Protactinium (Pa): Atomic number: 91, Atomic mass: 231.0359 g.mol -1, Electronegativity: 1.5, Density: 15.37 g.cm-3 at 20°C, Melting point: 1600 °C, Boiling point: unknown, Vanderwaals radius: unknown, Ionic radius: unknown, Isotopes: 5, Electronic shell: [ Rn ] 5f2 6d1 7s2, Discovered by: K. Kajans and O.H. Gohring in 1913. Protactinium is a silver metallic element that belongs to the actinide group. It is malleable, shiny, silver-gray, radioactive. It does not tarnish rapidly in air, it is attacked by oxygen, steam and acids, but not by alkalis. It is superconductive at temperatures below 1.4 K. Applications: Due to its scarcity, high radioactivity and toxicity, there are currently no uses for protactinium outside of basic scientific research. Protactimium in the environment: Protactimium-231 occurs naturally in uranium ores such as pitchblende, to the extent of 3 ppm in some ores in Zaire. Protactinium is naturally present in soil, rock, surface water, groundwater, plants and animals in very low concentrations (on the order of 1 ppt or 0.1 picocouries (pCi)/g). Read more: http://www.lenntech.com/periodic/elements/pa.htm#ixzz0eb4yvzyo

 

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Protactinium (Pa): Atomic number: 91, Atomic mass: 231.0359 g.mol -1, Electronegativity: 1.5, Density: 15.37 g.cm-3 at 20°C, Melting point: 1600 °C, Boiling point: unknown, Vanderwaals radius: unknown, Ionic r . . . View Full Definition