Enter an Element Symbol (like Fe or Cl) or toggle Show All Elements to browse the full periodic table — the Oxidation States Reference returns the Element Name, its Common Oxidation States, Most Stable State, any Exceptions & Notes, and real Example Compounds to put those numbers in context.
Element Name
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Common Oxidation States
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Most Stable State
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Exceptions & Notes
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Example Compounds
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An oxidation state (or oxidation number) is a hypothetical charge that an atom would have if all its bonds were completely ionic. It helps track electron transfer in chemical reactions and is essential for understanding redox processes.
Use these rules: 1) Free elements have oxidation state 0, 2) Group 1 metals are +1, Group 2 are +2, 3) Oxygen is usually -2, hydrogen is usually +1, 4) The sum of oxidation states equals the overall charge of the compound.
Transition metals have partially filled d orbitals that can lose different numbers of electrons. This allows them to form stable compounds with various oxidation states, making them versatile in chemical bonding.
Main group elements typically follow group patterns: Group 1 (+1), Group 2 (+2), Group 17 (-1), Group 16 (-2). However, many can exhibit multiple states, especially in compounds with different electronegativities.
Oxidation states are used to name compounds, especially those with transition metals. Roman numerals in parentheses indicate the oxidation state, like Iron(III) chloride for FeCl₃, where iron has a +3 oxidation state.
Oxidation state assumes complete ionic bonding, while formal charge considers equal sharing of electrons in covalent bonds. Both are theoretical concepts used to understand electron distribution in molecules.
While whole number oxidation states are most common, fractional oxidation states can occur in compounds with multiple atoms of the same element in different environments, or in mixed-valence compounds.
Oxidation states help predict compound formulas, balance redox equations, understand electron transfer processes, name compounds correctly, and predict chemical behavior and reactivity patterns.