Dmitry Ivanovich Mendeleyev

Born in Siberia in 1834, he became one of the most influential chemists of the 19th century. He taught and wrote extensively, and his work helped organize chemistry into a clearer, more logical science.

His most famous achievement was formulating the periodic law and building a version of the periodic table that arranged elements by recurring properties. What made his approach remarkable was that he trusted the pattern enough to predict missing elements and correct some accepted measurements.

Beyond the periodic table, he worked on topics including liquids, solutions, and chemical education, and he remained an important scientific voice in Russia until his death in 1907.