33 No. 5
This special issue of Radiochimica Acta, published in celebration of the International Year of Chemistry 2011, is devoted to the man-made transuranium elements which, at this time, represent almost a quarter of the Periodic Table of the Elements. The journal’s editors asked eminent scientists working in the field of transuranium elements to write review articles on subjects such as the syntheses of the heaviest elements, their nuclear structure both from a theoretical and an 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 and N=162 are well established. The location of the next spherical shell after the lead shell is still an open question. There is experimental evidence that the long-favored magic proton number Z=114 is not the center of the predicted “island of stability,” which means that the search for the next spherical proton-shell closure continues. Equally exciting are the chemical properties of the heaviest elements: They exhibit increasing nuclear charge on relativistic effects in the electron shell, giving them chemical properties that deviate in a non-linear way from the properties of their lighter homologues in the periodic table. A most striking example is element 114 (eka-lead) which, due to the relativistic contraction and energetic stabilization of its radially symmetric 7s2 and 7p1/22 valence-electron orbitals constituting a relativistic electron-shell closure, is gaseous in its elemental state.
The first transuranium element, neptunium was discovered in 1940. 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 used to synthesize 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. It covers heavy-element discoveries, nuclear properties, nuclear structure and nuclear synthesis reactions, chemical properties, and experimental techniques. It is intended to 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.
last modified 12 September 2011.
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