History of the Atom By zjsimo24 Period: 370 to 460 Democritus Life Span This is backwords because it won't allow it to be in BC. Period: Oct 2, 1766 to Oct 2, 1844 John Dalton Life Span Oct 2, 1801 John Dalton - Different elements have different atoms Period: Dec 18, 1856 to Aug 30, 1940 JJ Thomson Life Span Period: Mar 22, 1868 to Dec 19, 1953 Robert Millikan Life Span Period: Aug 30, 1871 to Oct 19, 1937 Ernest Rutherford Life Span Period: Oct 7, 1885 to Nov 18, 1962 Neils Bohr Life Span Period: Oct 20, 1891 to Jul 24, 1974 James Chadwick Life Span Oct 2, 1897 JJ Thomson - Discovered Electron Oct 2, 1910 Robert Millikan - Found charge of an electron to be negative Oct 2, 1910 Ernest Rutherford - Rutherford Atomic Model Oct 2, 1913 Neils Bohr - Bohr's Atomic Model Oct 2, 1932 James Chadwick - Discovered Nucleus Mar 2, 2022 Democritus - Atomic Theory