This theory was presented by a Swedish scientist Arrhenius in 1887. According to this theory:
1) When electrolytes are dissolved in water, they split into positive and negative ions. This process is called ionization.
2) The total positive charge is equal to the total negative charge and the solution is electrically neutral.
3) Metallic ions, ammonium ions and hydrogen ions carry positive charge while non-metallic ions and hydroxide ions carry negative charge.
4) The number of electrical charges present on any ion is equal to the valency of the atom or the radical.
5) The properties of ions are different from the properties of their related atoms.
6) Ions move in all possible directions in fused salts or in aqueous solutions of salts.
7) When electric current is passed through an electrolyte, the positive ions are attracted towards the cathode while the negative ions tend to move towards anode.