An ionic substance is formed when oppositely charged ions link up to form an infinitely large lattice structure that can only be described in terms of unit cells.
Ionic substances may consist of billions of oppositely charged ions. Ionic substances are hard, have high melting and boiling points and do not conduct electricity in the solid state because the ions are not free in the solid state.
However, in solution or molten state, the substance conducts electricity since the ions which are the charge carriers are now mobile.
14 days is the half-life of phosphorus-32