Radon atomic properties

The relativistic coupled cluster method starts from the four-component solutions of the Drrac-Fock or Dirac-Fock-Breit equations, and correlates them by the coupled-cluster approach. The Fock-space coupled-cluster method yields atomic transition energies in good agreement (usually better than 0.1 eV) with known experimental values. This is demonstrated here by the electron affinities of group-13 atoms. Properties of superheavy atoms which are not known experimentally can be predicted. Here we show that the rare gas eka-radon (element 118) will have a positive electron affinity. One-, two-, and four-components methods are described and applied to several states of CdH and its ions. Methods for calculating properties other than energy are discussed, and the electric field gradients of Cl, Br, and I, required to extract nuclear quadrupoles from experimental data, are calculated. 

We call a Radon partition A, B minimal if and only if it is not possible to remove an atom from either set A or B without destroying the Radon partition property. In other words, the Radon partition A, B is minimal if and only if there is no Radon partition A, B A, B with A c A and B c b. 

Pure Elements. AH of the hehum-group elements are colorless, odorless, and tasteless gases at ambient temperature and atmospheric pressure. Chemically, they are nearly inert. A few stable chemical compounds are formed by radon, xenon, and krypton, but none has been reported for neon and belium (see Helium GROUP, compounds). The hehum-group elements are monoatomic and are considered to have perfect spherical symmetry. Because of the theoretical interest generated by this atomic simplicity, the physical properties of ah. the hehum-group elements except radon have been weU studied. 

Uranium-238 emits an alpha particle to become an isotope of thorium. This unstable element emits a beta particle to become the element now known as Protactinium (Pa), which then emits another beta particle to become an isotope of uranium. This chain proceeds through another isotope of thorium, through radium, radon, polonium, bismuth, thallium and lead. The final product is lead-206. The series that starts with thorium-232 ends with lead-208. Soddy was able to isolate the different lead isotopes in high enough purity to demonstrate using chemical techniques that the atomic weights of two samples of lead with identical chemical and spectroscopic properties had different atomic weights. The final picture of these elements reveals that there are several isotopes for each of them. 

The chemical and electrochemical characteristic properties of elements are determined by the electrons in the last outer shell. Elements with outer levels filled to completion, i. e. the rare gases (helium, neon, argon, crypton, xenon and radon), are noted for the great stability of their electronic structures atoms of such elements, known for their chemical inactivity, do not show any tendency to form molecules, neither in mutual bonds nor in bonds with other atoms. 

After helium and argon had been discovered the existence of neon, krypton, xenon, and radon was clearly indicated by the periodic law, and the search for these elements in air led to the discovery of the first three of them radon was then discovered during the investigation of the properties of radium and other radioactive substances. While studying the relation between atomic structure and the periodic law Niels Bohr pointed out that element 72 would be expected to be similar in its properties to zirconium. G. von Hevesy and D. Coster were led by this observation to examine ores of zirconium and to discover the missing element which they named hafnium. 

The group 8A elements, known as the noble gases, are all nonmetals that are gases at room temperature. They are all monatomic (that is, they consist of single atoms rather than molecules). Some physical properties of the noble-gas elements are listed in V TABLE 7.8. The high radioactivity of radon (Rn, atomic number 86) has limited the study of its reaction chemistry and some of its properties. 

Smirnov BM (1993) Mechanisms of melting of rare gas solids. Physica Scripta 48 483-486 Runeberg N, Pyykko P (1998) Relativistic pseudopotential calculations on Xe2, RnXe, and Ru2 the van der Waals properties of radon. Int J Quantum Chem 66 131-140 Batsanov SS (1998) Some characteristics of van der Waals interaction of atoms. Russ J Phys Chem 72 894-897... 

Suppose that scientists were to discover a new element, one that has the chemical properties of the noble gases, and positioned directly below radon on the periodic table. Assuming that the g orbitals of the elements preceding it in the period had not yet begun to fill, what would be the atomic number and ground state electron configuration of this new element ... 

Figure 19.2 shows the noble gases superimposed on the network of interconnected ideas. Table 19.1 is a slightly amended version of the usual table of periodic properties. Note that these properties are exactly as expected on the basis of effective nuclear charge and the distance of the valence electrons from that charge. Consistent with the noble nature of these elements, the usual entries for atomic and ionic radii have been replaced by van der Waals radii. Only two entries, for xenon and krypton, have been made in the table under covalent radii. (Several radon compounds are known, but the covalent radius has not been well-established.) As expected, these radii increase regularly down the group. 

Due to the expected high volatility of elements with atomic numbers 112 to 118 in their elemental state [125] (see also Theoretical Chemistry of the Heaviest Elements and Thermochemical Data from Gas-Phase Adsorption and Methods of Their Estimation ), gas-phase chemical studies play an important role in investigating their chemical properties. Very early on, it was speculated that, because of relativistic effects and due to their closed 7s 6d and 7s 6d 7py, (sub)shells, Cn and H (FI, Z = 114), respectively, might be very volatile possibly even as volatile as radon [126]. More recent predictions claim that both elements should still retain some metallic character, and thus adsorb quite well on certain metal surfaces [127]. Semiempirical extrapolations [128] point to Pd, Cu, and Au as ideal surfaces for the adsorption of superheavy elements. 

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