Radon
See also: Radon (homonymy), RN
The radon is a chemical element periodic table of symbol RN and Atomic number 86.
It is a rare gas radioactive, of natural origin, which is formed by the Désintégration Radium. Its most stable Isotope is the 222Rn which has a Demi-vie 3,8 days and is used in Radiothérapie.
Notable characteristics
inert Gas, radon is heaviest of the rare gases, and one of the heaviest gases to room temperature. (The heaviest gas is the Uranium hexafluoride). With Temperature and Pression standard radon is without color, but when the Température is lowered in lower part of its point of Congélation (202 K; -71 °C), it becomes phosphorescent then yellow if the Température still drops and finally orange-red at the temperatures of the liquid air (< -180 °C).
The radon concentration in the terrestrial atmosphere is very weak, for this reason natural water continuously slackens radon, resulting from the rocks. The level is lower in urban area than in zone rurale.
It is particularly present in the granitic, volcanic and uranium-bearing areas. In France, the areas rich in radon are the Brittany, the Massif Central, the the Vosges and the Corsica . The Digs, the Lozere, the Tarn and the Corse-du-Sud has, in the buildings, of the amounts higher than 250 Bq /m ³. The lowest rates are in the Landes (28 Bq/m ³: sedimentary nature of the grounds).
He is regarded as poison for the Santé and would be responsible in Europe for 9% of the deaths by Lung cancer (even level that passive smoking). There is not for the moment of obligation for the habitat
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