- a radioactive element of the lanthanide series artificially produced by the fission of uranium. Symbol: Pm; atomic no: 61; half-life of most stable isotope, 145Pm: 17.7 years; valency: 3; melting pt: 1042°C; boiling pt: 2460°C (approx.)
| 单词 | promethium |
| 释义 | WordReference Random House Unabridged Dictionary of American English © 2024 pro•me•thi•um (prə mē′thē əm),USA pronunciation n. [Chem.]
Collins Concise English Dictionary © HarperCollins Publishers:: promethium /prəˈmiːθɪəm/ n
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