The periodic table provides a classification of the chemical properties of the elements. But for the heaviest elements, the transactinides, this role of the periodic table reaches its limits because increasingly strong relativistic effects on the valence electron shells can induce deviations from known trends in chemical properties. In the case of the first two transactinides, elements 104 and 105, relativistic effects do indeed influence their chemical properties, whereas elements 106 and 107 both behave as expected from their position within the periodic table. Here we report the chemical separation and characterization of only seven detected atoms of element 108 (hassium, Hs), which were generated as isotopes (269)Hs (refs 8, 9) and (270)Hs (ref. 10) in the fusion reaction between (26)Mg and (248)Cm. The hassium atoms are immediately oxidized to a highly volatile oxide, presumably HsO(4), for which we determine an enthalpy of adsorption on our detector surface that is comparable to the adsorption enthalpy determined under identical conditions for the osmium oxide OsO(4). These results provide evidence that the chemical properties of hassium and its lighter homologue osmium are similar, thus confirming that hassium exhibits properties as expected from its position in group 8 of the periodic table.
Independent verification of the production of element 114 in the reaction of 244-MeV ;{48}Ca with ;{242}Pu is presented. Two chains of time- and position-correlated decays have been assigned to ;{286}114 and ;{287}114. The observed decay modes, half-lives, and decay energies agree with published results. The measured cross sections at a center-of-target energy of 244 MeV for the ;{242}Pu(;{48}Ca,3-4n);{287,286}114 reactions were 1.4_{-1.2};{+3.2} pb each, which are lower than the reported values.
Spectroscopy of Element 115 Decay Chains
Superheavy Element Flerovium (Element 114) Is a Volatile MetalAccess to the published version may require subscription. Superheavy Element Flerovium (Element 114) is a Volatile MetalAlexander Yakushev †, , Jacklyn M. ABSTRACT: The electron shell structure of superheavy elements, i.e., elements with atomic number Z ≥ 104, is influenced by strong relativistic effects caused by the high Z. Early atomic calculations on element 112 (copernicium, Cn) and element 114 (flerovium, Fl) having closed and quasiclosed electron shell configurations of 6d 10 7s 2 and 6d 10 7s 2 7p 1/2 , respectively, predicted them to be noble gas-like due to very strong relativistic effects on the 7s and 7p 1/2 valence orbitals. Recent fully relativistic calculations studying Cn and Fl in different environments suggest them to be less reactive compared to their lighter homologs in the groups, but still exhibiting a metallic character. Experimental gassolid chromatography studies on Cn have, indeed, revealed a metal-metal bond formation with Au. In contrast to this, for Fl, the formation of a weak bond upon physisorption on a Au surface was inferred from first experiments. Here, we report on a gas-solid chromatography study of the adsorption of Fl on a Au surface. Fl was produced in the nuclear fusion reaction 244 Pu( 48 Ca, 3-4n) 288,289 Fl and was isolated in-flight from the primary 48 Ca beam in a physical recoil separator. The adsorption behavior of Fl, its nuclear α-decay product Cn, their lighter homologs in groups 14 and 12, i.e., Pb and Hg, and the noble gas Rn were studied simultaneously by isothermal gas chromatography and thermochromatography. Two Fl atoms were detected. They adsorbed on a Au surface at room temperature in the first, isothermal part, but not as readily as Pb and Hg. The observed adsorption behavior of Fl points to a higher inertness compared to its nearest homolog in the group, Pb. However, the measured lower limit for the adsorption enthalpy of Fl on a Au surface points to the formation of a metal-metal bond of Fl with Au. Fl is the least reactive element in the group, but still a metal.
Element 104 / Rutherfordium / Liquid-liquid extraction / Transactinide chemistry / KurchatoviumAbstract Liquid-liquid extractions of element 104 (Rf), Zr, Nb, Hf, Th, and Pu(IV) were conducted using tributylphosphate (TBP) in benzene. Initial studies were conducted using 95 Zr and 95 Nb. The effect of TBP, HCl, chloride, and hydrogen ion concentrations on Zr and Nb extraction was examined. Based on the results from these experiments, it was decided to examine Rf extraction into 0.25 M TBP in benzene as a function of HCl, chloride, and hydrogen ion concentrations between 8 and 12 M. Studies of these extraction conditions were carried out using 95 Zr, 169 Hf, 228 Th, 238 Pu, and 26, Rf. The 65-second 261 Rf was produced via the 248 Cm( 18 0,5n) reaction at the 88-Inch Cyclotron at Lawrence Berkeley Laboratory. The results show that extraction for these elements increases or remains high as a function of HCl concentration. However, in the experiments in which the chloride and hydrogen ion were varied, Rf extraction differed from that of the group 4 elements and behaved more like Pu(IV).
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