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Definition: radon from Philip's Encyclopedia

(symbol Rn) Radioactive gaseous element, a noble gas which is the densest gas known. It was first discovered (1899) by New Zealand-born British physicist Ernest Rutherford. The 20 known isotopes, which are alpha particle emitters, are present in the Earth's atmosphere in trace amounts. Radon is mainly used in medical radiotherapy. Chemically, it is mostly inert but does form fluoride compounds. Properties: 86; r.d. 9.73; m.p. -71°C (-95.8°F); b.p. -61.8°C (-79.24 °F); most stable isotope Rn222 (half-life 3.8 days).

Summary Article: radon
From The Columbia Encyclopedia

(rā'dŏn), gaseous radioactive chemical element; symbol Rn; at. no. 86; mass no. of most stable isotope 222; m.p. about −71 degrees Celsius; b.p. −61.8 degrees Celsius; density 9.73 grams per liter at STP; valence usually 0. Radon is colorless and the most dense gas known. Chemically unreactive, it is classed as an inert gas in Group 18 of the periodic table. Synthesis of radon fluoride has been reported.



The Columbia Encyclopedia, © Columbia University Press 2018

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