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90Th232.037

Thorium

ActinidesBlock fPeriod 7solid at 20 °C
Configuration :[Rn] 6d² 7s²
Atomic mass :232.0377 u
3D Bohr-model representation of the Thorium atom (symbol Th, atomic number Z=90). Electron shell configuration: 2, 8, 18, 32, 18, 10, 2 electrons.
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Bohr model · educational

Electron configuration

Full[Rn] 6d² 7s²
Short[Rn] 6d² 7s²
Valence electrons4
KLMNOPQ shells
K2
L8
M18
N32
O18
P10
Q2

Electronegativity

Pauling1.3
Allen
Mulliken (eV)

Atomic radii

Empirical180 pm
Calculated237 pm
Covalent206 pm
Van der Waals
Ionic radii (Shannon-Prewitt)
+494 pm

Successive ionisation energies

I₁587 kJ/mol
I₂1110 kJ/mol
I₃1930 kJ/mol
I₄2780 kJ/mol
Electron affinity

Oxidation states

+1+2+3+4
Bold states = most common.
Period 7Block fFamily Actinides
Sources : NIST Atomic Weights & Isotopic Compositions, IUPAC Recommendations, CODATA. Methodology