Particle Model of Matter

• What is the formula for change in thermal energy?

  Mass times specific heat capacity times temperature change
• What happens to a substance during a chemical change?

  Its chemical structure changes and properties may not restore
• What is condensation?

  Changing from vapour state to liquid state
• How is density defined?

  Mass per unit volume of an object
• What is evaporation?

  Changing from liquid state to vapour state when heated
• What is freezing?

  Changing from liquid state to solid state when cooled
• How is gas temperature related to kinetic energy?

  Gas temperature is directly proportional to average kinetic energy
• What is internal energy?

  Energy stored by atoms and molecules in a system
• What is latent heat?

  Energy required for a substance to change state
• What is melting?

  Changing from solid state to liquid state when heated
• What is the unit of pressure?

  Pascals
• How is pressure defined?

  Force acting perpendicular to a surface per unit area
• What is specific heat capacity?

  Energy needed to raise temperature of 1 kg by 1°C
• What is specific latent heat of fusion?

  Energy needed to change 1 kg solid to liquid at constant temperature
• What is specific latent heat of vaporisation?

  Energy needed to change 1 kg liquid to vapour at constant temperature
• What is specific latent heat?

  Energy needed to change state of 1 kg at constant temperature
• What is sublimation?

  Direct changing from solid state to vapour state
• What are the types of changes in matter?

  • Chemical Changes: Alter chemical structure, irreversible
  • Physical Changes: Alter physical properties, reversible
  • Changes of State: Physical changes, properties restore
• What is the definition of density?

  Density is mass per unit volume
• What are the definitions of specific latent heats?

  • Specific Latent Heat of Fusion: Energy to change solid to liquid
  • Specific Latent Heat of Vaporisation: Energy to change liquid to vapour
  • Specific Latent Heat: General term for energy to change state
• How is density mathematically expressed?

  Density ρ = mass m / volume V
• What are the units of density?

  kg/m³
• How does density relate to the spacing of atoms in matter?

  Density depends on the spacing of atoms
• Why do solids and liquids have similar densities?

  Because the spacing between particles does not change
• What is the general density relationship between liquids and solids?

  Liquids usually have lower density than solids
• What is the exception to the general density relationship between liquids and solids?

  Ice has a lower density than water
• How does the density of gases compare to that of solids and liquids?

  Gases have a far lower density
• What happens to the spacing between atoms in gases compared to solids?

  The spacing increases by a factor of ten
• What happens to the density of a gas when its volume increases greatly?

  The density decreases greatly
• What is conserved during a change of state?

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

  The gas will weigh 20g
• Why are changes of state considered physical changes?

  Because the material retains its original properties
• What are the changes of state for matter?

  • Melting
  • Freezing
  • Evaporating
  • Condensing
  • Sublimation
• What is internal energy in a system?

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

  Kinetic and potential energy
• What happens to the energy of particles when a system is heated?

  The energy of the particles increases
• What does specific heat capacity measure?

  Energy required to raise temperature of 1kg
• What is the formula for change in thermal energy?

  ∆E = m × c × ∆T
• What does ∆E represent in the thermal energy formula?

  Change in thermal energy in joules
• What is specific latent heat?

  Energy needed to change state without temperature change