Cobalt

Document v1 · published by Koskamo · updated 2026-10-04

Cobalt (Co) is chemical element 27, a transition metal in group 9, period 4 (PubChem).

Atomic number: 27
Symbol: Co
Group: 9
Period: 4
Atomic mass: 58.93319 u
Electron configuration: [Ar]4s2 3d7
Electronegativity (Pauling scale): 1.88
Atomic radius (van der Waals): 192 pm
Ionization energy: 7.881 eV
Electron affinity: 0.661 eV
Oxidation states: +3, +2
Standard state: Solid
Melting point: 1768 K
Boiling point: 3200 K
Density: 8.86 g/cm³
Chemical group: Transition metal
Year discovered: 1735

Source and provenance

Original source: pubchem.ncbi.nlm.nih.gov
Published on Koskamo by: Koskamo
Citation version: Document v1
Reuse: PubChem periodic table data (NIH/NLM, pubchem.ncbi.nlm.nih.gov/ptable); group and period from Jefferson Lab via PubChem

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Version history

Published by Koskamo2026-10-04
Version 1