Dmitri Mendeleev

Dmitri Ivanovich Mendeleev (1834-1907) [ MEN -de-LAY-ev), Russian chemist, discovered that ordering the then (1869) known chemical elements, sixty-three in number, according to their increasing atomic weights, revealed a repeated cycle of recurrence, every seven elements, of their chemical and physical properties &mdash; i.e., the properties recurred as functions of the elements' atomic weights &mdash; a discovery that permitted him to predict subsequently experimentally established revised values for the atomic weights of several elements and, importantly, the subsequently confirmed existence of yet undiscovered elements with atomic weights and properties required to fill in missing elements in an otherwise consistent periodicity in his ordering scheme, a scheme which chemists subsequently referred to as the periodic table of the chemical elements (Mendeleev and Jensen 2002).

Introduction
When, within a few years of the announcement of Mendeleev's ordering scheme in 1869, chemists discovered three new chemical elements (gallium, scandium, germanium) that accorded with his prediction of their atomic weights and properties, and after confirmation of his proposed revisions of the atomic weights for certain specified elements suggested by his periodic table, Mendeleev's contemporaries worldwide eventually came to recognize his discovery as a natural law of chemistry transcending taxonomy, and as a fundamental contribution to the understanding of the nature of physical reality, setting the stage for his successors, notably the 20th century Danish physicist, Niels Bohr, to formulate a theory of atomic structure and its regularities that explained Mendeleev's periodic law and the deviations to it discovered with the ever expanding discovery of new elements, in particular, the rare earth elements (Brush 1996).

As the theory of evolution ineluctably evokes the name of Charles Darwin, and the theory of relativity the name of Albert Einstein, the periodic law of the chemical elements evokes the name of Dmitri Mendeleev.

Mendeleev's life and work and 'world' he lived in
As the 17th and last child of his parents, among the 14 who lived long enough to receive a Christian name, Dmitri Mendeleev entered the world on February 8, 1834, in a city founded in 1587, Tobolsk, located in west-central Russia, in the heart of Western Siberia, southeast of Moscow (2385 km 1482 mi, by train), south of the confluence of two rivers, the Irtysh and Ob rivers, nearer the confluence of the Irtysh and Tobol rivers, in the bend of the Irtysh, the city founded in 1587 CE. ....