Definition of Ion | Definition in Chemistry

                “A particle carrying either negative or positive charge, is called Ion.”

Types of Ions:

                There are following two types of ions depending upon their nature of charge.

Cation Definition:

1. The ion which has positive charge is called Cation. e.g., Na⁺¹, Ba⁺², Al⁺³ etc.
2. A Cation is formed through removal of one or more electrons from an atom.
3. Energy is required for the removal of electrons. Therefore, formation of cations is Endothermic Process.
4. A Cation may carry +1, +2 or +3 charge, depending upon the number of electrons lost.
5. A Cation which consists of more than one atom is called Molecular Cation. e.g., NH₄⁺¹, CH₃⁺¹ etc.

Anion Definition:

1. The ion which has negative charge is called Anion. e.g., Cl^-1, O^-2, N^-3 etc.
2. An Anion is formed through addition of one or more electrons to an atom.
3. Energy is released for addition of first electron, which is Therefore, Exothermic process whereas addition of second or third electrons is Endothermic Process.
4. An Anion may carry -1, -2 or -3 charge, depending upon the number of electrons added.
5. An Anion which consists of more than one atom is called Molecular Anion. e.g., OH^-1, NO₂^-1 etc.