Einsteinium oxides

Edison storage battery, 406 Einstein, Albert, 121 Einsteinium, oxidation number, 414 Elastic collision, 6 Electrical nature of atoms, 236 Electrical phenomena, 74 Electrical properties of condensed phases, 78... 

Americium, californium, and einsteinium oxides have been reduced by lanthanum metal, whereas thorium has been used as the reductant metal to prepare actinium, plutonium, and curium metals from their respective oxides. Berkelimn metal could also be prepared by Th reduction of Bk02 or Bk203, but the quantity of berkelium oxide available for reduction at one time has not been large enough to produce other than thin foils by this technique. Such a form of product metal can be very difficult to handle in subsequent experimentation. The rate and yield of Am from the reduction at 1525 K of americium dioxide with lanthanum metal are given in Fig. 2. 

The best characterized einsteinium oxide is the cubic (C-type) sesquioxide, prepared by calcining nanograms of a nitrate salt and rapidly analyzing the product by electron diffraction (Haire and Baybarz 1973). A monoclinic form of the sesquioxide was observed when thin films of einsteinram metal were oxidized in oxygen-containing atmospheres at temperatures of 800 1000°C (the direct oxidation of other actinide metals can also yield the monoclinic form of their sesquioxides at temperatures lower than that required for transformation of their C- to the B- forms). This low temperature for the monoelinic form of einsteinium sesquioxide is therefore not comparable to the established transition temperatures reported for the other actinide sesquioxides. The... 

Extrapolations for the einsteinium oxide transitions based on the lanthanide oxide and transplutonium oxide systems would suggest the C- to B-type transition for ES2O3 to be on the order of 1400°C, and the B- to A-type transition to be at least 1650°C. Lattice parameters for the three forms of einsteinium oxide are given in table 25. 

The chemical properties of fermium are very similar to those of other triva-lent actinide series elements, californium and einsteinium. The element s oxidation state -1-3 is its only known oxidation state. 

The references given in Table I are those describing the preparation of a given compound the reference may or may not contain information on the behavior of the compound with time Note that the compounds have been synthesized in different oxidation states and different crystal structures where possible Not shown in the table are einsteinium, berkelium, and californium phosphates which have also been prepared and are being studied at present (11) ... 

Bulk-Phase Compounds Some of our results in the studies of the bulk-phase compounds have been published (3-7) These studies have shown that oxidation state is preserved for these actinides in either a or fT decay Trivalent einsteinium will transmute to trivalent berkelium which transmutes to trivalent californium It has also been observed that divalent einsteinium yields divalent californium. It is interesting to note in this latter case that it has not yet been possible to synthesize divalent berkelium in the bulk phase Berkelium(II) has not been observed in our aged einsteinium(II) compounds either, but it would be logical to assume it has been produced there. Our inability to observe Bk(II) could be related to weak absorption intensities and/or interference by absorption bands of einsteinium(II) or... 

In all samples prepared in which the oxidation state of the einsteinium differed from that of the host cation, over a time period of several years, only californium(III) has been identified as arising from the samples that initially contained einsteinium (III), and only californium(II) has been observed in samples that originally contained einsteinium(II). Even when the parent was in a host of differing oxidation state, the progeny species maintained the oxidation state of the parent ... 

Polarographic studies gave no evidence for the existence of the bivalent oxidation states of selected actinides in acetonitrile solution. Only one wave corresponding to reduction of americium(iii) or curium(iii) to the zero-valent state was observed and experiments with berkelium(iii) and einsteinium(iii) failed to give conclusive results because of rapid radiolysis of the acetonitrile solution. A study of the electrochemical reduction of americium, thulium, erbium, samarium, and europium showed that the elements did assume the bivalent state with the actinide bivalent cations having a smaller stability than the lanthanides. The half-wave potential of nobelium was found to be —1.6 V versus the standard hydrogen electrode for the reaction... 

The double-double effect has been considered in review articles17-20) lectures21-24) and also in some monographs 10,25 27). In these publications, however, emphasis is placed on the double-double effect observed within the lanthanide series. The purpose of this paper is to review the literature data on the double-double effect observed in actinides. In contrast to lanthanides, in the case of actinides, the double-double effect cannot be observed in its full pattern because of the following reasons (i) the elements heavier than einsteinium are still hardly available, (ii) the stable oxidation state changes along the series, and (iii) there are only few data on stability constants or extraction coefficients for... 

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. 

Mendelevium — (Dmitri Mendeleev [1834-1907]), Md at. wt. (258) at. no. 101 m.p. 827°C valence +2, +3. Mendelevium, the ninth transuranium element of the actinide series to be discovered, was first identified by Ghiorso, Harvey, Choppin, Thompson, and Seaborg early in 1955 as a result of the bombardment of the isotope Es with helium ions in the Berkeley 60-inch cyclotron. The isotope produced was Md, which has a half-life of 78 min. This first identification was notable in that Md was synthesized on a one-atom-at-a-time basis. Nineteen isotopes and isomers are now recognized. Md has a half-life of 51.5 days. This isotope has been produced by the bombardment of an isotope of einsteinium with ions of helium. It now appears possible that eventually enough Md can be made so that some of its physical properties can be determined. Md has been used to elucidate some of the chemical properties of mendelevium in aqueous solution. Experiments seem to show that the element possesses a moderately stable dipositive (II) oxidation state in addition to the tripositive (III) oxidation state, which is characteristic of actinide elements. 

Einsteinium compounds the element shows oxidation states of -1-2 and -1-3, the -1-3 state being that of a typical... 

---