P1 test

• Dalton’s Model 1803

  • Atoms are Indestructible
  • Solid spheres, identical within element but different between elements
• Thompson’s Model- Plum Pudding Model 1895

  • Negatively charged electrons
  • Positively charged sphere
• Rutherford Model 1905

  • Positively charged nucleus
  • Surrounded by electrons
• Rutherford Scattering Experiment

  Alpha particles shot at gold leaf, most went through, some deflected back
• Bohr Model 1913

  • Positively charged nucleus
  • Electrons in distinct energy levels (shells)
  • Electrons move between energy levels by emitting/absorbing radiation
• Chadwick Model

  • Discovered neutrons in nucleus
• Radius of an atom is 1 x 10^-10 m
• Density


  How much mass per volume, measured in kg/m³
• Density of solids and liquids are similar but much more dense than gases
• Law of Conservation of Mass

  Mass is neither created nor destroyed, mass before and after a physical reaction must be the same
• Particles can only be moved from one place to another, any missing mass must be lost via a leak (e.g. reduced mass of water after boiling, steam escaping)
• Temperature


  How hot or cold something is, measured in degrees Celsius (°C) or Kelvin (K)
• Energy


  Capacity to do work, measured in Joules (J)
• Increase in energy

  Can make chemical reactions happen easier by giving energy to atoms
• Increase in energy

  Can produce a change of state (e.g. ice to water)
• Chemical reaction

  Involves atoms separating and bonding to make new substances
• Physical change

  Involves rearrangement (movement) of atoms, is reversible
• Specific Heat Capacity

  Property of a material, energy needed to heat 1kg of material by 1°C
• Materials with high specific heat capacity need more energy to increase temperature, therefore they are poor conductors of heat and can be used as insulators
• Materials with low specific heat capacity need less energy to increase temperature, therefore they are good conductors of heat and can be used to transfer heat (e.g. cooking pans)
• Specific Latent Heat

  Property of a material, energy needed to change state (e.g. melt, boil)
• Specific Latent Heat of Melting

  Energy needed to change solid to liquid
• Specific Latent Heat of Vaporisation

  Energy needed to change liquid to gas
• Specific Latent Heat of Vaporisation is greater than Specific Latent Heat of Melting because the average energy of particles as a gas is greater than as a liquid
• Increasing temperature

  Increases gas pressure due to particles having more energy to travel and collide more often
• Decreasing temperature

  Decreases gas pressure due to particles having less energy to collide
• Increasing gas volume

  Decreases gas pressure due to particles having more space to spread out
• Decreasing gas volume

  Increases gas pressure due to particles having less space to spread out