Radon compounds

Because radon is a gas under normal circumstances, and its decay-chain parents are not, it can readily be extracted from them for research.

[1] It is inert to most common chemical reactions, such as combustion, because its outer valence shell contains eight electrons.

This produces a stable, minimum energy configuration in which the outer electrons are tightly bound.

Theoretical studies on this molecule predict that it should have a Rn–F bond distance of 2.08 ångström (Å), and that the compound is thermodynamically more stable and less volatile than its lighter counterpart xenon difluoride (XeF2).

[9] The [RnF]+ ion is believed to form by the following reaction:[10] For this reason, antimony pentafluoride together with chlorine trifluoride and N2F2Sb2F11 have been considered for radon gas removal in uranium mines due to the formation of radon–fluorine compounds.

Electromigration studies also suggest the presence of cationic [HRnO3]+ and anionic [HRnO4]− forms of radon in weakly acidic aqueous solution (pH > 5), the procedure having previously been validated by examination of the homologous xenon trioxide.

Avrorin et al. reported in 1982 that 212Fr compounds cocrystallised with their caesium analogues appeared to retain chemically bound radon after electron capture; analogies with xenon suggested the formation of RnO3, but this could not be confirmed.

[7] The standard electrode potential of the Rn2+/Rn couple has been estimated as +2.0 V,[21] although there is no evidence for the formation of stable radon ions or compounds in aqueous solution.