Suprabha B.

Ions are obtained when an atom loses or gains one or more electrons.

Any element in its atomic state will have an equal number of electrons (negatively charged) and protons (positively charged) and will, therefore, be electrically neutral. However, if it gains one or more electrons, the fixed number of protons cannot balance the negative charge due to these extra electrons and thus a negatively charged ion is formed, which we call anion.

Similarly, if an atom loses one or more electrons, the total positive charge on it due to the fixed number of protons will exceed the total negative charge due to the reduced number of electrons. Thus, a positively charged ion will be formed, which we call Cation.

Example- Sodium (Na ) in its atomic state has 11 electrons and 11 protons. Thus the total positive charge of 11 units contributed by the protons balances the total negative charge of 11 units due to the electrons and is therefore electrically neutral. However, if it loses one electron, it will have 10 electrons and 11 protons. Therefore 11 units of positive charge exceed ten units of negative charge by one. It will now be called a cation (Na+). Similarly, Chlorine (Cl ) has 17 protons and 17 electrons in its neutral state, which on gaining an electron becomes 18. In such a situation, the total negative charge exceeds, and the chlorine anion is formed. (Cl-).