Volatilization behavior of transactinides from metal surfaces and melts (thermochemical calculation)

Volatilization properties of elements with the atomic numbers Z=104 to 116 are determined on the basis of empirical relations. These empirical correlations are deduced from the analysis of thermochemical data of metallic elements in the periodic table and their relations to the material constant: Structure specific connections are shown to exist between the electron densities at the 'Wigner-Seitz' cell borders of metals and the specific surface energies of solid metals with hexagonal, cubic face-centred, cubic body-centred and rhombohedral lattices. Analogously, structure specific relations can be found between the standard enthalpies of the gaseous monoatomic metals and their surface energies. Linear correlations with exceptionally high correlation coefficients are observed between the standard sublimation enthalpies of isotypic metals in the dimeric state and the surface energies. Volatilization properties are deduced for the transactinides on the basis of these established relations, applying a predicted structure and further empirical correlations. These volatilization properties are in detail: the standard enthalpies of the gaseous monomers; the standard sublimation enthalpies of the dimers; the standard dissociation enthalpies of the dimers; the standard enthalpies of adsorption on metal surfaces; the volatilization enthalpies from molten metals, and the standard formation enthalpies of hetero binuclear intermetallic molecules. Thermochemical constants required for the calculation of the intermetallic interactions are determined using the Miedema model. The closed systematic approach facilitate: the assessment of the calculated data considering the agreement with known rules of metal chemistry, trends in the 7th row and along the groups of the periodic table, the coherence of the data, and the action of closed shell effects in the electron configurations. From the obtained data conclusions are possible regarding the design of volatilization experiments, which serve for the chemical separation and characterization of some of these elements. (author)