radioactinium / ˌreɪ di oʊ ækˈtɪn i əm /

📖毕业后词汇放射性内含物放射性内脏放射性内酯放射性内裤

radioactinium 的定义

n. 名词 noun

Chemistry.

  1. the radioactive isotope of thorium having a mass number 227 and a half-life of 18.8 days. Symbol: RdAc, Th 227