URANIUM, NEPTUNIUM, PLUTONIUM AND AMERICIUM

Actinide Peroxides. Many peroxo compounds of thorium, protactinium, uranium, neptunium, plutonium, and americium are known (82,89). The crystal stmctures of a number of these have been deterrnined. Perhaps the best known are uranium peroxide dihydrate [1344-60-1/, UO 2H20, and, the uranium peroxide tetrahydrate [15737-4-5] UO 4H2O, which are formed when hydrogen peroxide is added to an acid solution of a uranyl salt. 

Reduction Reactions of Uranium, Neptunium, Plutonium and Americium in Aqueous Solutions" National Technical Information Service, U. S. Department of Commerce Springfield, Virginia, 1975. (b) Buxton, G. V. and... 

Uranium, Neptunium, Plutonium and Americium. Zit. bei G. N. Yakovlev and V. N. Kosyakov, The Chemistry of Americium. Report A/Conf. 15/P/2127. Proceedings, 2nd Intemat. Conference on the Peaceful Uses of Atomic Energy, Geneva 1958, Vol. 28, S. 383. 

Table 3. Formal reduction potentials (in volts) of uranium, neptunium, plutonium and americium for 1 M perchloric add solutions at 25 °C. (F. A. Cotton and G. Wilkinson Advanced Inorganic Chemistry. Interscience Publishers 1972)...

Torstenfelt B. 1986. Migration of the actinides, thorium, protactinium, uranium, neptunium, plutonium and americium in clay. Radiochem Acta 39 105-112. 

Sorption isotherms were also measured for sorption of selenium, technetium, tin, radium, uranium, neptunium, plutonium, and americium on the reference Mabton Interbed solids. The GR-1A groundwater composition was used in these experiments. Two temperatures (23°C 2°C and 60°C 1°C) were used, and both oxidizing and reducing conditions were used for each radionuclide. 

Newton, T. W and F. B. Baker Aqueous Oxidation-Reduction Reactions of Uranium, Neptunium, Plutonium, and Americium. In if. F. Gould (Ed.), Lanthanide/Actinide Chemistry, Advances in Chemistry Series, Vol. 71, p. 268. Washington American Chemical Society 1967. 

Aqueous Oxidation-Reduction Reactions of Uranium, Neptunium, Plutonium, and Americium... 

Isomorphism among compounds of the actinides is common and only a few examples need be given. The dioxides, MO2, of thorium, uranium, neptunium, plutonium and americium all have a fluorite lattice. The trihalides of the transuranic elements are isomorphous not only with the corresponding trihalides of actinium and uranium but also with those of the lanthanides. Isomorphism is also exhibited in many complex halides thus thorium, ura-... 

The RWMC assigned a high priority to the critical review of relevant chemical thermodynamic data of inorganic species and compounds of the actinides uranium, neptunium, plutonium and americium, as well as the fission product technetium. The first four books in this series on the chemical thermodynamics of uranium, americium, neptunium and plutonium, and technetium originated from this initiative. 

For the lighter actinide elements, such as uranium, neptunium, plutonium, and americium, the promotion energy of 5f —> 6d is smaller than that of 4f 5d transition in the lanthanides. Due to this smaller promotion energy, the chemical bonding is complicated in the lighter actinides and these elements take from 3+ to 7+ oxidation states. However, the heavier actinides beyond curium more closely resemble the lanthanides and the trivalent state becomes stable. In order to understand the chemistry of transuranium elements, one has to consider the relative energy of the valence orbitals and the relativistic effects on... 

M (VI) UO is the most stable oxidation state of uranium. Neptunium, plutonium and americium form MO ions in solution with the stability ordering being U > Pu > Np > Am. 

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