Atomic Theory Web Quest By aflei201 Oct 23, 1785 Law of Conservation of Mass Discovered by Antoine Lavoisier Oct 23, 1789 Antoine Lavoisier Proved The Law of Conservation of Mass Oct 23, 1806 Law of Definite Proportions Was Observed Mar 22, 1868 Robert Millikan Biorn Oct 23, 1887 JJ Thomson Discovered Electron Oct 23, 1899 Gold Foil Experiment Was Conducted Oct 23, 1904 JJ Thomson suggested Atomic Model Oct 23, 1905 Plum Pudding Atomic Model Proposed byJJ Thomson Oct 23, 1909 Oil Drop Experiment Performed by Robert Millikan Oct 23, 1910 Falling Drop Method Tested by Robert Millikan Oct 23, 1911 Planetary Model Proposed by Earnest Rutherford Oct 23, 1911 Earnest Rutherford Published finsings of Gold Foil Experiment Oct 23, 1925 Werner Heisenberg discovered way to Formulatr Quantun Mechanics Oct 23, 1932 James Chadwick Proved Existance of Neutrons Oct 23, 1932 Werner Heisenberg awarded Nobel Prize for 1925 discovery