- 
  
  Democritus made a prediction about how atoms were and looked like
- 
  
  Dalton does experiments and improves on democritus's theory
- 
  
  J.J. thomson discovers electrons and makes the plum pudding model of the atom
- 
  
  He proved that an atom must contain a central nucleus.This was further evidence that an atom contained smaller pieces.
- 
  
  He proved that electrons occupy particular orbits or shells around the nucleus of an atom