Radon properties

The following properties of the Radon transform can be readily verified... 

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. 

Radon is the heaviest of the hehum-group elements and the heaviest of the normal gaseous elements. It is strongly radioactive. The most common isotope, Rn, has a half-life of 3.825 days (49). Radon s scarcity and radioactivity have severely limited the examination of its physical properties, and the values given ki Table 3 are much more uncertain than are the values Hsted for the other elements. 

The isolation and identification of 4 radioactive elements in minute amounts took place at the turn of the century, and in each case the insight provided by the periodic classification into the predicted chemical properties of these elements proved invaluable. Marie Curie identified polonium in 1898 and, later in the same year working with Pierre Curie, isolated radium. Actinium followed in 1899 (A. Debierne) and the heaviest noble gas, radon, in 1900 (F. E. Dorn). Details will be found in later chapters which also recount the discoveries made in the present century of protactinium (O. Hahn and Lise Meitner, 1917), hafnium (D. Coster and G. von Hevesey, 1923), rhenium (W. Noddack, Ida Tacke and O. Berg, 1925), technetium (C. Perrier and E. Segre, 1937), francium (Marguerite Percy, 1939) and promethium (J. A. Marinsky, L. E. Glendenin and C. D. Coryell, 1945). 

Radon is a noble gas and is therefore not readily ionized or chemically reactive. Its properties in terrestrial material will be controlled by its solubility in melt and fluid as well as its diffusion coefficients. Compared with the lighter noble gases, Rn diffuses more slowly and has a lower solubility in water. It will also more readily adsorb onto surface that the lighter rare gases. It can, however be lost by degassing in magmatic systems (Condomines et al. 2003). More information about the behavior of Rn can be found in Ivanovich and Harmon (1992). 

James A. 1987. A reconsideration of cells at risk and other key factors in radon daughter dosimetry. In Hopke P, ed. Radon and its decay products Occurrence, properties and health effects. ACS Symposium Series 331. Washington, DC American Chemical Society, 400-418. 

Radon and its decay products were a major focus of meetings held in Capri, Italy, in 1983 and in Maastricht, the Netherlands, in 1985. These meetings reported on ongoing national surveys in European countries, on laboratory and field studies on the properties of radon decay products, and on the models for relating the airborne radioactivity concentrations to the human lung. 

In order to focus on more of the basic research problems related to radon, a symposium was organized in conjunction with the 191th National Meeting of the American Chemical Society. This volume presents most of the reports given at that symposium. There are five major groups of reports occurrence, measurement methods, physical and chemical properties of radon and its decay products, health effects, and mitigation of radon levels. 

The physico-chemical properties of radon and its decay products are presented in a series of reports primarily focusing on the decay products. However, Stein (1987) presents a review of his pioneering studies of radon chemistry and the reactions of radon with strong oxidizing agents. Although radon is not chemically active in indoor air, it is interesting to note that radon is not an "inert gas. 

Jonassen, N., Electrial Properties of Radon Daughters, presented to the International Conference on Occupational Radiation Safety and Mining, Toronto, Canada (1984). 

Stein, L., Chemical Properties of Radon, this volume (1987). 

Since the discovery of the first noble gas compound, Xe PtF (Bartlett, 1962), a number of compounds of krypton, xenon, and radon have been prepared. Xenon has been shown to have a very rich chemistry, encompassing simple fluorides, XeF2> XeF, and XeF oxides, XeO and XeO oxyf luorides, XeOF2> XeOF, and Xe02 2 perxenates perchlorates fluorosulfates and many adducts with Lewis acids and bases (Bartlett and Sladky, 1973). Krypton compounds are less stable than xenon compounds, hence only about a dozen have been prepared KrF and derivatives of KrF2> such as KrF+SbF, KrF+VF, and KrF+Ta2F11. The chemistry of radon has been studied by radioactive tracer methods, since there are no stable isotopes of this element, and it has been deduced that radon also forms a difluoride and several complex salts. In this paper, some of the methods of preparation and properties of radon compounds are described. For further information concerning the chemistry, the reader is referred to a recent review (Stein, 1983). 

Effect of Radon on Some Electrical Properties of Indoor Air... 

Wilkening, M.H., M. Kawano, and C. Lane, Radon Daughter Ions and Their Relation to Some Electrical Properties of the Atmosphere, Tellus 18 679-684 (1966). 

It should be stressed that the field-ions related measurements are still of a very preliminary nature. Work is in progress both on determining the fundamental electrical properties of the radon progeny and based on this on the influence on progeny removal of electrode configuration etc. 

Jonassen, N., Electrical Properties of Radon Daughters in Proc. Int. Conf. Occupational Radiation Safety in Mining,... 

II and III). This result was expected because of the well known adsorptive properties of carbon for radon and thoron. However, the activated carbon data on Tables II and III is in sharp disagreement with previous, and numerous, data obtained in the large RTTF (see Table I). This topic is under investigation. It should be noted that there are substantial quantitative differences between the behaviour of the radon and thoron progeny relative to activated carbon. 

It has been found that the "unattached" fraction is an ultrafine particle aerosol with a size range of 0.5 to 3 nm. In order to initiate studies on the formation mechanism for these ultrafine particles, a series of experiments were made in the U.S. Bureau of Mines radon chamber. By introducing SO into the chamber, particles were produced with an ultrafine size distribution. It has been found that the particle formation mechanism is supressed by the presence of radical scavengers. These experiments suggest that radiolysis following the decay of Rn-222 gives rise to the observed aerosol and the properties of the resulting aerosol are dependent on the nature and the amount of reactive gas present. 

Martell, E. A., and K. S. Sweder, Properties of radon progeny in mainstream cigarette smoke and the alpha dose at segmental bifurcations of smoke, in Current Topics in Lung Dosimetry, (D. R. Fisher, ed.) pp. 144-151, CONF-820492, NTIS, U. S. Department of Commerce, Springfield, Virginia (1983). 

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