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He was the first person to try and classify the elements by properties and he did so by putting them into four groups: metals, non-metal, gases, and earths. -
He was the first to recognize that the elements fall into patterns where their properties repeat at consistent intervals when listed in the order of increasing atomic weight. He was also the first to assign atomic numbers. -
He created his own periodic table listing the elements known at the time by ascending atomic mass as well as arranged by how reactive they are. -
He proposed organizing Mendeleev's table by basing it on physical properties based on atomic number instead of atomic mass.