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95Am243

Americium

ActinidesBlock fPeriod 7solid at 20 °C
Configuration :[Rn] 5f⁷ 7s²
Atomic mass :243 u
French :Américium
3D Bohr-model representation of the Americium atom (symbol Am, atomic number Z=95). Electron shell configuration: 2, 8, 18, 32, 25, 8, 2 electrons.
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Electron configuration

Full[Rn] 5f⁷ 7s²
Short[Rn] 5f⁷ 7s²
Valence electrons9
KLMNOPQ shells
K2
L8
M18
N32
O25
P8
Q2

Electronegativity

Pauling1.13
Allen
Mulliken (eV)

Atomic radii

Empirical175 pm
Calculated
Covalent180 pm
Van der Waals
Ionic radii (Shannon-Prewitt)
+397.5 pm

Successive ionisation energies

I₁578 kJ/mol
Electron affinity

Oxidation states

+2+3+4+5+6+7+8
Bold states = most common.
Period 7Block fFamily Actinides
Sources : NIST Atomic Weights & Isotopic Compositions, IUPAC Recommendations, CODATA. Methodology