Ionic Charge vs Oxidation State

Ionic charge is the actual charge on an ion. Oxidation state is a bookkeeping value assigned to atoms in a compound.

When they match

In NaCl, sodium is Na+ and chlorine is Cl-. Their ionic charges match their oxidation states.

When they need care

In covalent molecules and oxyanions, oxidation state can be useful even when separate simple ions are not present.

How this site uses the terms

Element pages list classroom-friendly ionic charges first and warn when oxidation-state chemistry is broader.