Pa Protactinium     Atomic number : 91 
    Relative atomic mass (12C = 12.0000) :  231.03588 
    P H Y S I C A L     D A T A
Group 3 actinide
Density / kg m-3 :  15 370 (est.)
Melting point / K :  2113 
Boiling point / K :  c. 4300
    D I S C O V E R Y
Protactinium was discovered in 1913 by Kasimir Fajans and O.H. Göhring as the short lived isotope 234Pa. Isotope 231Pa was discovered in 1917 by Lise Meitner and Otto Hahn at Berlin (Germany), K. Fajans at Karlsruhe (Germany) and by F. Soddy, J.A. Cranston and A. Fleck at Glasgow, Scotland.
    G E O L O G I C A L     D A T A
Sun (relative to H = 1 × 1012) : n.a.
Earth's crust / p.p.m. : traces
Oxidation state : V
Seawater / p.p.m. : 2 × 10-11
    B I O L O G I C A L     D A T A
Level in humans
Organs: nil
Daily dietary intake : nil
Total mass of element
in average (70 kg) person :


NetElements II  

A portrait of protactinium is available on the Visual Elements site. Up to 200 individual items of information on this element are available in The Elements.

Text copyright John Emsley 1999.   HTML and page layout copyright Simon Hall 1999.
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NetElements II last modified October 27th, 1999