Dmitry Mendeleyev
... 8, 1834, Mendeleyev made his most important contribution to chemistry, the discovery of the periodic chemical properties of the elements in 1869, when he was 35 and a teacher of chemical courses at St. ... Finished in 1854, Dmitry Mendeleyev became a science and math teacher. ... Mendeleyev served as professor of chemistry at the Saint Petersburg Technological Institute (1864-66) and at the University of Saint Petersburg (1867-90), a post that he resigned in protest against the administrations treatment of student petitions for reform. ... The systematization of ideas required for this book led Mendeleyev to formulate the periodic law in March 1869. ... In 1860, Mendeleyev discovered the concept of critical temperature and attended the first International Chemical Congress at Karlsruhe, where Stanislaw Cannizzaros views on atomic weights planted the seeds for the concept of the periodic table.