34Se78.971

Sélénium

Reactive nonmetalsBlock pPeriod 4Group 16solid at 20 °C
Configuration :[Ar] 3d¹⁰ 4s² 4p⁴
Atomic mass :78.971 u
English :Selenium
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Modèle de Bohr · pédagogique

Electron configuration

Full1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p⁴
Short[Ar] 3d¹⁰ 4s² 4p⁴
Valence electrons6
KLMNOPQ shells
K2
L8
M18
N6

Electronegativity

Pauling2.55
Allen2.424
Mulliken (eV)

Atomic radii

Empirical115 pm
Calculated103 pm
Covalent120 pm
Van der Waals190 pm
Ionic radii (Shannon-Prewitt)
-2198 pm

Successive ionisation energies

I₁941 kJ/mol
I₂2045 kJ/mol
I₃2973.7 kJ/mol
I₄4144 kJ/mol
I₅6590 kJ/mol
Electron affinity195 kJ/mol

Oxidation states

-2-1+1+2+3+4+5+6
Bold states = most common.
Period 4Block pIUPAC Group 16Family Reactive nonmetals
Sources : NIST Atomic Weights & Isotopic Compositions, IUPAC Recommendations, CODATA. Methodology