radon(redirected from 222Rn)
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a chemical element, atomic number 86, atomic weight 222, symbol Rn. (See Appendix 6.) Radon is a colorless, gaseous, radioactive element produced by the disintegration of radium.
A gaseous radioactive element, atomic no. 86, resulting from the breakdown of radium; of the isotopes with mass numbers between 198 and 228, only 222Rn is medically significant as an α-emitter, with a half-life of 3.8235 days; it is used in the treatment of certain malignancies. Poorly ventilated homes in some parts of the country have accumulated a dangerous amount of naturally occurring radon gas.
radon/ra·don/ (ra´don) a gaseous radioactive element, at. no. 86, symbol Rn, resulting from decay of radium.
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.
Etymology: L, radiare, to emit rays
a radioactive, chemically inert, gaseous element. Its atomic number is 86, and its atomic mass is 222. A decay product of radium, radon is used in radiation cancer therapy. Radon is also released by rocks, soil, and groundwater and is a common source of background radiation, with an intensity that varies in different geographic areas.
radonA naturally occurring radioactive gas in the decay chain of uranium-238 to lead-206, which has a half-life of 3.8 days; it decays into two solid, alpha-particle-emitting daughters. Radon exposure is associated with 13-fold increased risk of lung cancer in non-smoking uranium miners; it also increases the risk of childhood cancer, myeloid leukaemia, renal cell carcinoma, melanoma and prostate cancer.
13,000 annual excess cases of lung cancer in the US are attributed to radon gas. Long-term exposure to 150 Bq/m3 is equivalent to smoking half a pack of cigarettes a day; at ≥ 10.8 pCi/L (400 Bq/m3), the relative risk is 1.8; combined radon exposure and smoking exceed an additive and approach a multiplicative effect.
radon222Ra Public health A natural radioactive gaseous element, atomic number 86; atomic weight, 211.4 in the 238U → 206Pb decay chain; radon has a T1⁄2 of 3.8 days, decays into 2 solid α particle-emitting daughters; radon exposure carries a relative risk of 12.7 for lung CA in non-smoking uranium miners and an ↑ risk of childhood CA, myelogenous leukemia, renal cell carcinoma, melanoma, prostate CA. See Radionics, Radium Dial Company.
A gaseous radioactive element, atomic no. 86, resulting from the breakdown of radium; 222Rn is medically significant as an alpha-emitter with a half-life of 3.8235 days; it is used in the treatment of some malignancies. Poorly ventilated homes in some parts of the United States accumulate a dangerous amount of naturally occurring radon gas.
A gaseous radioactive element, resulting from breakdown of radium; some isotopes used to treat malignancies. Poorly ventilated homes in some parts of the U.S. have accumulated a dangerous amount of naturally occurring radon gas.
n A byproduct of radium decomposition used in radiotherapy.
a chemical element, atomic number 86, atomic weight 222, symbol Rn. See Table 6. Radon is a colorless, gaseous, radioactive element produced by the disintegration of radium.