Ten Discoveries in Chemistry By Malachi Roldan Jan 1, 1772 Oxygen Discovery Jan 1, 1800 Atoms Combine into Molecules Jan 1, 1801 Electricity Transforms Chemical Jan 1, 1803 Atomic Theory Jan 1, 1828 Synthesis of Urea Jan 1, 1850 Atoms have Signatures of Light Jan 1, 1869 Periodic Table of Elements Jan 1, 1890 Radioactivity Jan 1, 1902 Electrons form Chemical Bonds Jan 1, 1969 Plastics