Introduction to Astronomy with Radioactivity

Abstract

The nineteenth century spawned various efforts to bring order into the elements encountered in nature. Among the most important was an inventory of the elements assembled by the Russian chemist Dimitri Mendeleyev in 1869, which grouped elements according to their chemical properties, their valences, as derived from the compounds they were able to form, at the same time sorting the elements by atomic weight. The genius of Mendeleyev lay in his confidence in these sorting principles, which enforced gaps in his table for expected but then unknown elements, and Mendeleyev was able to predict the physical and chemical properties of such elements-to-be-found. The tabular arrangement invented by Mendeleyev (Fig. 1.1) still is in use today, and is being populated at the high-mass end by the great experiments in heavy-ion collider laboratories to create the short-lived elements predicted to exist. The second half of the nineteenth century thus saw scientists being all-excited about chemistry and the fascinating discoveries one could make using Mendeleyev’s sorting principles. Note that this was some 30 years before sub-atomic particles and the atom were discovered. Today the existence of 112 elements is firmly established (the currently heaviest) element no. 112 was officially named Copernicium (Cn) in February 2010 by IUPAC, the international union of chemistry.