The Columbia Encyclopedia, Sixth Edition. Columbia Encyclopedia World Factbook American Heritage Coll.
Radon is colorless and the most dense gas known.
Chemically unreactive, it is classed as an inert gas in group 0 of the periodic table . Synthesis of radon fluoride has been reported. Radon is highly radioactive and has a short half-life. The chief use of radon is in the treatment of cancer by radiotherapy. All naturally occurring radon decays by the emission of alpha particles.