development of the periodic table

  • law of trials prposed

    In 1829 Dobereiner proposed the Law of Triads: Middle element in the triad had atomic weight that was the average of the other two members.
  • first 60 elements

    in 1860 the first 60 elements found
  • the first periodic table had been published

    the first periodic table was made by proffesor Alexandre Beguyer de Chancourtois
  • new arrangment of periodic table perposed

    Dimitri Mendeleev proposed arranging elements by atomic weights
  • 17 group table with eight columns

    In 1871 Mendeleev revised the 17-group table with eight columns (the eighth group consisted of transition elements).
  • discoverd the inert gases

    In 1895 Rayleigh reported the discovery of a new gaseous element named argon.
  • elements xrayed

    Soon after Rutherford's landmark experiment of discovering the proton in 1911, Henry Moseley subjected known elements to x-rays.
  • last major change to the periodic table

    Starting with plutonium in 1940, Seaborg discovered transuranium elements 94 to 102 and reconfigured the periodic table by placing the lanthanide/actinide series at the bottom of the table.
  • seaborg got a nobel prize

    In 1951 Seaborg was awarded the Nobel Prize in chemistry and element 106 was later named seaborgium (Sg) in his honor.