Dimitri Mendeleev was born in Tobolsk, Siberia, and was the youngest of a family of seventeen. After his father died, his mother, determined that Dimitri should have the best possible education, moved the family to St. Petersburg. In 1856 Mendeleev obtained a master’s degree in chemistry and then taught at the University of St. Petersburg. In 1867 he was appointed professor of inorganic chemistry.

While giving his course of lectures, he felt the need for a new textbook, and he began writing what was to become a famous and widely used textbook, Principles of Chemistry. He realized that the order and system that was then becoming apparent in organic chemistry was lacking in inorganic chemistry, and in attempting to remedy this situation, he was led to formulate the periodic table in 1869.

To consider that the properties of the elements were in some way related to their atomic masses was an imaginative idea, since the structures of atoms were unknown at the time. Moreover, to bring certain elements into the correct group from the point of view of their chemical properties, he was bold enough to reverse the order of some pairs of elements and to predict that their atomic masses were incorrect. Some of these predictions were correct, but others were not, because we now know that the fundamental basis of the periodic table is atomic number rather than atomic mass. Also, to keep elements in the correct groups according to their chemical properties, he left gaps in his table, making the prediction that they would be filled by elements that were still undiscovered at that time. From the trends that he observed among the properties of related elements, he predicted the properties of these undiscovered elements.

At first the periodic table attracted little attention. Then, when his predictions concerning undiscovered elements were fulfilled in considerable detail by the successive discoveries of gallium (1874), scandium (1879), and germanium (1885), chemists began to realize that in the periodic table they had a tool of the greatest value. From that time on Mendeleev was recognized as one of the foremost scientists of the day.

Mendeleev was a versatile genius who was interested in many fields of science, both pure and applied. He worked on many problems associated with Russia’s natural resources, such as coal, salt, and petroleum, and in 1876 he visited the United States to study the Pennsylvania oil fields. He invented an accurate barometer; he made an ascent in a balloon to study a total eclipse of the sun; and he was interested in the possibility of air travel.

As a professor at the University of St. Petersburg, Mendeleev was unavoidably involved in the political turmoil that affected all nineteenth-century Russia. Although in the middle of the century universities had been left comparatively free to carry out their research and teaching as they saw fit, the government came to suspect that academic freedom encouraged political unrest. Many repressive measures were taken against the universities, and the students reacted with demonstrations and riots. The universities were frequently closed for long periods, and many students were exiled to Siberia. In 1890 Mendeleev resigned from the university because of the government’s oppressive treatment of students and the lack of academic freedom. Fortunately, he still had friends at the Czar’s court, and he was appointed director of the Bureau of Weights and Measures, where he continued to carry out important research.

Mendeleev was a colorful character as well as a genius. A characteristic always noticed in the portraits of Mendeleev is his enormous head of hair. Biographers say that he only had it cut once a year in the spring and that he would not deviate from this custom even when he had an audience with the Czar.

Bob