单词 | radon |
释义 | ra·don ![]() 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. [RAD(IUM) + –ON2.] |
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