Amber Hale Timeline By fhschemistry 300 Democritus' Theory Period: 300 to Jul 24, 1974 Scientists 350 Aristotle's Theory Oct 20, 1865 John Newlands Publishes Law of Octaves Oct 20, 1875 Crookes Tube Invented Oct 20, 1884 Dalton's Discoveries Oct 20, 1886 JJ Thomson Discovers Electron Oct 20, 1917 Rutherford Splits Atom Oct 20, 1922 Bohr Wins Nobel Prize for Atomic Model Oct 20, 1932 Chadwick Discovers Neutron Oct 20, 1932 Chadwick Discover's Neutron Oct 20, 1960 Mendeleev Created First Version of Periodic Table