Chemical properties of the heavier actinides and transactinides
The chemical properties of each of the elements 99 (Es) through 105 are reviewed and their properties correlated with the electronic structure expected for 5f and 6d elements. A major feature of the heavier actinides, which differentiates them from the comparable lanthanides, is the increasing stability of the divalent oxidation state with increasing atomic number. The divalent oxidation state first becomes observable in the anhydrous halides of californium and increases in stability through the series to nobelium, where this valency becomes predominant in aqueous solution. In comparison with the analogous 4f electrons, the 5f electrons in the latter part of the series are more tightly bound. Thus, there is a lowering of the 5f energy levels with respect to the Fermi level as the atomic number increases. The metallic state of the heavier actinides has not been investigated except from the viewpoint of the relative volatility among members of the series. In aqueous solutions, ions of these elements behave as a normal trivalent actinides and lanthanides (except for nobelium). Their ionic radii decrease with increasing nuclear charge which is moderated because of increased screening of the outer 6p electrons by the 5f electrons. The actinide series of elements is completed with the element lawrencium (Lr) in which the electronic configuration is 5f/sup 14/7s/sup 2/7p. From Mendeleev's periodicity and Dirac-Fock calculations, the next group of elements is expected to be a d-transition series corresponding to the elements Hf through Hg. The chemical properties of elements 104 and 105 only have been studied and they indeed appear to show the properties expected of eka-Hf and eka-Ta. However, their nuclear lifetimes are so short and so few atoms can be produced that a rich variety of chemical information is probably unobtainable.
- Research Organization:
- Lawrence Livermore National Lab., CA (USA)
- DOE Contract Number:
- W-7405-ENG-48
- OSTI ID:
- 5678433
- Report Number(s):
- UCRL-85944; CONF-810948-3; ON: DE82005701; TRN: 82-008141
- Resource Relation:
- Conference: Actinides-1981 conference, Pacific Grove, CA, USA, 10 Sep 1981
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
EINSTEINIUM
CHEMICAL PROPERTIES
ELECTRONIC STRUCTURE
FERMIUM
LAWRENCIUM
MENDELEVIUM
NOBELIUM
ACTINIDE COMPOUNDS
AQUEOUS SOLUTIONS
VOLATILITY
ACTINIDES
DISPERSIONS
ELEMENTS
METALS
MIXTURES
SOLUTIONS
TRANSPLUTONIUM ELEMENTS
TRANSURANIUM ELEMENTS
400702* - Radiochemistry & Nuclear Chemistry- Properties of Radioactive Materials