[en] The history of discovery of mendelevium is described, its isotopes with mass numbers 252 and 254-258 are listed, and their nuclear properties are given. Isolation and purification of mendelevium, and characteristic curves of its elution are discussed. The most interesting property of the element is its capacity of transforming into Md(2) under the action of various reducers. The behaviour of Es, Fm and Md in indicator amounts upon reduction is compared

[en] The report of a stable, monovalent, cesium-like ion of mendelevium is in conflict with recent estimates of the relative stability of Md⁺, based on electrochemical systematics of the actinide series. To clarify this situation, experiments using controlled-potential electrolysis were undertaken to study the over-all reduction mechanism of Md³⁺ to the amalgam. Half-wave amalgamation potentials were measured by radiocoulometry in the presence of weak (acetate) and strong (citrate) complexing agents. The half-wave potentials with respect to the normal hydrogen electrode were found to be -1.49 +- 0.01 V in acetate and -1.60 +- 0.01 V in citrate solutions. The results showed that Md behaved analogously to Fm, which has been shown to undergo electrode reduction in two steps, 3+ → 2+ and 2+ → 0. The half-wave potentials observed for Md are believed to be characteristic of the reduction 2+ → 0. Further, the shift in the half-wave potential of mendelevium caused by a strong complexing agent is too large to be explained by reduction of a cesium-like, monovalent ion. (author)

[en] Short note

[en] Short note

[en] The possible existence of a monovalent ion of mendelevium has been examined further by radiopolarography. Experiments were conducted in several aqueous media with ²⁴¹Am, ²⁴⁹Cf, ²⁵⁴Es, sup(255,256)Fm and ²⁵⁶Md tracers. Half-wave amalgamation potentials of Md in tetramethylammonium perchlorate and in LiCl were identical within the experimental errors at - 1.755 +- 0.005 V vs the saturated calomel electrode, in good agreement with an earlier study by radiocoulometry in an ammonium acetate medium. No shift in the half-wave potential of Md was observed due to NH₄⁺ or Cl^- ions; hence, these ions do not act as complexing agents for Md ions present during electrochemical reductions. The shift in the half-wave potential observed in the presence of citrate as a complexing agent was characteristic of the reduction process Md²⁺ → Md⁰(Hg). In noncomplexing media, the slope of the logarithmically transformed wave of Md was approximately 30 mV, consistent only with a reversible, two-electron reduction process. All of the results provide evidence for electrochemical reduction of the Md²⁺ ion only and disprove the existence of an intermediate Md⁺ ion in aqueous solution with properties like those of Cs⁺, Ag⁺ or Cu⁺. (author)

[en] Preparation of volatile β-diketonates of californium, einsteinium, fermium and mendelevium by extraction method and by the reaction of heterophase exchange of ligands (L) in systems: metal compound (condensed phase)-β-diketone (vapour), is described. Thermochromatographic behaviour of voilatile β-diketonates is studied. Hexafluoroacetylacetone, trifluoroacetylacetone, acetylacetone, dipivaloylmethane, tenoyltrifluoroacetone are used as L. It is shown that in the series of the actinides studied not the nature of the central ion, but the nature of L produces the determining effect on the volatility of the complexes. 12 refs.; 3 figs.; 1 tab

[en] Short note. 2 refs.; 2 figs.; 1 tab

[en] Short note.4 refs

[en] Short note. 3 refs.; 2 tabs

[en] Short note. 1 tab