Answer
This general rule only applies to cations from Group 1A through 3A and for nonmetals (only) from Groups 4A though 8A. For many transition metals there are multiple oxidation states that exist and there is no way of knowing through visual inspection what charges their ions have.
Work Step by Step
This general rule only applies to cations from Group 1A through 3A and for nonmetals (only) from Groups 4A though 8A. For many transition metals there are multiple oxidation states that exist and there is no way of knowing through visual inspection what charges their ions have.
