What is an ion and how is it formed?

Ions are an atom or molecule with a net electric charge due to the loss or gain of one or more electrons. They are formed when atoms lose or gain electrons in order to fulfill the octet rule and have full outer valence electron shells.

Explanation:

When they lose electrons, they become positively charged and are named cations. When they gain electrons, they are negatively charged and are named anions.

dynamic equilibrium is the answer.