Chapter 14
Redox chemistry involves the study of reduction and oxidation reactions: Reduction refers to reactions in which a species gains electrons, while oxidation refers to those in which a species gives up or loses electrons. Since electrons can be neither created nor destroyed in normal chemical reactions (as opposed to nuclear reactions, which will be discussed in the next chapter), an isolated loss or gain of electrons cannot occur; in other words, neither oxidation nor reduction can occur all by itself. Each occurs simultaneously in a redox reaction, resulting in net electron transfer between the species. The electrons released during oxidation are taken up in the reduction process. The species undergoing reduction is said to be reduced when it gains electrons; a reduced species is also called an oxidizing agent because it causes something else (the species giving up the electrons) to be oxidized. Similarly, a reducing agent causes another species to be reduced, and is itself oxidized. This is summarized in Table 14.1 below:
| Oxidizing Agent | Reducing Agent |
| Gains electrons | Loses electrons |
| Also known as a reduced species | Also known as an oxidized species |
| Oxidation number decreases | Oxidation number increases |