How many electrons does cobalt lose/donate?

Cobalt lose 3 electrons and donate 12 electrons.

Explanation:

In the periodic table,cobalt has nine electrons .It has lost 3 electrons,so it is only six left.Once it forms the complex,each ammonia donates a pair of electrons.

each chemical family is represented as a group or column on the periodic table. based on chemical properties, there are 6 types of chemical families. group 1 represents alkali metals, group 2 represents alkaline earth metals, groups 3 to 12 represent transition metals, groups 13 to 16 represent non-metals and other metals, group 17 represents halogens and group 18 represents noble gases.