P3 - Particle model of matter

• Density

  How tightly packed an object is (of particles)

  
  

  mass/volume
• Measuring volume of a regular object

  Measure width, length and height using a ruler and multiply then together
• Measuring volume of an irregular object

  Use a eureka can. Fill until it is overflowing, place the object in and measure the water displaced using a measuring cylinder.
• Weighing scale

  Measure weight
• Balance

  Measure mass
• Measuring cylinder

  Measure volume
• Newton metre

  Measure force
• Solid

  - Particles are close together

  - Fixed, rigid, regular arrangement

  - Particles vibrate around a fixed position

  - Held together by strong forces of attraction

  
• Liquid

  - Particles are close together

  - Irregular, random arrangement

  - Particles move around each other, free to swap places

  - Held together more weakly

  - Take up the shape of a container

  
• Gas

  - Particles are far apart

  - Random arrangement

  - Move quickly and randomly in all directions

  - Weak forces of attraction between particles

  - Spread to fill the container

  - Can be compressed

  
• Kinetic energy

  Caused by random movement of particles, increases with temperature.
• Potential energy

  Caused by the forces between particles. Increases during melting and boiling (as bonds are breaking).
• Internal energy of a system

  Kinetic energy + Potential energy of particles
• Changing state graph


  flat horizontal line = change of state

  
• Pressure in gases

  - As the temperature increases, so does pressure (more kinetic energy)

  - As volume is decreased (gas compressed), the pressure increases

  - The pressure is created by the particles bouncing and pushing on the walls of the container (collisions)
• Boyle's Law

  - Describes the behaviour of gases

  - When gases are put under more pressure, their volume decreases (inversely proportional = curve on a graph)

  - Pressure is measure in Pascals (P)