| 单词 | actinium |
| 释义 | Word Frequency actinium(ækˈtɪnɪəm) noun a radioactive element of the actinide series, occurring as a decay product of uranium. It is used as an alpha-particle source and in neutron production. Symbol: Ac; atomic no: 89; half-life of most stable isotope,227Ac: 21.6 years; relative density: 10.07; melting pt: 1051°C; boiling pt: 3200 ± 300°C Word origin C19: New Latin, from actino- + -ium |
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