Technikatörténeti szemle 25. (2001-02)
Papers of the Third International Conference on the History of Chemistry and Chemical Industry (Budapest, 2–4 July, 1999) – First Part - Tansjö, Levi: Mendelejev and the Nobel Prize in chemistry
LEVI TANSJÖ* MENDELEJEV AND THE NOBEL PRIZE IN CHEMISTRY The great Italian chemist Stanislao Cannizzaro used in the 1850s Avogardo's hypothesis from 1811 to determine atomic weights and molecular weights of volatile substances and laid by that a much more solid ground for the atomic weights than Berzelius had been able to do in the 1820s. Cannizzaro used Dulong-Petit's law to halve the atomic weights of Berzelius for the elements lithium, sodium, potassium and silver. Berzelius had supposed that the lowest oxides of these metals had the compositions LiO, NaO, KO and AgO but Cannizzaro showed that they had the compositions Li 2 0, Na 2 0, K 2 0 and Ag 2 0, i.e. the atomic weights for these metals had to be halved. That halving was important since it made it possible for Dmitri Mendelejev in St Petersburg and Lothar Meyer in Karlsruhe to discover a natural system for the elements. Mendelejev became In 1867 professor in chemistry at the University of St Petersburg. Since he couldn't find a good text-book for his students he decided to write one himself. He then wrote upon small pieces of paper the name and the atomic weight of the 63 then known elements. Their atomic weights had during the 1860s been ven/ carefully determined by the Belgian chemist Jean Servais Stas. When Mendelejev laid his 63 small pieces of paper in a long row after increasing atomic weight he saw that he could divide the row into smaller ones in such a way that related elements were collected in their own short row. In 1871 he presented his table in this form with the related elements in vertical groups with their atomicity or valence at the top. The system was named the Periodic Table of the elements and can be said to be one of the most fruitful systematizations of scientific knowledge ever made. There were in the table a number of empty places for elements which were not yet known but which according to Mendelejev sooner or later would be discovered and he predicted in some detail their physical and chemical properties. He called the unknown elements eka-boron, eka-aluminum, eka-silicon, eka-iodine, eka-mangane and eka-cesium, "eka" being a Sanskrit word meaning "the first one after". In 1875 Lecoq de Boisbaudran in Marseille discovered spectroscopically a new element which he named gallium after Gallia, the Latin name of France. He wrote to Mendelejev that he suspected that the new element was Mendelejev's eka-aluminum. Mendelejev answered that he also thought it was eka-aluminum but he also * University of Lund, P. O. Box 124, S-221 00 Lund, Sweden
