Dmitry Mendeleev, the man who brought law and order to chemistry

Dmitry Ivanovic Mendeleev was born in the Siberian provincial town of Tobolsk in February 1834. The youngest of 17 children, "Mityanka" as he was known to his friends, showed an early aptitude for physics, mathematics and history but disliked Latin.

When he was 13 his father died, yet despite the hardship this brought to the family, young Dmitry was able to complete his studies in mathematics and physics at the Central Pedagogical Institute in St. Peterburg (now Leningrad).

Even before being awarded the Institute's Gold Medal, Mendeleev had become fascinated by the possible relationships between the chemical properties of the elements and their physical structure.

After several years in Odessa and St. Petersburg, Mendeleev worked from 1859 to 1861 in Paris with the French chemist and physicist Henri Victor Regnault, and also with the German chemist Robert Bunsen, in Heidelberg.

It was during his stay in Germany in a laboratory he had arranged in his own home that the young chemist established the concept of critical temperature (above which a gas cannot be turned into liquid by pressure alone). And in nearby Karlsruhe he met the Italian chemist Stanislao Cannizzaro.

Mendeleev called Cannizzaro "my real predecessor... I observed immediately that the changes in the atomic weights which he proposed lent a new harmony to the groups suggested by Dumas," (professor of chemistry at the Sorbonne). "The idea of a possible periodicity in the properties of elements in relation to their ascending atomic weight occurred to me as of that moment."

By the age of thirty-three, Mendeleev had been named professor of general chemistry at the University of St. Petersburg, at that time Russia's most important chair in chemistry.

It was during this period that Mendeleev began piling one of his major works, "The Principles of Chemistry" (published in 1868). In writing this book he squarely faced the problem of how to present the elements and their relationships. Again and again he compared their properties in the hope of finding a key to the solution.

Describing his discovery, Mendeleev later said that in comparing elements and atomic weights, as he had noted them down on cards pinned to his laboratory wall, he had concluded that "the properties of elements depend in; periodic fashion on their atomic weights."

He added: "Even if I had some doubt concerning many obscure points, I had no doubt at all concerning the general character of the conclusion, since to admit that the relationships were purely coincidental was out of the question."

Mendeleev finally outlined his new thesis in a paper which he presented to a meeting of the Russian Chemical Society on March 1, 1869. Today his triumph is attested in every chemistry laboratory in the world: hanging in colour on the wall is his enduring handiwork the periodic Table of Elements.

Read also

Dmitry Mendeleev or the teachings of a prophet, UNESCO Courier, April-June 2019

Mendeleev’s periodic table, UNESCO Courier, January-March 2011

That chart on the laboratory wall, UNESCO Courier, June 1971