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The high nuclear charges of the heaviest elements influence their electronic structure and hence their chemical properties. [1][2][3][4][5] The experimental results so far obtained for the heaviest chemically investigated elements reveal that seaborgium, [6,7] bohrium, [8] and hassium [9] behave as typical representatives of the corresponding Group 6, 7, and 8 of the periodic table. Apparently, relativistic effects do not introduce a perceptible destabilization of the highest oxidation states of these elements in the chemical environments they have been studied in. An even stronger increase of relativistic effects is predicted for the transactinides of Groups 12-18. [1][2][3] Element 112, a representative of Group 12 of the periodic table, has a predicted closed-shell electronic ground-state configuration of [Rn]5f 14 6d 10 7s 2 , rendering this element one of the key elements regarding relativistic effects in the electronic structure. [3,5,10] Recently, our gas chromatography experiments with only two observed atoms of element 112 revealed evidence for a metallic adsorption interaction with the stationary gold surface. [11] Here we present new experimental results with an increased number of observed atoms that confirm these observations and improve their statistical significance. From the complete data set, thermochemical and physical data are deduced for element 112 and compared to the corresponding properties of its homologues in Group 12: Zn, Cd, and Hg. The increased stabilization of the atomic state of element 112 reveals a further enhancement of the relativistic effects with increasing atomic number Z in Group 12.For element 112 a noble-metallic character was predicted from empirical extrapolations. [12,13] Relativistic atomic calculations revealed a contraction of the spherical 7s orbitals, leading to the prediction of an enhanced stability of the elemental atomic state for element 112. Accordingly, a noblegas-like behavior was postulated. [14] Modern calculation methods confirmed a stronger binding of the 7s orbitals. [3] However, the spin-orbit coupling of the 6d orbitals is predicted to lead to an electronic ground state configuration with a 6d 5/2 orbital that is similar energetically and spatially to the 7s orbital, indicating that element 112 could be a noble transition metal [5,15] or even a semiconductor. [16] Based on these strongly differing predictions, it is decisive for experimentalists to be able to distinguish in chemical experiments whether element 112 behaves more as a noble metal or as a noble gas. Therefore, investigation of gas adsorption properties of element 112 on metal surfaces has been suggested. [17] In such studies the energy content of the adsorption bond between element 112 and the metallic stationary phase, the standard adsorption enthalpy at zero surface coverage (DH ads Au ), is determined. This quantity differentiates between metal-bond formation and weak van der Waals physisorption interaction. The semiempirical macroscopic adsorption model based on the Miedema approach ...

The mass of an atom incorporates all its constituents and their interactions. The difference between the mass of an atom and the sum of its building blocks (the binding energy) is a manifestation of Einstein's famous relation E = mc(2). The binding energy determines the energy available for nuclear reactions and decays (and thus the creation of elements by stellar nucleosynthesis), and holds the key to the fundamental question of how heavy the elements can be. Superheavy elements have been observed in challenging production experiments, but our present knowledge of the binding energy of these nuclides is based only on the detection of their decay products. The reconstruction from extended decay chains introduces uncertainties that render the interpretation difficult. Here we report direct mass measurements of trans-uranium nuclides. Located at the farthest tip of the actinide species on the proton number-neutron number diagram, these nuclides represent the gateway to the predicted island of stability. In particular, we have determined the mass values of (252-254)No (atomic number 102) with the Penning trap mass spectrometer SHIPTRAP. The uncertainties are of the order of 10 keV/c(2) (representing a relative precision of 0.05 p.p.m.), despite minute production rates of less than one atom per second. Our experiments advance direct mass measurements by ten atomic numbers with no loss in accuracy, and provide reliable anchor points en route to the island of stability.