Mendeleyev's periodic table, 1869.

Dmitry Mendeleyev (1834-1907) was the Rusian chemist who formulated the Periodic Table of the elements, which grouped the elements according to their atomic structure and chemical properties. His work enabled chemists to identify 'families' of elements with similar chemical and physical properties and has influenced ideas in organic chemistry ever since. In 1955 a new element, atomic number 101, was named mendelevium (Md) in his honour.