Cobalt
Cobalt is a chemical element with symbol Co and atomic number 27. Like nickel, cobalt in the Earth's crust is found only in chemically combined form, save for small deposits found in alloys of natural meteoric iron. The free element, produced by reductive smelting, is a hard, lustrous, silver-gray metal.
A stylized shell model. Electrons are quantum objects, not particles following these literal paths. Sizes and motion are illustrative.
18 is the [Ar] core total across three shells.
At a glance
- Atomic number
- 27
- Atomic mass
- 58.933194 u
- Phase
- Solid
- Density
- 8.9 g/cm³
- Melting point
- 1,768 K
- Boiling point
- 3,200 K
- First ionization energy
- 760.4 kJ/mol
- Electronegativity
- 1.88
- Electron affinity
- 63.898 kJ/mol
- Molar heat capacity
- 24.81 J/(mol·K)
- Period
- 4
- Appearance
- hard lustrous gray metal
Conditions and isotopes affect measured properties. Some properties of short-lived elements are predicted. Electronegativity uses the Pauling scale.
Keep exploring
Explore the stories, imagery, and reference data in more depth. Properties with no value in the reference are marked unavailable.