radioactive series

noun

: a series of elements that are formed by disintegration of a long-lived parent (as actinium, thorium, or uranium) through the successive loss of alpha or beta particles sometimes by alternative routes and that are all radioactive except the end products which are stable isotopes of lead or bismuth — compare neptunium series

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Physics, Chem.

a succession of elements initiated in the radioactive decay of a parent, as thorium or uranium, each of which decays into the next until a stable element, usually lead, is produced. Also called decay series.

[1920-25]

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radioactive series,

one of several series of isotopes of certain elements representing various stages of disintegration of a radioactive substance. Three of these series occur naturally (the actinium, thorium, and uranium series) and others, such as the neptunium series, are artificially produced.