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91Pa231.035
Protactinium
ActinidesBlock fPeriod 7solid at 20 °C
Configuration :[Rn] 5f² 6d¹ 7s²
Atomic mass :231.03588 u
3D Bohr-model representation of the Protactinium atom (symbol Pa, atomic number Z=91). Electron shell configuration: 2, 8, 18, 32, 20, 9, 2 electrons.
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Bohr model · educational
Electron configuration
Full[Rn] 5f² 6d¹ 7s²
Short[Rn] 5f² 6d¹ 7s²
Valence electrons5
KLMNOPQ shells
K2
L8
M18
N32
O20
P9
Q2
Electronegativity
Pauling1.5
Allen—
Mulliken (eV)—
Atomic radii
Empirical180 pm
Calculated—
Covalent200 pm
Van der Waals—
Ionic radii (Shannon-Prewitt)
+578 pm
Successive ionisation energies
I₁568 kJ/mol
Electron affinity—
Oxidation states
+2+3+4+5
Bold states = most common.