history of the atom

• John Dalton


  1803; Atomic Theory: all matter made of atoms; all atoms of an element are alike, but are different from other elements; elements can be combined to make compounds; chemical reactions are a rearrangement of elements, but do not change the elements themselves.

  
• JJ Thomson


  1897; finds the electron of an atom using a cathode ray tube; also said the electron must be balanced by positive charge; proposed the plum pudding model.

  
• Ernest Rutherford


  1911; performed the gold foil experiment; proved that most of the atom is empty space and the existence of the nucleus.

  
• Niels Bohr


  Electrons should move around the nucleus but only in prescribed orbits
• james chadwick


  1932-Discovered the neutron and that its mass is the same as the proton. This led to development of atomic energy.