单词 | uranium |
释义 | Word Frequency uranium(jʊˈreɪnɪəm) noun a radioactive silvery-white metallic element of the actinide series. It occurs in several minerals including pitchblende, carnotite, and autunite and is used chiefly as a source of nuclear energy by fission of the radioisotope uranium-235. Symbol: U; atomic no: 92; atomic wt: 238.0289; half-life of most stable isotope,238U: 451 × 109 years; valency: 2-6; relative density: 18.95 (approx.); melting pt: 1135°C; boiling pt: 4134°C Word origin C18: from New Latin, from Uranus2; from the fact that the element was discovered soon after the planet |
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