History of the Periodic Table By nicole_hunt14 Aug 14, 1680 Robert Boyle discovered phosphrus Sep 14, 1809 47 elements were discovered and scientists began to see patterns in the characteristics Sep 14, 1863 John Newlands divided 56 elements into 11 groups, based on characteristics Sep 14, 1869 Dimitri Mendeleer started the development of the periodic table, arranging chemical elements by atomic mass Sep 14, 1894 Sir William Ramsay and Lord Rayleigh discovered noble gases , which were added to the periodic table as group 0. Sep 14, 1897 J.J. Thompson discovered electrons Sep 14, 1911 Rutherford and Hans Geiger discovered that electrons orbit the nucleus of an atom Sep 14, 1914 Rutherford identified protons in the atomic nucleus Sep 14, 1932 James Chadwick first discovered neutrons, and isotopes were identified Sep 14, 1945 Glenn Seaburg identified lanthanides and actinides
