Cobalt (Co)
Cobalt (Co, element 27) is a transition metal in group 9, period 4. Atomic mass 58.933, electron configuration [Ar] 3d⁷ 4s², uses and facts.
About Cobalt
Cobalt is a transition metal with the symbol Co and atomic number 27. It is a solid at room temperature, and it sits in group 9, period 4 of the periodic table. Cobalt was discovered in 1735 by Georg Brandt.
Cobalt key facts
- Atomic number: 27
- Symbol: Co
- Atomic mass: 58.933 u
- Category: transition metal
- Group: 9
- Period: 4
- State at room temperature: solid
- Electron configuration: [Ar] 3d⁷ 4s²
- Electronegativity (Pauling): 1.88
- Melting point: 1768 K (1494.85 °C)
- Boiling point: 3200 K (2926.85 °C)
- Density: 8.9 g/cm³
- Common oxidation states: −3, −1, 0, +1, +2, +3, +4, +5
Electron configuration
The electron configuration of cobalt is [Ar] 3d⁷ 4s². The part in brackets is the noble gas core; the rest shows how the outer electrons fill their subshells.
Uses of cobalt
- Batteries
- Magnets
- Blue pigment
Did you know?
The name comes from German 'Kobold' (goblin), miners blamed goblins when cobalt ore poisoned them.
Other elements in group 9 and neighbours
Frequently asked questions
What is the atomic number of cobalt?
The atomic number of cobalt is 27, which means every cobalt atom has 27 protons.
What is the electron configuration of cobalt?
The electron configuration of cobalt is [Ar] 3d⁷ 4s².
What group and period is cobalt in?
Cobalt is a transition metal in group 9, period 4.
What state is cobalt at room temperature?
Cobalt is a solid at room temperature.
What is cobalt used for?
Cobalt is used for batteries, magnets, blue pigment.