protactinium

protactinium definition - medical

pro·tac·tin·i·um (prōˌtăk-tĭnˈē-əm)

noun Symbol Pa1
A rare, extremely toxic radioactive element having 13 known isotopes, the most stable of which is Pa 231 with a half-life of 32,700 years. Atomic number 91.

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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