Atomic structure and the periodic table

• Alpha-scattering experiment


  1. Take gold foil

  2. Fire alpha particles at gold foil

  3. Most pass through, some deflect, some bounce back

  4. Replaced plum pudding model with nuclear model
• The Nuclear Model:

  • Niels Bohr proposed that electrons orbit the nucleus at specific distances
  • Tiny positive particles are called protons which are in nucleus
  • James Chadwick discovered that the nucleus also contains neutral particles called neutrons.
  • Relative charge for proton = +1, Relative charge for neutron = 0, relative charge for electron = -1
  • Relative mass for proton and neutron = 1, relative mass for neutron = very small.
  • Atoms have no overall charge
• Simple distillation


  Used to separate a dissolved solid from a liquid
• Simple distillation process


  1. Evaporate liquid by heating, turning it to vapour

  2. Condense vapour back to liquid by cooling
• Dobereiner's Triads


  • Elements with similar chemical properties often occurred in threes e.g. lithium, sodium and potassium
• Newlands' Law of Octaves


  • Arranged elements in order of increasing atomic weight, saw that every eighth element reacts in a similar way
• Dmitri Mendeleev


  Created the modern periodic table
• Group 0 elements weren't discovered when Mendeleev created the periodic table