Democritus proposes existence of atoms.
400 B.C. - 300 B.C.
Antoine Lavoisier discovers Law of Conservation of Mass.
John Dalton proposes first atomic theory of matter.
Dimitri Mendeleev develops and publishes Periodic Table.
Niels Bohr is born in Copenhagen, Denmark.
October 7, 1885
JJ Thomson discovers electron.
Ernest Rutherford proposes positive nucleus and negative electron orbits.
Niels Bohr is introduced to Rutherford.
Niels Bohr creates own atomic model.
Niels Bohr receives Nobel Prize.
James Chadwick proves existence of neutrons.
Niels Bohr dies in Copenhagen, Denmark.
November 18, 1962