Trans-americium elements

The known oxidation states of the actinides are given in Table 20-3. With the exception of Th and Pa, the common oxidation state, and for trans-americium elements the dominant oxidation state, is +3, and the behavior is similar to the +3 lanthanides. Thorium and the other elements in the +4 state show resemblances to HfIv or Ceiv, whereas Pa and the elements in the +5 state show some resemblances to Tav. Exceptions to the latter statement are the dioxo ions MOJ for U, Np, Pu, and Am that are related to the M02+ ions in the +6 state. Redox potentials are given in Table 20-4. 

Ion-exchange procedures. Although ion-exchange procedures, both cationic and anionic, can be used to separate the actinide ions, they are best suited for small amounts of material. Since they have found most use in the separation of the trans-americium elements, these procedures are discussed below. 

The remaining elements, from Cf onward, have only the +3 state. The great similarity between the +3 ions of Am and the trans-americium elements has meant that the more conventional chemical operations successful for the separation of the previous actinide elements are inadequate and most of the separations require the highly selective procedures of ion-exchange discussed below solvent-extraction of the M3+ ions from 10-16M nitric acid by tributyl phosphate also gives reasonable separations. 

Fisher, N. S., P. Bjerregaard, and S. W. Fowler (1983), Interactions of Marine Plankton with Trans-uranic Elements. 1. Biokinetics of Neptunium, Plutonium, Americium, and Valifornium in Phytoplankton", Limnol. Oceanogr.28, 432. 

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 ... 

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