from The American Heritage® Dictionary of the English Language, 4th Edition

  • n. A rare, extremely toxic, radioactive element chemically similar to uranium, having 13 known isotopes, the most common of which is protactinium 231 with a half-life of 32,480 years. Atomic number 91; melting point 1,230°C; specific gravity 15.37; valence 4, 5. See Table at element.

from Wiktionary, Creative Commons Attribution/Share-Alike License

  • n. A chemical element (symbol Pa) with atomic number 91.

from the GNU version of the Collaborative International Dictionary of English

  • The radioactive chemical element, of atomic number 91; Atomic symbol Pa; at. wt. of longest-lived isotope, 231 (T1/2 = 32,500 yrs.) Also called brevium, Uranium X2 and UX2.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

  • n. a short-lived radioactive metallic element formed from uranium and disintegrating into actinium and then into lead


from The American Heritage® Dictionary of the English Language, 4th Edition

prot(o)- + actinium (so called because it decays into actinium).

from Wiktionary, Creative Commons Attribution/Share-Alike License

proto- +‎ actinium.


  • An element discovered in 1982 has been named meitnerium to honor Lise Meitner (1878-1968), the Austrian-Swedish physicist and mathematician who discovered the element protactinium and made major contributions to the understanding of nuclear fission.


  • Her expertise was on separating protactinium from carnotite and she had previously worked as a consultant for physicians and hospitals. 141

    Trafficking Materials and Gendered Experimental Practices: Radium Research in Early 20th Century Vienna

  • Kudos to moose drool whose handle happens to rhyme with April Fools, too! for the initial protactinium outline.

    New Levels of LEED

  • LEMON cerium germanium gold hafnium iodine iron lanthanum neodymium phosphorus praseodymium protactinium samarium scandium silver sulphur thorium titanium uranium vanadium yttrium zirconium

    Zolar’s Magick Of Color

  • Professor Meitner in 1918, and discovered protactinium, the long-lived mother substance of the actinium series.

    Otto Hahn - Biography

  • However, as U238 decays into its daughter products thorium and protactinium, both beta and gamma radiation are released, increasing the radiation burden further.


  • And gold and protactinium and indium and gallium, (gasp)

    Qulog 2.0

  • Coalesced work from home online jobs, red kindliness, red granger and mastoidal aldol, but postnatal pylon say protactinium to pelvimetry the satiety are reputably way.



Log in or sign up to get involved in the conversation. It's quick and easy.

  • Pa.

    December 16, 2007