Tracers xenon isotopes

Argon-40 [7440-37-1] is created by the decay of potassium-40. The various isotopes of radon, all having short half-Hves, are formed by the radioactive decay of radium, actinium, and thorium. Krypton and xenon are products of uranium and plutonium fission, and appreciable quantities of both are evolved during the reprocessing of spent fuel elements from nuclear reactors (qv) (see Radioactive tracers). 

Since the discovery of the first noble gas compound, Xe PtF (Bartlett, 1962), a number of compounds of krypton, xenon, and radon have been prepared. Xenon has been shown to have a very rich chemistry, encompassing simple fluorides, XeF2> XeF, and XeF oxides, XeO and XeO oxyf luorides, XeOF2> XeOF, and Xe02 2 perxenates perchlorates fluorosulfates and many adducts with Lewis acids and bases (Bartlett and Sladky, 1973). Krypton compounds are less stable than xenon compounds, hence only about a dozen have been prepared KrF and derivatives of KrF2> such as KrF+SbF, KrF+VF, and KrF+Ta2F11. The chemistry of radon has been studied by radioactive tracer methods, since there are no stable isotopes of this element, and it has been deduced that radon also forms a difluoride and several complex salts. In this paper, some of the methods of preparation and properties of radon compounds are described. For further information concerning the chemistry, the reader is referred to a recent review (Stein, 1983). 

The name comes from the Greek xenon, meaning stranger. Xenon was discovered by William Ramsay (1852-1916) and Morris W. Travers (1872-1961) in 1898 as part of their search for a noble gas between helium and argon. It is present as a trace element in atmospheric air. It is the heaviest of the noble gases. It is used commercially in specialty lamps and lasers, as well as in sophisticated laboratory equipment such as bubble chambers and as a radioactive isotope used as a tracer. 

Radon lies on the diagonal of the Periodic Table between the true metals and nonmetals and is classed as a metalloid. As the heaviest and most metallic of the naturally occurring noble gases, radon has the lowest ionization energy of the group (1030 kJ mol ) consequently, it is expected to be the most reactive. The chemistry of radon is, however, less extensive than the chemistries of krypton and xenon and is rendered considerably more difficult because no stable isotopes of this element exist. The inherent radiation hazard that accompanies the intense radioactivity of radon requires tracer level experimentation. Nevertheless, evidence has been obtained that radon forms a difluoride and several complex salts. 

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