Cobalt (Co)

Cobalt is a chemical element with symbol Co and atomic number 27. Like nickel, cobalt is found in the Earth's crust only in chemically combined form, save for small deposits found in alloys of natural meteoric iron.

Atomic Number

27

Atomic Mass

58.933 u

Category

transition metal

Phase

solid

Density

8.9 g/cm³

Electron Shells

2, 8, 15, 2

Atomic Structure

Protons: 27 • Electrons: 27 • Neutrons: Varies by isotope

Electron Configuration: 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d⁷

Discovery

1735 • Georg Brandt