Atomic Number: 86
Atomic Symbol: Rn
Atomic Weight: 222
Melting Point: -95 F (-71 C)
Boiling Point: -79 F (-61.7 C)
Word origin: The word radon is derived from radium, of which radon is a gas. Early in its discovery it was also called radium emanation and niton, which comes from the Latin nitens, meaning shining. Since 1923, however, it has been called radon.
Discovery: German physicist Friedrich Ernst Dorn discovered radon in 1900. He called it radium emanation. Eight years later, William Ramsay and Robert Whytlaw Gray isolated radon, determined its density, and named it niton.
Properties of radon
Radon holds the last place in the group of noble gases in the Periodic Table. It is the heaviest known gas, is radioactive, and is essentially inert. At ordinary temperatures, radon is a colorless gas, but when it is cooled below its freezing point it gains a stunning phosphorescence. The glow becomes yellow as the temperature is lowered and orange-red at the temperature of liquid air.
Fluorine is reported to react with radon, forming a fluoride. Additionally, radon clathrates have been reported.
Radon should be handled with care, as its inhalation can cause health problems. The Environmental Protection Agency estimates that it is responsible for an estimated 20,000 lung cancer deaths each year. It can collect in uranium mines and buildings. In the United States, it is recommended that action be taken if the air in homes has more than 4 pCi/l of radon.
Radon has 20 known isotopes, of which R-226 is the most common. It is an alpha-emitter with 1601 years of half-life.
Sources of radon
Radon is a gas produced by the decay of radium. An estimated 1 gram of radium is present in every square mile of soil to a depth of 6 inches. This radium emits tiny amounts of radon into the atmosphere. On average, one part of radon is present in 1 x 1021 part of air.Radon is also present in some spring waters, including Hot Springs, Ark.
Uses of radon
Radon is sometimes used by hospitals to treat cancer and other diseases. Hospitals used to produce it themselves by pumping radon from a radium source and sealing it in small tubes called seeds or needles. This is no longer a widespread practice because hospitals can get the seeds directly from suppliers, who can customize the seeds for the desired use.
(Source: Los Alamos National Laboratory)