Determination of the half-wave potential of nobelium

Electrochemistry / Flow electrolytic cell / Chemically modified electrode / Redox reaction Summary. We developed a new apparatus for the study of electrochemical properties of the heaviest elements. The apparatus is based on a flow electrolytic cell combined with column chromatography. Glassy-carbon fibers modified with Nafion perfluorinated cation-exchange resin are used as a working electrode as well as a cation-exchanger. The elution behavior of 139 Ce with the number of 10 10 atoms in 0.1 M ammonium α-hydroxyisobutyric acid solution from the column electrode was investigated at the applied potentials of 0.2-1.0 V versus the Ag/AgCl reference electrode in 1.0 M LiCl. It was found that 139 Ce 3+ is successfully oxidized to 139 Ce 4+ even with tracer concentration at around the redox potential determined by cyclic voltammetry for the macro amounts of Ce with 10 17 atoms (10 −3 M). The present oxidation reaction and separation of Ce 4+ was accomplished within a few minutes.

Section: Introductionmentioning

confidence: 99%

Development of an electrochemistry apparatus for the heaviest elements

Toyoshima¹,

Kasamatsu²,

Kitatsuji³

et al. 2008

“…Much work has been done over a number of years by FRANCOIS DAVID and coworkers [38,39,40,41] in the development of radiopolarography and radiocoulometry for the determination of E°'s in the actinide region from Am through Md. Also MEYER, MCDOWELL, DLTT-NER, SILVA, and TARRANT [42] made an early measurement by radiocoulometry of the half-wave potential for the reaction NO 2+ +2e~ = No(Hg)using 3.1 m 25S No. From these measurements, they obtained a value of -1.6 V for this reduction potential to the amalgam vs. the standard hydrogen potential.…”

Section: Heat Of Formationmentioning

confidence: 98%

Chemistry of the Heavy Actinides and Light Transactinides

Keller

1984

“…The formation constants they obtained are given in Table 8 and indicate for each anion, the complexing tendency of No 2+ is between that of Ca 2+ and Sr 2+ with Sr 2+ being slightly more favored. The standard potential for the reduction of No 2+ to No(Hg) was measured by a modified radiopolargraphic technique [91]. Usually, the half-wave potential is determined by measuring the distribution of an element between the mercury and aqueous phase as a function of applied voltage.…”

Section: Nobeliummentioning

confidence: 99%

Chemistry of the Elements Einsteinium through Element-105

Hulet

1983

All known chemical properties of each of the elements 99 (Es) through 105 are reviewed and these properties are correlated with the electronic structure expected for 5/and 6 d 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 this range of elements, the II -<· III oxidation potential decreases from ~ +1.5 to -1.5 volts. These observations lead to the conclusion that, in comparison with the analogous 4/electrons, the 5/ electrons in the latter part of the series are more tightly bound. Thus, there is a lowering of the 5/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 "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 6 ρ electrons by the 5/electrons. These relative ionic radii have been obtained from comparisons of the elution position in chromatographic separations.Lawrencium (Lr) completes the actinide series of elements with an electronic configuration of 5 / 14 7 s J 7 p. From Mendeleev's periodicity and Dirac-Fock calculations, the next group of elements is expected to be a ¿/-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.