Each element has at least one isotope with unstable nuclei that can undergo radioactive decay.

每个元素至少有一个同位素不稳定原子核可以进行放射性衰变。

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Being a company of utter geeks, Google called this beta test laptop the Cr-48 after the chemical name of an unstable isotope of the chrome element.

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Fission comes from the relatively unstable isotope u-235.

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