Dmitry Ivanovich Mendeleyev
Dmitry Ivanovich Mendeleyev, (1834-1907). Russian chemist. His most important work was done on the classification of the elements into the periodic table. Elements were listed in increasing order of atomic weight and those with similar properties were grouped together. Mendeleyev left gaps for unknown elements, three of which were discovered within 20 years. He also worked on the properties of petroleum, the liquefaction of gases, and aeronautics.
