Prof. Dr. , Johannes Gutenberg-Universität Mainz, Institut für Kernchemie
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Organizations:Johannes Gutenberg-Universität Mainz, Institut für Kernchemie
IYC Interests:Increase the public appreciation and understanding of chemistry
As an editor of Radiochimica Acta, I have prepared on the occasion of the International Year of Chemistry 2011 a special issue of Radiochimica Acta (see the web site given above) devoted to the man-made transuranium elements which, at this time, represent almost a quarter of the Periodic Table of the Elements. I have requested eminent scientists working in the field of the transuranium elements to write review articles on subjects as the syntheses of these elements, on their nuclear structure both from a theoretical and experimental point of view as well as on their chemical properties which are also of both theoretical and experimental interest.
The heaviest elements owe their stability to nuclear shell effects without which they would not exist. Shell closures for deformed nuclei at neutron numbers N = 152, N = 162, and N = 184 are well established. The location of the next sperical proton shell after the lead shell is still an open question. There is experimental evidence that the long favoured magic proton number Z = 114 is not the center of the pedicted "island of stability" and the search for the next spherical proton-shell closure continues. Equally exciting are the chemical properties of the heaviest elements: They depend increasingly with increasing nuclear charge on relativistic effects in the electron shell, giving them chemical properties that depend in a non-linear way from the properties of their lighter homologs in the Periodic Table. A most stiking example is element 114 (eka-lead) which, due to the relativistic contraction and energetic stabilization of its radially symmetric 7s and 7p1/2 valence-electron orbitals constituting a relativistic electron-shell closure, is gaseous in its elemental state.
After the discovery of the first transuranium element, neptunium, in 1940, seventy years have passed as we have written these reviews in 2010, and the intervening decades have seen great changes in science in general, and very large increases in understanding and new concepts of the transuranium elements in particular. The techniques of syntheses of the heaviest elements have changed dramatically and involve, at this time, powerful heavy-ion accelerators. The detection techniques have been improved in a very sophisticated way. They allow us to detect single atoms and to assign their mass and charge numbers unequivocally. New theoretical concepts have been devised and continuously improved and have provided guidance for new attempts. The aim of this special issue is to convey the essence of the ideas and the spirit of theory and experiment that characterizes the study of these elements. Heavy element discoveries, nuclear properties, nuclear structure, and nuclear synthetic reactions are covered as well as chemical properties and experimental techniques. I hope that this can serve as an up-to-date primer for the transuranium elements and as a convenient source of the key publications in this fascinating field of chemical research.