Atomic number 27
Cobalt
Transition metal
In the real world
Quick facts
- Atomic mass
- 58.933
- Group
- 9
- Period
- 4
- State (STP)
- solid
- Electronegativity
- 1.88
- Common ox. states
- +2, +3
Properties
Electron configuration
[Ar] 3d⁷ 4s²
- Ionization energy
- 760.4 kJ/mol
- Electron affinity
- 63.7 kJ/mol
- Melting point
- 1768.00 K (1494.8 °C)
- Boiling point
- 3200.00 K (2926.8 °C)
How dangerous is it?
2/5 · Caution
The solid metal is low hazard. The caution is its dust and fume, which can irritate the lungs, cause allergies, and are studied as a possible cancer risk.
- ToxicBuilds up over time
Breathing cobalt dust or fume over time can harm the lungs, trigger allergies, and is studied as a possible cancer risk. (the dust and fume, not the solid metal)
The dust and fume are controlled with ventilation and dust masks; the solid metal is left as a solid.
How it bonds
Cobalt usually shows +2, sometimes +3. Co²⁺ in water is pink; many cobalt(II) chloride compounds shift between pink and blue with humidity (the "humidity indicator" trick). Cobalt-60 is a common medical / industrial gamma source.
