Man-made chemical elements

Fermi s pile turned out to be a plant which efficiently manufactured a new element in large quantities. This element is plutonium. It is a brand new man-made chemical element which fissons just as easily as U-235. The story of the birth of this synthetic element goes back to a day in May, 1940, when two men using Lawrence s cyclotron at Berkeley, California, bombarded uranium with neutron bullets. The two men were Edwin M. McMillan and Philip H. Abelson. After the bombardment of U-238 they detected traces of a new element, heavier than uranium. This new element, No. 93, was named neptunium by McMillan. It was a very difficult element to study, for its life span was very short. It threw out neutrons immediately and in a split second was no longer neptunium. 

The specific problems discussed in this book require the use of fundamental concepts and equations from various fields like kinetic theory of gases, kinetics of chemical reactions, thermodynamics and mass transfer. This chapter presents some basic relationships relevant to these problems. From the very beginning, the studies of gas-phase radiochemistry of heavy metallic elements have been largely motivated by the quest for new man-made chemical elements. It necessitated experimentation with very short-lived nuclides on one-atom-at-a-time basis. We will pay much attention to this direction of research. Accordingly, we will consider microscopic pictures (at the atomic and molecular level) of the processes underlying the experimental methods and concrete techniques, and follow individual histories of the molecules. 

In the case of man-made chemical elements (e.g., transactinides) a different type of problem arises, namely, the number of decays that can be observed is just not enough to measure out the exponential law because only a couple of like atoms are produced at a time. The determination of the decay constant - or, more directly, that of the mean-life (see Eq. (7.18)) - in such a case can be performed by the method explained in Sect. 19.3.4 of Chap. 19, Vol. 2. Some statistical background to this type of analysis is given in remark ( 33), Sect. 9.3.4, Chap. 9 in this volume. 

There is another problem with man-made chemical elements, namely that their isotopes are short lived too. This, together with the need for their identification, calls for fast separation methods. The Automated Rapid Chemistry Apparatus (ARCA) II S) tem and the Short-lived Isotopes Studied by the AKUFVE-technique (SISAK) equipment (both described in Sect. 59.2.2 of Chap. 59, Vol. 6, on Solvent Extraction and Ion Exchange in Radiochemistry ) are able to handle radionuclides with half-lives of -10 s and 1 s, respectively. 

---

See also in sourсe #XX -- [ , ]

---