Home 91 Pa Protactinium back to the periodic table

Atomic number   91
Symbol   Pa
Atomic weight   231.0359
Density [g/cm3]   15.37
Melting point [°C]   1554
Boiling point [°C]   4030
1st Ionization energy [eV]   ---
Electronic configuration   [Rn] 5f2 6d 7s2
Oxidation number (most stable)   5, 4
Atomic radius [pm]   160.6
Ionic radius [pm]   113 (3+)
Abundance in crustal rocks [ppm]   12
Origin of the name   originally Protoactinium, because it is before actinium in the decay chain
Discovery   1913 independently by Fajans, Russell and Soddy
Uses   no technical significance.

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© 2004 Büro für angewandte Mineralogie · Dr. Stephan Rudolph · D-47918 Tönisvorst
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