there must be free-moving electrons in a compound to conduct electricity.
in solid ionic compounds, there are no free electrons so it can't conduct electricity.
But in aqueous form the forces of attraction are broken and the ions (cations and anions) are free to move. This means there are free electrons that allow the aqueous compound to conduct electricity.
When an atom of the unstable isotope Na-24 decays, it becomes an atom of Mg-24 because the Na-24 atom spontaneously releases (2) a<span> beta particle</span>.