actinium: Meaning and Definition of


Pronunciation: (ak-tin'ē-um), [key]
— n. Chem.
  1. a radioactive silver-white metallic element that glows blue in the dark, resembling the rare earths in chemical behavior and valence. Symbol: Ac; at. no.: 89; at. wt.: 227.
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.
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