Production of Materials > 4. Electrochemical Methods >
Account for changes in the oxidation state of species in terms of their loss or gain of electrons
- Oxidation state: A measure of a chemical species’ degree of oxidation.
- Uncombined elements have an oxidation state of zero.
- Simple ions have an oxidation state equal to the charge on the ion.
- During displacement reactions, the oxidation states of the two metal species involved change:
- Metal elements increase their oxidation state, as they lose electrons.
- Metal ions decrease their oxidation state, as they gain electrons.
- The sum of the oxidation states for the elements in a molecule is zero.
- In most compounds:
- Hydrogen has an oxidation state of one.
- Oxygen has an oxidation state of negative two.
- Oxidation states can be used to describe electron transfer in oxidation-reduction reactions:
- Oxidation involves an increase in oxidation state.
- Reduction involves a decrease in oxidation state.