Mendeleyev, Dmitri Ivanovich (1834–1907)

Russian chemist who framed the periodic law in chemistry in 1869, which states that the chemical properties of the elements depend on their relative atomic masses. This law is the basis of the periodic table of the elements, in which the elements are arranged by atomic number and organized by their related groups.

Mendeleyev was the first chemist to understand that all elements are related members of a single ordered system. From his table he predicted the properties of elements then unknown, of which three (gallium, scandium, and germanium) were discovered in his lifetime. Meanwhile Lothar Meyer in Germany presented a similar but independent classification of the elements.

Mendeleyev was born in Tobol'sk, Siberia, and studied at St Petersburg and in Germany at Heidelberg. He became professor at the Technical Institute in St Petersburg 1864. But in 1890, for supporting a student rebellion, he was retired from the university and became controller of the Bureau for Weights and Measures.

Mendeleyev was convinced that the future held great possibilities for human flight, and in 1887 he made an ascent in a balloon to observe an eclipse of the Sun.

His textbook Principles of Chemistry 1868–70 was widely adopted.