Development of the atom

• Dalton's model 1803

  
  

  Atoms - tiny balls that cannot be broken down into anything else

  During chemical reactions, atoms rearrange to make different substances
• Thomson's model 1897

  
  

  Electron discovered - led to plum pudding model

  Atoms are spheres of positive charge with electrons dotted around inside
• Rutherford's model (1909)

  
  

  Proton discovered

  Elecrons orbit a massive nucleus

  Mostly empty space
• Bohr's model (1932)

  
  

  Electrons are found on shells or energy levels around the nucleus