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Protactinium

Metal radioactivesolid
Symbol: Pa
Atomic number: 91
Atomic mass: 231.03588
Group: Actinide
CAS-number: 7440-13-3

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Physical data
Isotopes
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Physical data

Electronic dataThermal dataSteric data
Shells: 2, 8, 18, 32, 20, 9, 2
Orbitals: [Rn] 5f2 6d1 7s2
Electronegativity: --, 1.1
1. Ionization potential: 5.89 eV
2. Ionization potential: -- eV
3. Ionization potential: -- eV
Oxidation states: 5, 4
Electrical conductivity: 0.0529 10^6
Melting point: 1600 °C
Boiling point: -- °C
Specific heat: 0.12 J/gK
Heat of fusion: 12.30 kJ/mol
Heat of vaporization: -- kJ/mol
Thermal conductivity: 0.47 W/cmK
Atomic radius: -- Å
Ionic radius: -- Å
Covalent radius: -- Å
Atomic volume: 15.0 cm³/mol
Density (293 K): 15.4 g/cm³
Crystal structure: orthorhombic
orthorhombic

Isotopes

NuclideAbundance [%]MassSpinHalflifeDecay modeDecay tree
230Pa 0 230 2 17.4d EC, β-, α View
231Pa 0 231.036 3/2 3.28E04y α View
233Pa 0 233 3/2 27.0d β- View
234Pa 0 234 4 6.69h β- View
234Pam 0 234 0 1.17m β-, IT View

Other info

Name origin:Greek: proto and actinium (parent of actinium); it forms actinium when it radioactively decays.
Description:Very rare, silvery-white, extremely radioactive metal.
Discovered by:Fredrich Soddy, John Cranston, Otto Hahn, Lise Meitner
Year:1917
Place:England/France
Sources:Does not occur in nature. Found among fission products of uranium, thorium, and plutonium.
Use(s):It has no significant commercial applications.