetic energy
  • Pressure is created by collisions with container walls
  • Pressure increases with temperature at constant volume
  • Volume increases with decreasing pressure at constant temperature