Oxidation-Reduction (Redox) Reactions

Ever heard "LEO says GER"? It's a handy way to remember that Loss of Electrons is Oxidation, while Gain of Electrons is Reduction. In every redox reaction, one substance gives up electrons (gets oxidized) while another takes them (gets reduced).

The oxidation state or number shows how many electrons an atom loses or gains in a reaction. When this number increases, the atom is oxidized; when it decreases, it's reduced. Some quick rules to remember: free atoms have an oxidation state of 0, hydrogen is usually +1, and oxygen is typically -2.

Redox reactions come in several types, including combination $A + B → AB$, decomposition $AB → A + B$, replacement (AB + C → A + BC), and combustion reactions. When balancing these reactions, we break them into two half-reactions - one showing oxidation and one showing reduction.

Tip: When solving redox problems, always start by identifying which atoms change oxidation numbers. Those are your key players in the electron exchange!

To write balanced net ionic equations for redox reactions, follow these steps: write the unbalanced equation first, assign oxidation numbers to each atom, separate the half-reactions showing electron transfer, then balance both atoms and charge on both sides of the equation.