The arrangement of the chemical elements in the periodic table highlights resemblances in chemical properties, which reflect the elements' electronic structure. For the heaviest elements, however, deviations in the periodicity of chemical properties are expected: electrons in orbitals with a high probability density near the nucleus are accelerated by the large nuclear charges to relativistic velocities, which increase their binding energies and cause orbital contraction. This leads to more efficient screening of the nuclear charge and corresponding destabilization of the outer d and f orbitals: it is these changes that can give rise to unexpected chemical properties. The synthesis of increasingly heavy elements, now including that of elements 114, 116 and 118, allows the investigation of this effect, provided sufficiently long-lived isotopes for chemical characterization are available. In the case of elements 104 and 105, for example, relativistic effects interrupt characteristic trends in the chemical properties of the elements constituting the corresponding columns of the periodic table, whereas element 106 behaves in accordance with the expected periodicity. Here we report the chemical separation and characterization of six atoms of element 107 (bohrium, Bh), in the form of its oxychloride. We find that this compound is less volatile than the oxychlorides of the lighter elements of group VII, thus confirming relativistic calculations that predict the behaviour of bohrium, like that of element 106, to coincide with that expected on the basis of its position in the periodic table.

In the presence of polyborates (detected by (11)B-NMR) the formation of a weak Eu(III) borate complex (lg β11 ~ 2, estimated) was observed by time-resolved laser-induced fluorescence spectroscopy (TRLFS). This complex is a precursor for the formation of a solid Eu(III) borate species. The formation of this solid in solution was investigated by TRLFS as a function of the total boron concentration: the lower the total boron concentration, the slower is the solid formation. The solid Eu(III) borate was characterized by IR spectroscopy, powder XRD and solid-state TRLFS. The determination of the europium to boron ratio portends the existence of pentaborate units in the amorphous solid.

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With only a few atoms of seaborgium (Sg, element 106), in the form of volatile SgO(2)Cl(2), it was possible to determine the sublimation enthalpy of this compound using gas chromatography. Furthermore, it was demonstrated that in Group 6 Sg is chemically more similar to W than to Mo.

Seaborgium / Group 6 elements / Oxide hydroxides / Reaction gas chromatographySummary. Seaborgium (Sg; element 106) was studied in comparison with tungsten in the O 2 -H 2 O (g) /SiO 2(s) -system using high temperature on-line isothermal gas chromatography. The 21-s nuclide 266 Sg was produced in the 248 Cm + 22 Ne reaction at a beam energy of 119 MeV. The reaction products were continuously transported by a He(MoO 3 )-jet to the chromatography apparatus HITGAS. Group 6 element oxide hydroxide molecules volatile at temperatures above 1000 K were formed at 1325 K by adding humid oxygen as reactive gas. 266 Sg was unambiguously detected after gas chromatographic separation by measuring 266 Sg-262 Rf mother-daughter α-sf correlations. The experimental results demonstrate the volatility of Sg in humid oxygen, presumably as Sg oxide hydroxide, a behavior typical for both U(VI) and the group 6 elements.