actinium

actinium definition - medical

ac·tin·i·um (ăk-tĭnˈē-əm)

noun Symbol Ac
A radioactive element found in uranium ores. Its longest lived isotope is Ac 227 with a half-life of 21.6 years. Atomic number 89.

The American Heritage® Medical Dictionary Copyright © 2009 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

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