Development of the Periodic table

  • Johann Dobereiner

    The development of the periodic table begins with German chemist Johann Dobereiner. He grouped elements based on similarities
  • Law of Triads

    In 1829 Dobereiner proposed the Law of Triads. He proposed that the middle element in the triad had atomic weight that was the average of the other two.
  • 60 Elements

    By 1860 about 60 elements were known and a method was needed for organization.
  • First Periodic Table

    Alexandre Beguyer de Chancourtois created the first periodic table
  • John Newlands' new system

    John thought that the old system needed updating, so he arranged the 62 known elements in order of increasing atomic mass. After interval of eight elements similar physical or chemical properties reappeared
  • Mendeleev's proposle

    Dimitri Mendeleev propsed a new arrangment of the elements, by atomic weights and properites. This table contained 17 columns with two partial periods of seven elements each followed by two nearly complete periods.
  • Mendeleev's recised table

  • Lord Rayleigh and William Ramsey

    discovered inert gases
  • Lord Rayleigh and William Ramsey awarded nobel prize

  • Moseley's Periodic Law

    Discovery of the proton, he arranged the elements according to increasing atomic numbers and not atomic masses. The modern periodic table is based on Moseley's Periodic Law.
  • Glenn Seaborg discovery

    Seaborg discovered transuranium elements 94 to 102 and reconfigured the periodic table by placing the lanthanide/actinide series at the bottom of the table. In 1951 Seaborg was awarded the Nobel Prize.