The number of valence electrons in cobalt is two. This means two electrons are found in the outermost shell of a single atom of cobalt.
Cobalt is a transition metal that does not follow the octet rule. Its final elemental configuration is 3d7 4s2. While a d orbital can hold up to 10 electrons, less energy is required to fill the 4s orbital.
Cobalt-60 is an isotope used in the treatment of cancer. Cobalt is also used in manufacturing and design industries due to its distinct blue appearance.
The cobalt atom was discovered by the Swedish chemist Georg Brandt in 1739 as he attempted to show that the blue shades found in many types of glass were not due to the presence of bismuth.