Radon difluoride 's a compound of radon, a noble gas. Radon reacts readily with fluorine to form a solid compound, but this decomposes on attempted vaporization and its exact composition's uncertain. Calculations suggest that it may be ionic. The usefulness of radon compounds's limited because of the radioactivity of radon: the longest-lived isotope has a half-life of only 3.82 days.… (More on Rnf)