APP A radioactive element of thealkali-metal group. It is found on Earthonly as a short-lived product of radioac-tive decay,occurring in uranium ores in mi-nute quantities. A large number of radioi-sotopes of francium are known.Symbol:Fr;m. p. 27℃;b. p.677℃;p......（本文共 381 字） [阅读本文] >>
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