radon(redirected from Element 86)
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n. Symbol Rn
A colorless, radioactive, inert gaseous element that is formed by the radioactive decay of radium and is used to produce neutrons for research. Its most stable isotope is Rn-222 with a half-life of 3.82 days. A natural source of radiation found in most soils and groundwater, radon poses a serious health threat if inhaled. Atomic number 86; melting point -71°C; boiling point -61.7°C; density of gas 9.73 grams per liter; specific gravity (solid) 4. See Periodic Table.
(Elements & Compounds) a colourless radioactive element of the rare gas group, the most stable isotope of which, radon-222, is a decay product of radium. It is used as an alpha particle source in radiotherapy. Symbol: Rn; atomic no: 86; half-life of 222Rn: 3.82 days; valency: 0; density: 9.73 kg/m3; melting pt: –71°C; boiling pt: –61.7°C
[C20: from radium + -on]
a chemically inert, radioactive gaseous element produced by the decay of radium: emissions produced by outgassing of rock, brick, etc., are a health hazard. Symbol: Rn; at. no.: 86; at. wt.: 222.
Symbol Rn A colorless, odorless, radioactive element that is a noble gas. It is produced by the radioactive decay of radium and occurs in minute amounts in soil, rocks, and the air near the ground. Radon is used as a source of radiation for the treatment of cancer and other diseases. Its most stable isotope has a half-life of about four days. Atomic number 86. See Periodic Table.
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|Noun||1.||radon - a radioactive gaseous element formed by the disintegration of radium; the heaviest of the inert gasses; occurs naturally (especially in areas over granite) and is considered a hazard to health|
chemical element, element - any of the more than 100 known substances (of which 92 occur naturally) that cannot be separated into simpler substances and that singly or in combination constitute all matter