How does the half life of a nuclide relate to the stability of the nuclide?

A long half-life indicates higher stability and vice versa.

Half-life is a measure of how long it takes for one half of the atoms of a nuclide to undergo radioactive decay. A short half-life indicates that the nuclides decay quickly, while a long one indicates they decay more slowly.

With this in mind, an atom won't decay until it's so unstable that it can't avoid undergoing decay. As a result, a long half-life indicates higher stability than short half-life.

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