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Period: to
Johann Dobereiner
He developed groups of 3 elements with similar properties -
Period: to
John Newlands
He arranged the known elements in order of atomic weights & observed similarities between some elements -
Period: to
Lothar Meyer
He developed an early version of the periodic table, with 28 elements organized by valence -
Period: to
Dmitri Mendeleev
He produced a a table based on atomic weights but arranged periodically with elements with similar properties under each other. His Periodic Table included the 66 known elements organised by atomic weights. -
Period: to
Henry Moseley
He determined the atomic number of each of the elements and modified the 'Periodic Law'. -
Period: to
Glenn Seaborg
He synthesised transuranic elements (the elements after uranium in the periodic table)