Mendeleyev also spelled Mendeleev
born Feb. 8, 1834, Tobolsk, Siberia, Russia
died Feb. 2, 1907, St. Petersburg
Russian chemist.
He taught at the University of St. Petersburg (1867–90) and later served as director of Russia's bureau of weights and measures. He made a fundamental contribution to chemistry by establishing in 1869 the principle of periodicity of the element s. His first periodic table was based on arranging the elements in ascending order of atomic weight and grouping them by similarity of properties. Mendeleyev's theory allowed him to predict the existence and atomic weights of several elements not discovered until years later.