Mendeleev , Dmitri Ivanovich

(1834–1907) Russian chemist

Mendeleev was the youngest child of a large family living in Tobolsk, Siberia. His father was a local school teacher whose career was ended by blindness and to support the family his mother ran a glass factory. Mendeleev learned some science from a political refugee who had married one of his sisters. His father died in 1847, and soon after his mother's factory was destroyed by fire. She left Tobolsk with Mendeleev, determined that her last son should receive a good education, and placed him at the Pedagogic Institute of St. Petersburg only ten weeks before her death. He later studied in France under Henri Regnault and in Heidelberg with Robert Bunsen and Gustav Kirchhoff.

While abroad Mendeleev attended the famous conference at Karlsruhe in 1860 which did so much to settle the question of atomic weights. He returned to Russia shortly after and in a short time had completed his doctorate, written a textbook, and married. In 1866 he was elected to the chair of chemistry at St. Petersburg University where he remained until his retirement in 1890. His textbook The Principles of Chemistry was published between 1868 and 1870.

In 1869 Mendeleev published his classic paper On the Relation of the Properties to the Atomic Weights of Elements, which brought order and understanding to this confused subject. His first major proposal was his claim that the only way of classifying the elements is by their atomic weights. Optical, magnetic, and electrical properties vary with the state the body is in at any particular moment; other properties, such as valence, yield conflicting results. When the elements are arranged in order of increasing atomic weight, Mendeleev found that they show a distinct periodicity of their properties. Arranging them in rows of increasing atomc weights produced columns of similar elements.

The table did not at first receive universal acceptance, but its value became apparent during the following 20 years. Through it Mendeleev was able to spot those elements that had been assigned incorrect atomic weights. Thus he suggested that the atomic weights of gold and tellurium must be wrong. There were three missing elements in his table, and he was able to predict their existence, valences, and certain physical properties. The three were eventually discovered – ‘eka-aluminum’ (gallium, Paul Lecoq de Boisbaudran, 1875), ‘eka-boron’ (scandium, Per Cleve, 1879), and ‘eka-silicon’ (germanium, Clemens Winkler, 1885).

Mendeleev became the most famous Russian scientist of his day and received numerous medals and prizes although not, surprisingly, the Nobel Prize (in 1906 it was awarded to Ferdinand Moissan by one vote). Element 101 was namedmendelevium in his honor.