Redox, which is shorthand for reduction-oxidation, is a type of chemical reaction classified by the net transfer of electrons. In this reaction, one molecule loses electrons, called oxidation, and the other molecule gains electrons, called reduction.
To help you differentiate between the two, remember the phrase 'OIL-RIG', which stands for 'oxidation is losing, reduction is gaining'. The molecule that is oxidized is called the reducing agent because it reduces the other reactant. Similarly, the molecule that is reduced is called the oxidizing agent because it oxidizes the other molecule.
Now that we have the terminology sorted out, let's look at an example of a redox reaction, the formation of the mineral magnesium oxide. During the reaction, each magnesium atom loses two electrons. Thus, magnesium is oxidized. Each oxygen atom gains two electrons; thus, oxygen is reduced.
However, not all reactions are redox reactions. For example, the reaction of calcium oxide with carbon dioxide to form calcium carbonate is not a redox reaction. So, how can we identify a redox reaction?
To do this, we track the oxidation number of each element as it goes from reactant to product. The oxidation n
