Dmitri Mendeleev — Chemist and Architect of the Periodic Table

Dmitri Ivanovich Mendeleev was born on 8 February 1834 (27 January Old Style) in Tobolsk, Siberia, the youngest of a large family. His father, a schoolteacher, went blind and died soon after; his mother ran a glassworks and then personally took the teenage Dmitri across Russia to St. Petersburg to secure him an education.

Location: Tobolsk, Russia

Mendeleev sent to the Russian Chemical Society his paper "On the Relationship of the Properties of the Elements to their Atomic Weights," arranging the 63 known elements by increasing atomic weight and showing that properties recurred periodically. He left gaps where no known element fit, reasoning that undiscovered elements belonged there — a prediction no other systematizer had dared to make.

Location: Saint Petersburg, Russia

Between 1868 and 1870 Mendeleev published his two-volume textbook The Principles of Chemistry, written first and foremost for his own students. The book organized chemistry around the periodic law, spread his system through translations into English, German, and French, and remained a standard text for decades.

Location: Saint Petersburg, Russia

French chemist Paul-Emile Lecoq de Boisbaudran discovered gallium — matching almost exactly the density, atomic weight, and chemistry Mendeleev had predicted for his "eka-aluminium." When the discoverer's first measurements disagreed with the prediction, Mendeleev wrote from St. Petersburg to say the numbers were wrong; re-measurement proved him right.

Location: Paris, France

The discovery of scandium in 1879 (matching eka-boron) and germanium in 1886 (matching eka-silicon) filled the remaining predicted gaps. The triple vindication convinced chemists worldwide that the periodic law was a law of nature rather than a convenient table, and Mendeleev's priority over rival systematizers such as Lothar Meyer was generally recognized — the two shared the Davy Medal in 1882.

Location: Freiberg, Germany

Mendeleev was appointed director of Russia's newly organized Bureau of Weights and Measures in 1893, where he worked on metrological standardization and pushed for a decimal system of Russian measurement. He also argued for a state standard of alcohol content and championed science-based policy in a rapidly industrializing empire.

Location: Saint Petersburg, Russia

The Royal Society awarded Mendeleev its Copley Medal in 1905, its highest honor, for his discovery of the periodic law. He had retired from his professorship in 1890 after supporting a student protest, and had flown in a balloon in 1887 to observe a solar eclipse — his celebrity in Russia approached that of Tolstoy.

Location: London, United Kingdom

Mendeleev died on 2 February 1907 (20 January Old Style), weeks before his 73rd birthday. In 1955 the newly synthesized element 101 was named mendelevium, one of only two elements named for an individual at the time of naming.

Location: Saint Petersburg, Russia