Q. Why electrolytes form ions but non-electrolytes do not?
Ans: This depends upon the nature of the compounds. All ionic compounds in their molten state or dissolved form are electrolytes because these are formed by complete transfer of electron and thus there is no orbital overlap between the bonded atoms. When these are melted or dissolved, the ions (cations, anions) get free. These ions move towards the anode and cathode in order to be oxidized or reduced.
Among the covalent compounds, the non-polar are non-conductor of
electricity while the polar covalent compounds conduct electricity when
dissolved in polar solvent. For example HCl gives H+ ions in water
and thus conduct electricity.