History of atom

• JJ Thompson plum pudding model

  • Positively charged pudding
  • Negatively charged plums dotted around the pudding
  • His experiments concluded that atoms weren't solid spheres

  
• Gold foil experiment

  • Rutherford, Geiger and Marsden
  • Fired positively charged alpha particles at an extremely thin sheet of gold foil
  • Expecting the alpha particles to pass straight through
  • However some were deflected more than expected, with some even deflecting backwards
  • Therefore discovered the nucleus at the centre

  
• Niels Bohr

  • Suggested electrons existed in fixed orbits around the nucleus
  • Discovered electron shells