Doberiner He noted that similar elements often had relative atomic masses, grouping elements in ‘triads’.
DechancourtoisThe periodic law, however, appears to have been independently formulated by at least six people within one decade - De Chancourtois
Stanislao Cannizaro determined atomic weights for the elements known in the 1860s,
NewlandsThe eighth element, starting from a given one, is a kind of repetition of the first", which Newlands called the Law of Octavesnd arranged the table.
MeyerBoth Meyer and Mendeleev constructed periodic tables independently that are credited as being the basis of the modern table. Meyer was more impressed by the periodicity of physical properties, while Mendeleev was more interested in the chemical properties.
MendeleyevMendeleev constructed periodic tables independently that are credited as being the basis of the modern table. Mendeleev also published his periodic table & law in 1869, but he also forecast the properties of missing elements, and chemists began to appreciate it when
MoseleyLater, the table was reordered by Mosely according to atomic numbers (nuclear charge) rather than by weight, thereby modifying the Periodic Law.
SeaborgInto the 1930s the heaviest elements were being put up in the body of the periodic table, and Glenn Seaborg "plucked those out" while working with Fermi in Chicago, naming them the Actinide series, which later permitted proper placement of subsequently 'created' elements - the Transactinides, changing the periodic table yet again. These elements were shown separate from the main body of the table.