这些元素都有放射性，而且性质与锕相似。
All are radioactive and have similar properties to actinium.
锕射气氡的一种放射性的，惰性的和气态的同位素，其半衰期为3。92秒。
A radioactive, inert, gaseous isotope of radon, with a half - life of3.92seconds.
锘在锕类元素中的一种放射性超铀元素，人工微量制造，其最长寿命的同位素是锘255，其。
A radioactive transuranic element in the actinide series, artificially produced in trace amounts. Its longest-lived isotope is No255 with a half-life of3 minutes. Atomic number102.
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