Cobalt
Transition Metal
Cobalt (Co) is a chemical element with atomic number 27, classified as a transition metal. At room temperature it is a solid. It was discovered in 1735 by Georg Brandt.
Properties
- Atomic number
- 27
- Atomic mass
- 58.933 u
- Category
- Transition Metal
- Group
- 9
- Period
- 4
- Block
- d-block
- Electron configuration
- [Ar] 3d⁷ 4s²
- Phase at STP
- Solid
- Density
- 8.86 g/cm³
- Melting point
- 1768 K (1494.8 °C)
- Boiling point
- 3200 K (2926.8 °C)
- Electronegativity
- 1.88
- Atomic radius
- 152 pm
- Ionization energy
- 7.881 eV
- Discovery
- 1735 · Georg Brandt
Common uses
Batteries, magnets, blue pigments, medical implants
Did you know?
Critical for lithium-ion batteries and creates brilliant blue glass.
Experiment with the elements
Cobalt doesn't form any compounds in our lab yet, but the periodic table sandbox lets you combine dozens of other real elements into real compounds — water, table salt, ammonia and many more — with their true chemical formulas.