How to Calculate Oxidation States

Learn how to determine the oxidation state of atoms.
••• Hemera Technologies/ Images

The oxidation state of a molecule or compound shows the overall charge of the species being observed. Oxidation states allow a large amount of information to be inferred from a compound or ion. Information such as potential reactivity, compound composition and molecular structure can be inferred with relative accuracy given the oxidation states of one or more of the constituent species. The determination of oxidation states is often first encountered in introductory chemistry courses.

    Determine the overall charge of the compound or ion being observed. The overall charge of the entire compound is generally located in the upper-right corner of the compound name. If no charge is written, it is assumed to be a neutral compound.

    Determine the oxidation state of any species within the compound that are static. For example, oxygen, in virtually all cases, has a charge of minus 2. Fluorine is another example of a static oxidation state whose value is minus 1. Further static oxidation states are located on the periodic table by group number.

    Multiply the static oxidation states by the number of atoms found within the compound. For example, Na2SO4 has two sodium (Na) atoms with an oxidation charge of plus 1 each and an overall oxidation value of plus 2.

    Add together the oxidation values for all known species.

    Subtract the summed value from the overall charge of the compound. For example, Na2SO4, Na2 yields 2 (plus 1) + 4(minus 2) = minus 6. Subtracting minus 6 from the neutral value of 0 yields 0 - (minus 6) = 6. This final value is the oxidation state of the unknown element, in this case sulfur.

Related Articles

What Are Some Ways to Track the Valence Electrons in...
How to Find an Oxidation Number
How to Determine the Charge of Transition Metal Ions
How to Calculate the Formal Charge of CoCl2
What Are Subscripts in a Chemical Formula Used to...
Difference Between Atoms & Ions
How to Find Out If an Element Is an Ion
Non Neutral Atoms Examples
How to Know if a Substance is a Reducing Agent or...
How to Balance Redox Equations
Elements That Lose Electrons in a Reaction
What Substances Contain Polyatomic Ions?
What Happens to the Oxidation Number When an Atom in...
What Does Electronegativity Have to Do With Oxidation...
How to Know If an Element Has a Positive or Negative...
How to Figure Out Protons, Neutrons, and Electrons
How to Figure Out the Chemical Symbol for Ions
How to Count Atoms in Chemical Formulas
How to Memorize Ionic Compounds