Atomic Structure

Atomic Structure

1. Atomic Model

   • Dalton's model
     • 'All matter is made of atoms'
     • 'Atoms cannot be split'
     • 1803
   • Thomson's model
     • The 'plum pudding' model
     • 1897
     • 'A ball of positive charge'
     • 'Negatively charged electrons mixed in the positive'
   • Rutherford's Model
     • 1909
     • Discovered alpha particles bouncing off gold foil
     • 'An atom's mass is concentrated at the centre'
       • Centre called a nucleus
   • Modern model
     • Bohr
       • 'Electrons orbit the nucleus at fixed distances'
     • Chadwick
       • 1932
       • 'Some particles do not contain any charge'
         • Called neutrons
   • Subatomic particles
     • Proton
       • Charge = +1
       • Found in nucleus
       • Mass = 1
     • Neutron
       • Charge = 0
       • Found in nucleus
       • Mass = 1
     • Electron
       • Charge = -1
       • Found in orbit around nucleus
       • Mass < 0

2. Isotopes

   • Isotopes of Hydrogen
     • Protium
       • 1 proton, 0 neutrons
       • 99.98% of Hydrogen
       • Uses
         • Hydrogen fuel cells
         • Production of plastics
     • Deuterium
       • 1 proton, 1 neutron
       • 0.02% of Hydrogen
       • Uses
         • Nuclear Fusion
     • Tritium
       • 1 proton, 2 neutrons
       • Rare
       • Uses
         • Thermonuclear fusion weapons
   • Forms of an element with the same number of protons but different number of electrons
   • Nuclides
     • Refers to a specific nucleus of x protons and y electrons

3. Relative Atomic Mass

   • Average mass of all isotopes in a sample