Dmitry Ivanovich Mendeleev is a famous Russian chemist. He is best known for his development of the properties of the chemical elements of the periodic table. This table shows that property elements change periodically when they are ordered atomic weight. Mendeleev was born in 1834 in Tobolsk, Siberia. He studied chemistry at the University of St. Petersburg and in 1859 he was sent to study at the University of Heidelberg. Mendeleev returns to St. Petersburg and became a professor of chemistry at a technical institute in 1863. He became a professor of general chemistry at the University of St. Petersburg in 1866. Mendeleev was a well-known teacher, and, because there was not a good textbook on chemistry at that time, He wrote in two volumes "Principles of Chemistry", which became a classic Textbook on Chemistry. In this book, Mendeleev tried to classify elements according to their chemical properties. In 1869, he published his first version of his periodic table of elements. In 1871, he published an improved version of the periodic table in which He left spaces for elements that were not known at that time. His table and theories were later confirmed when three predicted elements: gallium, germanium, and scandium were discovered. Mendeleev investigated chemical solution theories. He found that the best proportions of alcohol and water in vodka are 40%. He also investigated the thermal expansion of liquids and the nature of oil. In 1893, he became director of the Bureau of Weights and Measures in St. Petersburg and held this post until his death in 1907.
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