Radon

Radon, chemical element, symbol Rn; for physical constants see Periodic Table. Radon was discovered by Friedrich E. Dorn in 1900. Radon is present in the air to the extent of one part in 10²¹ and occurs in some spring waters, such as those at Hot Springs, Ark. Radon is a colorless, odorless, and chemically inert gas. It is a radioactive byproduct of the alpha-decay of radium, thorium, and actinium and is a member of the noble, or inert gases. It is the heaviest known gas. It has been reported that fluorine reacts with radon to form radon fluoride. Radon is a radiation hazard, and remedial action is recommended for homes where the activity is greater than 4 picocuries/liter.