Oxidation state

Oxidation state is a formal charge assigned to an atom by treating each bond as fully ionic and giving bonding electrons to the more electronegative atom. It tracks electron bookkeeping, not necessarily an atom’s actual charge.

Electronegativity: Electronegativity measures how strongly an atom attracts shared electrons in a chemical bond. Bonding electrons are assigned to the more electronegative atom when oxidation states are calculated.
Chemical bond: An interaction that holds atoms or ions together through shared or transferred electrons. Oxidation-state assignment idealizes bonds as completely ionic, even when they are covalent.
Half-reaction method: A procedure for balancing redox equations by separating oxidation and reduction into half-reactions. Oxidation-state changes help identify the electron counts needed to balance each half-reaction.
Oxidation number: A formal integer or fractional value assigned to an atom by ionic electron-allocation conventions. Many texts use this as a synonym for oxidation state, though terminology can vary.
Oxidation-state rules: A set of conventions for assigning oxidation states from chemical formulas and bonding patterns. These rules operationalize the fully ionic bond assumption, including exceptions for peroxides and hydrides.
Ionic bond: An electrostatic attraction between oppositely charged ions formed through electron transfer. The fully ionic model treats every bond as if its electrons belonged to one atom.
Electrochemical cell: A device that uses redox reactions to produce electrical energy or uses electricity to drive chemical change. Electrode reactions are classified by the oxidation-state changes of their species.
Atomic charge: A charge attributed to an atom in a molecule or material, often estimated from its electron density. Oxidation state is formal bookkeeping; an atom’s physical charge need not equal it.
Formal charge: Formal charge is an atom’s bookkeeping charge when bonding electrons are divided equally between bonded atoms. Unlike oxidation state, formal charge splits shared bonding electrons equally.
Covalent bond: A bond in which atoms share one or more pairs of electrons. Real covalent sharing contrasts with oxidation states’ formal assignment of all bonding electrons to one partner.

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