Dmitri Mendeleev

Dmitri Ivanovich Mendeleev (February 8, 1834 – February 2, 1907) was a Russian chemist and inventor who fundamentally transformed the study of chemistry. Born in Siberia, Mendeleev studied chemistry in Russia and abroad, eventually becoming a professor at St. Petersburg University. In 1869, he created the periodic table of elements by organizing elements by atomic weight and leaving gaps for undiscovered elements. His boldness in predicting the properties of missing elements—gallium, scandium, and germanium—which were later discovered with properties matching his predictions, vindicated his system and established him as a scientific visionary. Beyond chemistry, Mendeleev was a prolific inventor and thinker who contributed to various fields including the development of Russian industry. He was passionate about education reform and served as a mentor to younger scientists. Though his full periodic table was later refined with the discovery of noble gases and reorganized by atomic number rather than weight, Mendeleev's fundamental framework remains the foundation of chemistry education worldwide, and his name is honored in element 101, mendelevium.