Actinium

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Symbol:

Ac

Atomic Number:

89

Relative Atomic Mass:

227.0278 g mol^-1

Natural Abundance in Lithosphere, hydrosphere and atmosphere:

6 x 10^-14% (mass fraction)

Electron Configuration:

[Rn]6d7s²

Oxidation States:

+III

Atomic Radius:

187.8pm

Ionic Radius:

112pm (for +3 oxidation state)

Melting Point:

1050°C

Density:

10.07 g L^-1 (at 1013mbar)

First Ionisation Energy:

6.9 eV

Reduction Potential:

-2.13V

for Ac³⁺ + 3e^- a Ac_(s)

Electronegativity (Allred and Rochow):

1.0

Number of Natural Isotopes:

2