Superheavy element

Berkeley group reported their inability to reproduce the original observation (Gregorich et al., Eur. J. Phys. A IS, 633 (2003)). A subsequent investigation (Gilchriese et al., 2003) revealed the original data had been fabricated by one individual, who was later connected to similar instances of fraud at Darmstadt in the work with elements 110 and 112 mentioned above. From these episodes, one learns that science works, fraud will be found, and the traditional method of independent confirmation of important findings is reaffirmed. 

Up to 1970, it was thought that the practical limit of the periodic table would be reached at about element 108. By extrapolating the experimental data on heavy-element half-lives, we concluded that the half-lives of the longest-lived isotopes of the heavy elements beyond about element 108 would be so short ( 10-6 s) due to spontaneous fission decay that we could not produce and study them (Fig. 15.10). However, in the late 1960s and early 1970s, nuclear theorists, using techniques developed by Vilen Stmtinsky and Wladyslaw Swiatecki, predicted 

We now know these predictions were wrong, in part. While we believe there are a group of superheavy nuclei whose half-lives are relatively long compared to lower Z elements, we do not believe they form an island of stability. Rather, we picture them as a continuation of the peninsula of known nuclei (Fig. 15.1 lb). We also believe that their half-lives are short compared to geologic time scales. Therefore, they do not exist in nature. The most stable of the superheavy nuclei, those with Z = 112, N 184, are predicted to decay by a-particle emission with half-lives of 20 days. 

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Table 11 illustrates the known closed proton and neutron shells and the predicted closed nuclear shells (shown in parentheses) that might be important in stabilising the superheavy elements. Included by way of analogy are the long-known closed electron shells observed in the buildup of the electronic stmcture of atoms. These correspond to the noble gases, and the extra stabiUty of these closed shells is reflected in the relatively small chemical reactivity of these elements. The predicted (in parentheses) closed electronic stmctures occur at Z = 118 and Z = 168. 

G. Hermann, Superheavy Elements, International Review of Science, Inorganic Chemisty, Series 2, Vol. 8, Butterworths, London, and University Park Press, Baltimore, Md., 1975 G. T. Seaborg and W. Loveland, Contemp. Physics 28, 233 (1987). 

A further group of elements, the transuranium elements, has been synthesized by artificial nuclear reactions in the period from 1940 onwards their relation to the periodic table is discussed fully in Chapter 31 and need not be repeated here. Perhaps even more striking today are the predictions, as yet unverified, for the properties of the currently non-existent superheavy elements.Elements up to lawrencium (Z = 103) are actinides (5f) and the 6d transition series starts with element 104. So far only elements 104-112 have been synthesized, ) and, because there is as yet no agreement on trivial names for some of these elements (see pp. 1280-1), they are here referred to by their atomic numbers. A systematic naming scheme was approved by lUPAC in 1977 but is not widely used by researchers in the field. It involves the use of three-letter symbols derived directly from the atomic number by using the... 

B. Fricke, Superheavy elements, Structure and Bonding 21, 89 (1975). A full account of the predicted stabilities and chemical properties of elements with atomic numbers in the range Z = 104- 184. 

Since the radioactive half-lives of the known transuranium elements and their resistance to spontaneous fission decrease with increase in atomic number, the outlook for the synthesis of further elements might appear increasingly bleak. However, theoretical calculations of nuclear stabilities, based on the concept of closed nucleon shells (p. 13) suggest the existence of an island of stability around Z= 114 and N= 184. Attention has therefore been directed towards the synthesis of element 114 (a congenor of Pb in Group 14 and adjacent superheavy elements, by bombardment of heavy nuclides with a wide range of heavy ions, but so far without success. 

F. Bosh, A. ElGoresy, W. Kratschmer, B. Martin, B. PovH, R. Nobiling, K. Traxel and D. Schwalm, Z Physik A280, 39-44 (1977) see also C. J. Sparks, S. Raman, H. L. Takel, R. V. Gentry and M. O. Krause, Phys. Rev. Letters 38, 205-8 (1977), for retraction of their earlier claim to have detected naturally occurring primordial superheavy elements. 

Frenking G, Cremer D (1990) The Chemistry of the Nobles Gas Elements Helium, Neon, and Argon - Experimental Facts and Theoretical Predictions. 73 17-96 Frey M (1998) Nickel-Iron Hydrogenases Structural and Functional Properties. 90 97-126 Fricke B (1975) Superheavy Elements. 21 89-144... 

The chemistry of superheavy elements has made some considerable progress in the last decade [457]. As the recently synthesized elements with nuclear charge 112 (eka-Hg), 114 (eka-Pb) and 118 (eka-Rn) are predicted to be chemically quite inert [458], experiments on these elements focus on adsorption studies on metal surfaces like gold [459]. DFT calculations predict that the equilibrium adsorption temperature for element 112 is predicted 100 °C below that of Hg, and the reactivity of element 112 is expected to be somewhere between those of Hg and Rn [460, 461]. This is somewhat in contradiction to recent experiments [459], and DFT may not be able to simulate accurately the physisorption of element 112 on gold. More accurate wavefunction based methods are needed to clarify this situation. Similar experiments are planned for element 114. 

Fricke, B. (1975) Superheavy elements a prediction of their chemical and physical properties. Structureel Bonding, 21,89-144. Eliav, E., Kaldor, U., Schwerdtfeger, P., Hess, B. and Ishikawa, Y. (1994) The Ground State Electron Configuration of... 

Schwerdtfeger, P. (2003) Relativistic Pseudopotentials, in Theoretical Chemistry and Physics of Heavy and Superheavy Elements, Vol. 11 (eds U. Kaldor and S. Wilson), Progress in Theoretical Chemistry and Physics, Kluwer, Dordrecht, pp. 399—438. in references therein. 

Seth, M., Cooke, F., Pehssier, M., Heully J.-L. and Schwerdtfeger, P. (1998) The Chemistry of the Superheavy Elements II. The Stability of High Oxidation States in Group 11 Elements. Relativistic Coupled Cluster Calculations for the Fluorides of Cu, Ag, Au and Element 111. Journal of Chemical Physics, 109, 3935—3943. 

Hancock, R.D., Bartolotti, L.J. and Kaltsoyannis, N. (2006) Density Functional Theory-Based Prediction of Some Aqueous-Phase Chemistry of Superheavy Element 111. Roentgenium (I) Is the Softest Metal Ion. Inorganic Chemistry, 45, 10780-10785. 

Schadel, M. (2003) The Chemistry of Superheavy Elements, Kluwer Academic. Dordrecht. 

Pershina, V., Bastug, T., Sarpe-Tudoran, C., Anton, J. and Fricke, B. (2004) Predictions of adsorption behaviour of the superheavy element 112. Nuclear Physics... 

Superheated steam dryers, 9 138-139 Superheated steam turbines, 26 135-136 Superheating, in vapor-compression refrigeration systems, 21 543-545 SuperHeavy Elements (SHEs), 1 465, 494-499... 

Superheavy Elements Island of Stability. LBNL Image Library. http //www.imglib.Ibl.gov. ImgLib/COLLECTlONS/ BERKELEY-LAB/SEABORG-ARCHIVE (accessed October 23, 2005). 

GENERALIZED RECP ACCOUNTING FOR BREIT EFFECTS URANIUM, PLUTONIUM AND SUPERHEAVY ELEMENTS 112, 113, 114... 

Investigation of physical and chemical properties of recently synthesized, relatively long-living isotopes of superheavy elements (SHEs) with nuclear charges Z=105 to 116 [1, 2, 3, 4] and their compounds is of fundamental importance. Their measured lifetimes may reach several hours and the nuclei near the top of the island of stability are predicted to exist for many years. The experimental study of the SHE properties is very difficult be-... 

Zgp O.7, Zg 0.4, Zjg 0.3. Thus, Bcc>, Bcv, and B > contributions are negligible for the chemical accuracy of calculation. Therefore, the above made estimates provide us a good background for approximating the Breit interaction by a one-electron GRECP operator that should work well both for actinides and for superheavy elements. The numerical tests of the GRECPs accounting for the Breit effects are discussed in the next section. 

Different nuclear models and contributions of the Breit interaction between valence, inner and outer core shells of uranium, plutonium and superheavy elements El 12, E113, and El 14 are considered in the framework of allelectron four-component and (G)RECP methods. It is concluded on the basis of the performed calculations and theoretical analysis that the Breit contributions with inner core shells must be taken into account in calculations of actinide and SHE compounds with chemical accuracy whereas those between valence and outer core shells can be omitted. 

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