Cobalt (Co)
Cobalt (Co) is element 27, a transition metal. Atomic mass 58.933194, configuration [Ar] 3d⁷ 4s². Properties, isotopes, oxidation states, uses and history, with an interactive 3D atom model.
Key facts
| Atomic number | 27 |
|---|---|
| Symbol | Co |
| Standard atomic weight | 58.933194(3) |
| Category | Transition Metal |
| Group | 9 |
| Period | 4 |
| State at room temperature | Solid |
| Electron configuration | [Ar] 3d⁷ 4s² |
| Valence electrons | 2 (Variable) |
| Common oxidation states | +2, +3 |
| Common ions | No common ions |
| Electronegativity (Pauling) | 1.88 |
| First ionization energy | 760 kJ/mol |
| Electron affinity | 63.87 kJ/mol |
| Atomic radius | 152 pm |
| Density | 8.86 g/cm³ |
| Melting point | 1495°C |
| Boiling point | 2927°C |
| Specific heat | 0.421 J/(g·°C) |
Natural isotopes
- Co-59: Stable
Common uses
- Lithium-ion battery cathodes
- Superalloys (Turbines)
- Blue pigments
Where it matters
- Renewable Energy (EV Batteries)
- Medical (Radiation therapy Co-60)
- Biology (Vitamin B12)
Hazards
- Toxic
- Skin sensitizer
History
| Discovered | 1735 |
|---|---|
| Discovered by | Georg Brandt |
| Name | From German Kobold (goblin/spirit) |