Chemistry · Grades 9–12
Oxidation states and redox bookkeeping · Revision sheet
Balance electron accounting without confusing oxidation state with literal charge in every bond.
Learn the idea
Rules
For a neutral compound, oxidation states sum to zero; for a polyatomic ion, they sum to its charge.
Oxidation
Oxidation is an increase in oxidation state; reduction is a decrease.
Common values
Oxygen is usually −2 and hydrogen usually +1 in simple school examples, but exceptions exist.
Bookkeeping
Oxidation state is a formal electron-accounting model, not always the real charge on an atom.
Explain without looking
- In elemental O₂, what is oxygen’s oxidation state?
- Explain why oxidation and reduction occur together in a complete electron-transfer reaction.
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.