Yes. Cobalt is a metal, classified as a transition metal on the periodic table.

How many protons does cobalt have?

Cobalt has 27 protons. Its atomic number is 27, which is also the number of electrons in a neutral atom of cobalt.

What group and period is cobalt in?

Cobalt is in group 9 and period 4 of the periodic table, in the d-block.

What is the atomic mass of cobalt?

The atomic mass of cobalt is 58.933 u (unified atomic mass units).

Element 27

Cobalt (Co)

Transition metal · Period 4 · Group 9 · d-block

Cobalt (Co) is element 27 of the periodic table, a transition metal in period 4, group 9 (d-block) with an atomic mass of 58.933 and is a solid at standard conditions.

At a glance

Atomic number: 27
Symbol: Co
Atomic mass: 58.933 u
Category: Transition metals
Period: 4
Group: 9
Block: d-block
Phase at STP: solid

Electron structure

Electron configuration: 1s2 2s2 2p6 3s2 3p6 3d7 4s2
Shorthand configuration: [Ar] 3d7 4s2
Electrons per shell: 2, 8, 15, 2
Oxidation states: -3, -1, +1, +2, +3, +4, +5

Physical properties

Melting point: 1,768 K (1,494.85 °C)
Boiling point: 3,200 K (2,926.85 °C)
Density: 8.86 g/cm³
Phase: solid

Atomic properties

Electronegativity (Pauling): 1.88
Atomic radius: 152 pm
Covalent radius: 126 pm
First ionization energy: 760 kJ/mol
Electron affinity: 64 kJ/mol

Notable isotopes

Notable isotopes of Cobalt: mass number, atomic mass, natural abundance, and stability.
Isotope	Mass	Abundance	Stability
Co-59	58.9332	100%	Stable

Common uses

Batteries
Superalloys
Blue pigments
Magnets

Discovery

Year: 1735
Discovered by: Georg Brandt
Country: Sweden

Frequently asked questions

Is cobalt a metal?: Yes. Cobalt is a metal, classified as a transition metal on the periodic table.
How many protons does cobalt have?: Cobalt has 27 protons. Its atomic number is 27, which is also the number of electrons in a neutral atom of cobalt.
What group and period is cobalt in?: Cobalt is in group 9 and period 4 of the periodic table, in the d-block.
What is the atomic mass of cobalt?: The atomic mass of cobalt is 58.933 u (unified atomic mass units).

Keep exploring

Cobalt's row is on the printable element property sheet, and its tile is on the periodic table wall chart - the same numbers as above, laid out for A4 or A3 paper.