Engraving of Dmitri Ivanovich Mendeleev (1834- 1907), Russian chemist. Mendeleev was the youngest of 14 children. Initially an indifferent student, he left college at the top of his class. After attending the great Karlsruhe Congress, Mendeleev worked to unite the ideas of atomic weights and valence. From this, he developed the first true periodic table of the elements. This contained some gaps, as only 63 elements were known at the time. As new elements were discovered to have the properties predicted by the table, Mendeleev became world-famous. Honours were showered upon him, but in later life he was castigated by his own government for his liberal political views.