praseodymium

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Symbol:

Pr

Atomic Number:

59

Relative Atomic Mass:

140.90765 g mol^-1

Natural Abundance in Lithosphere, hydrosphere and atmosphere:

5 x 10^-4% (mass fraction)

Electron Configuration:

[Xe]4f³6s²

Oxidation States:

IV, III

Atomic Radius:

182pm

Covalent Radius:

165pm

Ionic Radius:

85pm (for +4 oxidation state)

99pm (for +3 oxidation state)

Melting Point:

931°C

Density:

6.48 g cm^-3 (at 20°C)

First Ionisation Energy:

5.42 eV

Reduction Potential:

-2.35V

for Pr³⁺ + 3e^- a Pr_(s)

Electronegativity (Allred and Rochow):

1.1

Number of Natural Isotopes:

1

Mass Number of the Most Abundant Isotopes:

141 g mol^-1 a 100% abundance