Chemical neptunium, plutonium

Plutonium - the atomic number is. 94 and the chemical symbol is Pu. The name derives from the planet Pluto, (the Roman god of the underworld). Pluto was selected because it is the next planet in the solar system beyond the planet Neptime and the element plutonium is the next element in the period table beyond neptunium. Plutonium was first synthesized in 1940 by American chemists Glenn T. Seaborg, Edwin M. McMillan, Joseph W. Kennedy and Arthur C. Wahl in the nuclear reaction U( H, 2n) Np = P => Pu. The longest half-life associated with this unstable element is 80 million year Pu. 

As mentioned in the Introduction, the actinyl ions are not stable under all chemical conditions. Plutonium can coexist in solution in several oxidation states, the stability of which often depends strongly on acidity (26). As a result, great care must be taken to obtain pure solutions of PuOl(27). On the other hand, the neptunyl ion NpO is the most stable form of neptunium in aqueous solution. It is noteworthy that the exchange between the oxygen atoms of PuO and H20 is very slow (ti/2 > 10 h) (25), whereas it is quite fast (h/2 2.2 s) in the case of NpO. ... 

This article presents a general discussion of actinide metallurgy, including advanced methods such as levitation melting and chemical vapor-phase reactions. A section on purification of actinide metals by a variety of techniques is included. Finally, an element-by-element discussion is given of the most satisfactory metallurgical preparation for each individual element actinium (included for completeness even though not an actinide element), thorium, protactinium, uranium, neptunium, plutonium, americium, curium, berkelium, californium, and einsteinium. 

Lemire, R. J., Fuger, J. et al. 2001. Chemical Thermodynamics of Neptunium Plutonium. Elsevier, Amsterdam. 

Guillaumont, R., Fanghanel, T., Fuger, J., Grenthe, I., Neck, V. 2003. Update on the Chemical Thermodynamics of Uranium, Neptunium, Plutonium, Americium and Technetium. Elsevier Science, North Holland, Amsterdam, p. 919. 

Chemical components in the waste solutions potentially could affect radioelement solubility and sorption reactions, and thus enhance or reduce radionuclide transport. The effects of 12 chemical components on the solubility and sorption of cobalt, strontium, neptunium, plutonium, and americium were studied to... 

Especially interesting in a discussion of radionuclide speciation is the behaviour of the transuranium elements neptunium, plutonium, americium and curium. These form part of the actinide series of elements which resemble the lanthanides in that electrons are progressively added to the 5f instead of the 4f orbital electron shell. The effective shielding of these 5f electrons is less than for the 4f electrons of the lanthanides and the differences in energy between adjacent shells is also smaller, with the result that the actinide elements tend to display more complex chemical properties than the lanthanides, especially in relation to their oxidation-reduction behaviour (Bagnall, 1972). The effect is especially noticeable in the case of uranium, neptunium and plutonium, the last of which has the unique feature that four oxidation states Pum, Pu, Puv and Pu are... 

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. 

Separation of Actinides from the Samples of Irradiated Nuclear Fuels. For the purpose of chemical measurements of burnup and other parameters such as accumulation of transuranium nuclides in irradiated nuclear fuels, an ion-exchange method has been developed to separate systematically the transuranium elements and some fission products selected for burnup monitors (16) Anion exchange was used in hydrochloric acid media to separate the groups of uranium, of neptunium and plutonium, and of the transplutonium elements. Then, cation and anion exchange are combined and applied to each of those groups for further separation and purification. Uranium, neptunium, plutonium, americium and curium can be separated quantitatively and systematically from a spent fuel specimen, as well as cesium and neodymium fission products. 

The tables in this section present thermodynamic data for uranium, americium, technecium, neptunium, plutonium, and auxiliary species. Also presented are chemical analyses of some groundwaters from uranium deposits and granites. 

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. 

Nobelium is a member of the actinide series of elements. The ground state electron configuration is assumed to be (Rn)5fl47s2, by analogy with the equivalent lanthanide element ytterbium ([Kr]4fl46s2) there has never been enough nobelium made to experimentally verify the electronic configuration. Unlike the other actinide elements and the lanthanide elements, nobelium is most stable in solution as the dipositive cation No ". Consequently its chemistry resembles that of the much less chemically stable dipositive lanthanide cations or the common chemistry of the alkaline earth elements. When oxidized to No, nobelium follows the well-estabhshed chemistry of the stable, tripositive rare earth elements and of the other tripositive actinide elements (e.g., americium and curium), see also Actinium Berkelium Einsteinium Fermium Lawrencium Mendele-vium Neptunium Plutonium Protactinium Ruthereordium Thorium Uranium. 

Micro techniques have been very useful in chemical studies of the actinide elements, and particularly so for the study of the halides. Historically, micro methods were required because of the very small amounts of the synthetic actinides originally available for experiment. However, even when large amounts of neptunium, plutonium, and other actinide elements became available, micro methods were found to offer many advantages, and they have therefore continued to be of great service to this day. W. H. Zachariasen was able to obtain and interpret X-ray diffraction patterns on samples of the order of a few micrograms and the... 

In the determination of transuranium elements (or nuclides), the most important step is separation of the elements from the sample matrix. Differences in redox properties are used for the separation of the first four elements in the series (neptunium, plutonium, americium, curium). Since the higher members exist primarily in the same oxidation state (III), separation by ion-exchange chromatography is commonly used. The lighter transuranic elements can be determined by common chemical methods, and trace amounts are usually determined by radiometric methods such as a-spectrometry. 

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... 

Neptunium, plutonium, americium, and curium To improve the sensitivity, neptunium, plutonium, americium, and curium were measured after chemical separation. For americium and curium, chemical separation and radiometric measurement were the only alternative due to the short half-lives, a-spectrometry is more sensitive than ICP-MS. 

Chemicals of normal reagent-grade purity suffice for the separation of analytes that do not occur in nature there should be no important impact on the analyses of samples of neptunium, plutonium, americium, or curium, provided reagent volumes are kept small so that mass is not introduced into the final samples. For all other analytes, reagents that... 

GuiUaumont R, Fanghanel T, Fuger J, Grenthe I, Neck V, Palmer DA and Rand MH 2003 Chemical Thermodynamics Vol. 5 Update on the Chemical Thermodynamics of Uranium, Neptunium, Plutonium, Americium, and Technetium. F. J. Mompean and M. Illemassene and C. Domenech-Orti and K. Ben Said,Editors . Elsevier, Amsterdam. 

Pu, Zr(+Nb), and Ce and iTithenlum complexes. Neptunium, plutonium, and cerium are made less extractable by reduction to lower oxidation states. Favorable separation of tiranlum from the other elements may be achieved by control.of the nitric acid and saltlng-out agent concentrations. Free halogens are extracted. These elements may be eliminated from solution prior to uranliim extraction. The halogens also combine chemically with a number of solvents eg,. 

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