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|Atomic Number:||86||Atomic Symbol:||Rn|
|Atomic Weight:||222||Electron Configuration:||2-8-18-32-18-8|
|Melting Point:||-71oC||Boiling Point:||-61.8oC|
|Description:||Colorless,odorless,tasteless radioactive noble gas.|
|Uses:||Used to treat some forms of cancer|
History(From radium; called niton at first, L. nitens, shining) The
element was discovered in 1900 by Dorn, who called it radium emanation. In 1908
Ramsay and Gray, who named it niton, isolated the element and determined its
density, finding it to be the heaviest known gas. It is essentially inert and
occpies the last place in the zero group of gases in the Periodic Table. Since
1923, it has been called radon.
IsotopesTwenty isotopes are known. Radon-22, from radium, has a
half-life of 3.823 days and is an alpha emitter; Radon-220, emanating naturally
from thorium and called thoron, has a half-life of 55.6 s and is also an alpha
emitter. Radon-219 emanates from actinium and is called actinon. It has a
half-life of 3.96 s and is also an alpha emitter.
- It is estimated that every square mile of soil to a depth of 6 inches
contains about 1 g of radium, which releases radon in tiny amounts into the
- Radon is present in some spring waters, such as those at Hot Springs,
- On the average, one part of radon is present ot 1 x 10^21 part of air.
- At ordinary temperatures radon is a colorless gas; when cooled below the
freezing point, radon exhibits a brilliant phosphorescence which becomes yellow
as the temperature is lowered and orange-red at the temperature of liquid air.
- It has been reported that fluorine reacts with radon, forming a fluoride.
- Radon clathrates have also been reported.
UsesRadon is still produced for therapeutic use by a few hospitals by
pumping it from a radium source and sealing it in minute tubes, called seeds or
needles, for application to patient. This practice has been largely discontinued
as hosptials can get the seeds directly from suppliers, who make up the seeds
with the desired activity for the day of use.
- Care must be taken in handling radon, as with other radioactive materials.
- The main hazard is from inhalation of the element and its solid daughters
which are collected on dust in the air.
- Good ventilation should be provided where radium, thorium, or actinium is
stored to prevent build-up of the element.
- Radon build-up is a health consideration in uranium mines.
- Recently radon build-up in homes has been a concern.
- Many deaths from lung cancer are caused by radon exposure.
- In the U.S. it is recommended that remedial action be taken if the air in
homes exceeds 4 pCi/l.
CostsRadon is available at a cost of about $4/m.