| Pa | Protactinium | Atomic number : 91 Relative atomic mass (12C = 12.0000) : 231.03588 |
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| 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. |
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| G E O L O G I C A L D A T A | |
| Abundances 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 : nil |
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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. |