Trans-uranium elements

It should be noted that the ytterbium listed above was a mixture discovered in the mineral erbia by de Marignac in 1878 and not the neoytterbium/aldebaranium element renamed ytterbium that was foimd in the mineral ytterbia. The columbium was a mixture found in the mineral samarskite and was not the present day columbium/niobium. The ionium listed above was a mixture of terbium and gadolinium that was found in the mineral yttria and does not refer to °Th. Finally, the neptunium refers to material fovmd in niobium/tantalum minerals and does not refer to the 1940 discovery of the trans-uranium element produced via a neutron capture reaction on a uranium sample. 

In addition to these actinide(IV) compounds, the increasing stabihty of the - -3 oxidation state for the trans-uranium elements has recently led to the preparation of compounds of formula K[M(CgH8)2] where M=Np or Pu 31). In their chemical behavior these compounds axe similar to the corresponding lanthanide complexes vide infra) and their X-ray powder patterns suggest they have the same structure. They appear to be much more ionic than their -f4 analogues. 

McMillan, E. M., The trans-uranium elements early history, Les Prix... 

The discovery of fermium (also einsteinium) was not the result of very carefully planned experiments, as in the cases of the other trans uranium elements, bill fermiuni and einsteinium were found in Ihe debris of an atomic weapon lest in the Pacific in November 1952. Researchers, using the Oak Ridge High Flux Isotope Reactor (HFIR) which produced 3.2-hour " Fm. determined ihe magnetic moment of the atomic ground state of the neutral fermium atom with a modified atomic beam magnetic resonance... 

The periodic table prepared by Mendeleev became a target for scientists and elements as the blank spaces in his table were quickly discovered. Of great importance also was the indication of the presence of the trans-uranium elements in Mendeleev s studies. 

Nuclear chemistry (radiochemistry) has now become a large and very important branch of science. Over four hundred radioactive isotopes have been made in the laboratory, whereas only about three hundred stable isotopes have been detected in nature. Three elements —technetium (43), astatine (85), and promethium (61), as well as some trans-uranium elements, seem not to occur in nature, and are available only as products of artificial transmutation. The use of radioactive isotopes as tracers has become a valuable technique in scientific and medical research. The controlled release of nuclear energy promises to lead us into a new world, in which the achievement of man is no longer limited by the supply of energy available to him. 

Manufacture of the Trans-Uranium Elements. The first transuranium element to be made was a neptunium isotope, Np . This isotope was made by E. M. McMillan and P. H. Abelson, in 1940, by bombarding uranium with high-speed deuterons ... 

Plutonium and the four heavier trans-uranium elements whose existence have been reported, americium, curium, berkelium, and californium, were discovered by Professor G. T. Seaborg and his collaborators at the University of California in Berkeley. Americium has been made as the isotope Am by the following reactions ... 

Trans-uranium elements Transition metals Gold... 

The mutual separation of actinide elements and the selective isolation of useful actinides from fission products are indispensable for the nuclear fuel cycle and have become important subjects of investigation for the development of advanced nuclear fuel reprocessing and TRU (TRans Uranium elements) waste management [1], A variety of research concerning the separation chemistry of actinides has so far been accumulated [2]. There are, however, only a few theoretical studies on actinides in solution[3-5]. Schreckenbach et a), discussed the stability of uranyl (VI) tetrahydroxide [UO,(OH) ] [3] and Spencer and co-workers calculated the optimized structures of some uranyl and plutonyl hydrates [AcO, nH,0 (Ac = U, Pu and n = 4,5,6)] [4],... 

C5. Cefola, M., The ide of micro- and ultramicrochemistiy in the isolation of the first trans-uranium element Plutonium. Microchem. J. 2, 205-217 (1958). 

The terrestrial occurrence of Ac, Pa, U, and Th is due to the half-lives of the isotopes 235U, 238U and 232Th which are sufficiently long to have enabled the species to persist since genesis. They are the sources of actinium and protactinium formed in the decay series and found in uranium and thorium ores. The half-lives of the most stable isotopes of the trans-uranium elements are such that any primordial amounts of these elements appear to have disappeared long ago. However, neptunium and plutonium have been isolated in traces from uranium13 minerals in which they are formed continuously by neutron reactions such as... 

This chapter discusses production of radionuclides for beneficial use in science, medicine and technology. The nuclear fundamentals for the production processes have been given in Chapters 11 to 14. The formation of radionuclides is discussed in several Chapters e.g. cosmogenic reactions leading to the formation of short-lived radionuclides in nature (Ch. S and 10) thermonuclear reactions leading to the formation of long-lived radioactivity in the universe (Ch. 17) the synthesis of trans-uranium elements (Ch. 16 and 19-21). The production and isolation of separated fission products is treated separately (Ch. 19-21). This chapter discusses aspects of fundamental importance to the production of radionuclides by a variety of methods. Initially the principles are reviewed and, subsequently, the most advanced techniques for investigating short-lived radionuclides are described. 

The most recent spate of elemental discoveries is ako based on technological developments, involving the production and harnessing of beams of pure atoms or pure elementary particles such as neutrons. These particles can be fired at each other with great precision to achieve nuclear fusion reactions and to thereby create new elements with extremely high atomic numbers. The initiator of this field was the American chemist Glenn Seaborg, who first synthesized plutonium in 1943 and went on to head research teams that were responsible for the synthesk of many more trans-uranium elements. 

The naming of the later trans-uranium elements is a separate story in itself, complete with nationahstic controversies and, in some cases, acrimonious disputes... 

Another curious case concerns the German chemist Otto Hahn, whose name was unofficially given to the element hahnium only to be removed later and changed to the name dubnium after the place where several trans-uranium elements were synthesized. Meanwhile, an element has been named after Hahn s onetime colleague Lise Meitner. To many observers, this is a just move since Hahn had been awarded the Nobel Prize for the discovery of nuclear fission while Meitner, who had participated in many of the crucial steps in the work, was denied the prize. To others, it represents an excess of political correctness. 

The material balance in the NFC for a generic case can be sununarized, as detailed later, based on seminar material from the European Nuclear Euel Management. Starting with 20,000 tons of ore that contains 1% uranium that after milling is reduced to 230 tons of uranium ore conceutrates (of which 195 tons consist of uranium). This is converted to 288 tons of UF and after enrichment one part is enriched to 4% 2 U (35 tons UFg containing 24 tons uranium) and the rest (254 tons UFg containing 171 tons uranium) is in the tails. The enriched uranium is converted into 27 tons of UO2 from which electricity (7000 million kWh) can be produced in the reactor. The spent fuel will contain 23 tons of uranium (-0.8% U), -240 kg of plutonium, -720 kg of fission products, and some trans-uranium elements. 

Subsequent commentators have concurred not only with Nyholm s identification of a post-war renaissance of inorganic chemistry, but also with his causal factors. Some also cite the war itself, and the research it generated into nuclear chemistry and the trans-uranium elements, as another important contributor ... 

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