Define reduction as a decrease in oxidation state.

In the subtopic Oxidation states, this AQA A-Level Chemistry 7405 learning objective focuses on define reduction as a decrease in oxidation state. It belongs to Oxidation, reduction and redox equations, so revision should stay anchored to this exact subtopic rather than drifting into a generic GCSE-level chemistry summary. Approved keywords to use include oxidation state, oxidation, reduction. Oxidation State. means a measure of the degree of oxidation of an atom in a substance, represented by a numerical value that can be positive, negative, or zero Avoid the mistake of students often confuse reduction with an increase in oxidation state instead of a decrease; instead, reduction is defined as a decrease in oxidation state. To clarify, remember that when an element gains electrons, its oxidation state decreases. For example, in the reaction where Fe^3+ gains an electron to become Fe^2+, the oxidation state decreases from +3 to +2, confirming that reduction has occurred For exam answers, remember that reduction is defined as a decrease in oxidation state. To identify reduction in a reaction, look for species that gain electrons, which corresponds to a decrease in their oxidation state