- 
  
  Published his atomic theory which states that all matter is composed of atoms, all atoms of a given element are identical, compounds are formed by a combination of different types of atoms, and that a chemical reaction is a rearrangement of atoms.
- 
  
  Discovered that water was made up of two parts hydrogen and one part oxygen.
- 
  
  Dmitri Mendeleev arranged all the elements into the periodic table while creating his own chemistry text book.
- 
  
  Discovered the electron using a cathode ray tube. Believed that an atom was a sphere with positive material with negatively charged electrons stuck in it.
- 
  
  Discoverd radium and polonium along with Pierre Curie. Won two nobel prizes for chemistry and physics.
- 
  
  Shot alpha particles through peices of gold tin. Believed that the atom was mostly empty space with a dense positively charged nucleus surrounded by negatively charged electrons moving at a rapid pase.
- 
  
  Proposed that elements were more properly organized by positive nuclear charge than weight.
- 
  
  Believed the atom had a positively charged nucleus and was surrounded by electrons that travel in a circular orbit.
- 
  
  Won the nobel prize for his theory of Isotopes and further knowledge of radioactivity.