Mendeleyev, Dmitri Ivanovich 1834-1907
Russian chemist

He was born in Tobolsk, Siberia, and studied at St Petersburg and Heidelberg, Germany, where he collaborated briefly with Robert Wilhelm Bunsen and investigated the behaviour of gases, formulating the idea of critical temperature. He was appointed professor at the St Petersburg Technical Institute in 1863 and at the University of St Petersburg in 1866. In 1869 he tabulated the elements in ascending order of their atomic weight and found that chemically similar elements tended to fall into the same columns. Several attempts had already been made to group the elements by their chemical properties and to relate chemical behaviour to atomic weight but Mendeleyev's great achievement was to realize that certain elements still had to be discovered and to leave gaps in the table where he predicted they would fall. At first the periodic table was largely rejected by the scientific world, but as each new element that was subsequently discovered fitted into it perfectly, scepticism turned to enthusiasm. However, the underlying reason for the periodicity of the elements remained unexplained until the structure of the atom came to be understood. Mendeleyev continued to refine the table for the next 20 years, meanwhile continuing his work on gases, studying solutions and taking up aeronautical research (he made a solo ascent in a balloon in 1887). The transuranic element mendelevium (atomic number 101) is named in his honour.

Bibliography: Mendeleyev, Daniel Q Posin, Mendeleyev: The Story of a Great Scientist (1948)