Particle model of matter

• What is density?


  Density is the mass per per unit volume
• Describe the methods to calculate density of regular shape?


  Measure sides using ruler, multiply to find a volume, measure mass using scale
• Describe method to calculate density of irregular shape?


  Measure mass using scale, a displacement can or other full of water, immerse object and measure volume of water displaced. and measure volume of water displaced. Volume of water equals volume of irregular object.
• What are the three states of matter?


  The three states of matter are solid, liquid, and gas.
• When a solid melt to a liquid does a change of mass occur?


  None, mass is always conserved in a phase change
• What do you call the phase transition from solid to liquid?


  Melting
• What do you call the phase transition from liquid to gas?


  Evaporation or boiling
• What do you call the phase transition from gas to liquid?


  Condensation
• What do you call the phase transition from liquid to solid?


  Freezing
• What do you call the phase transition from solid to gas?


  Sublimation
• What is the difference between boiling and evaporation?


  Boiling occurs throughout the whole substance bubbles and fast state change, evaporation only occurs on the surface slow
• Describe solid in terms of movement, arrangement and energy?


  Particles Vibrate about fixed points, fixed regular arrangement and lowest energy
• Describe solid in terms of movement, arrangement and energy?


  Particles vibrate in a regular regular arrangement and are free to move whilst still touching, medium energy
• Describe gases in terms of movement, arrangement and energy?


  Particles moving freely at a range of speeds, no fix the arrangement, have the highest energy
• Define melting point?


  Temperature at which a substance changes from solid to liquid or liquid to solid
• Define boiling point?


  Temperature at which a substance changes from liquid to gas or gas liquid
• When a substance changes state, why does the temperature not change?


  Energy goes into creating/breaking bonds, not heating the substance
• What happens in terms of internal energy when you go from solid to liquid to gas?

  As you go from gas to liquid to solid, internal energy increases
• Define internal energy?


  The sum of the vibrations or movement and the sum of the chemical potential energy
• How are temperature and kinetic energy linked?

  Temperature is the average kinetic energy of particles
• When a substance changes state, why does the temperature not change?


  Energy goes into breaking/forming bonds not increasing kinetic energy
• How does evaporation lower the internal energy of a substance?


  Only the fastest particles have enough energy to escape the surface of a liquid. If you remove the fastest particles the average kinetic energy lowers, and hence the temperature.
• How would you experimentally work out with the density of the metal cube?

  Measure mass in KG using scale, measure sides using a ruler, convert sides to metres, multiply sides together to find volume in metres cubed
• Describe the motion of particles in a liquid or gas?

  Random
• Describe how this motion leads to a pressure?

  Random motion, range of speeds

  Collide with each other and walls

  Each collision exerts a force, the sum of all these forces is the pressure
• What happens to the pressure of a gas if you heat it up at constant volume?


  Particles gain energy, particles move faster

  Collide more often and harder, higher pressure
• Define latent heat of fusion?

  The energy needed for a substance to change state. When a change of state occurs, the energy supplied changes the energy stored but not the temperature.
• Define latent heat of vaporisation?

  Specific latent heat of a substance is the amount of energy required to change the state of 1 kg of the substance with no change in temperature
• Define specific heat capacity?

  Specific heat capacity of a substance is the amount of energy required to raise the temperature of 1 kg of the substance by 1°C
• Describe how internal energy changes when a substance heated and does not change state?


  Internal energy increases kinetic energy energy increases potential energy stays the same
• Describe how internal energy changes when a substance is heated and does change?


  Internal energy increases, kinetic energy stays the same, potential energy increases
• What is the difference between physical and chemical change?

  Physical change is when particles have just been rearranged no new elements or compounds

  Chemical change is when new compound has been formed usually

  irreversible