Dmitri Ivanovich Mendeleev (1834-1907)

Dmitri Ivanovich Mendeleyev (also written Mendeleev) was a Russian chemist born in Siberia who created the first version of the periodic table of elements. His father, a teacher forced into early retirement by blindness, died when Mendeleyev was 13. Mendeleyev’s mother was left to support their large family, and took her son to St Petersburg to enrol him in his father’s old college, the Main Pedagogical Institute. After teacher training, he was sent to teach in a secondary school in Odessa.

Mendeleyev soon returned to St Petersburg, where he studied at St Petersburg University, receiving a master’s degree in 1856. He continued his chemical research at the university while teaching chemistry at various institutions in the city. He spent the years 1859-60 on a state stipend in western Europe, mostly at Heidelberg.

In 1860, Mendeleyev attended the Karlsruhe Congress - the first international conference on chemistry. The delegates, predominantly European chemists, discussed the need for standardised chemical notation and nomenclature, and attempted to reach agreement on a system of atomic weights.

Mendeleyev received an appointment to the chair of chemistry at the St Petersburg Technological Institute in 1864, but soon returned to the university as a professor of chemical technology. In 1867 he moved to the chair of general chemistry at the university.

Mendeleyev developed the periodic system of the elements while he was writing a chemistry textbook, Principles of Chemistry. He introduced his periodic table in 1869, though he was not the first to propose that the elements might be periodic - John Newlands and Lothar Meyer had both suggested versions of a system where elements could be arranged by atomic weight and according to shared properties. However, Mendeleyev’s breakthrough was his willingness to overlook the discrepancies in the atomic weights of the elements when placed in the right order, and to leave gaps in the system for several undiscovered elements. His intellectual boldness was vindicated some 40 years later when Henry Moseley showed that the order of the elements was determined by the number of protons they contained (their so-called atomic number) rather than their atomic weight.

Apart from the periodic table, Mendeleyev was also interested in the interaction between molecules and he discovered the ‘critical point’ (the conditions beyond which a gas cannot be liquefied by pressure) independently of Thomas Andrews, the scientist traditionally credited with the discovery.

In 1880 fellow academics proposed him for the chair of chemical technology at the Imperial Academy of Sciences, but, controversially, his candidacy was opposed by a number of influential individuals and ultimately rejected. He resigned from his university chair ten years later. Mendeleyev did much consulting work in a variety of sectors, including the petroleum and agriculture industries. He was subsequently made Director of the Bureau of Weights and Measures in 1893, a post he still occupied at the time of his death.