Chemistry · Grades 8–11
Ionic formulas and charge balance · Revision sheet
Find neutral ratios without assuming every metal has only one charge.
Learn the idea
Neutral formula
For a neutral ionic compound, total positive and negative charge sum to zero.
Ratios
Use the smallest whole-number ion ratio, not an arbitrary count.
Variable charge
A Roman numeral in a name such as iron(III) specifies the oxidation state in that compound.
Polyatomic ions
Treat a named polyatomic ion as a group; use brackets when more than one group is needed.
Explain without looking
- What is the total charge number of two Al³⁺ ions?
- Explain why guessing a formula from equal numbers of positive and negative ions can fail.
Further reading and review references
These are reference links, not copied exercises, institutional endorsement or proof of independent review.
Independent educational review required. Grade bands are approximate; these are not officially aligned curricula.