13 Great Discoveries of Chem By Malachi Roldan 1770 Oxygen Period: 1807 to 1810 Electricity transforms chemicals 1808 Atomic theory 1811 Atoms combine into molecules 1828 Synthesis of urea 1850 Chemical structure 1850 Atoms have signatures of light Period: 1860 to 1880 Periodic table Period: 1869 to 1909 Plastics Period: 1890 to 1909 Radioactivity 1897 Electron 1913 Electrons for Chemical bonds 1985 Fullerenes