| 释义 |
Francium [英] [ˈfrænsɪəm] [美] [ˈfrænsiəm] [名] 钫(元素符号为 Fr) 词频排名 42233/55435 学习人数 86 难度等级 2/10 认知比例 56.25% 例句 Fr for Francium Fr代表钫 助记 其他 "名词 an unstable radioactive element of the alkali-metal group, occurring in minute amounts in uranium ores. Symbol: Fr; atomic no: 87; half-life of most stable isotope, 223Fr: 22 minutes; valency: 1; melting pt: 27°C; boiling pt: 677°C 钫"
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