| 单词 | promethium |
| 释义 | Word Frequency promethium or prometheum (prəˈmiːθɪəm) noun 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.) Word origin C20: New Latin from Prometheus |
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