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Johann Dobereiner, triad system
he classified some elements into groups of three, which he called triads -
John Newlands, law of octaves
he suggested that elements be arranged in “octaves” because he noticed (after arranging the elements in order of increasing atomic mass) that certain properties repeated every 8th element. -
Lothar Meyer, orgainised by atomic mass
At the same time, he published his own table of the elements organized by increasing atomic mass. -
Dmitri Mendeleev, periodic table
he published a table of the elements organized by increasing atomic mass. -
Henry Moseley, rearranged the table
through his work with X-rays, he determined the actual nuclear charge (atomic number) of the elements*. He rearranged the elements in order of increasing atomic number. -
Glenn T. Seaborg, discovery of elements and rearrangment of element
After co-discovering 10 new elements, in 1944 he moved 14 elements out of the main body of the periodic table to their current location below the Lanthanide series. These became knownas the Actinide series.