Assign oxidation states to each atom in each element, ion, or compound. Cl₂, Fe³⁺, CuCl₂, CH₄, Cr₂O₇^2–, HSO₄^–

Oxidation states, or oxidation numbers, are a way to keep track of electrons in chemical compounds. They indicate the degree of oxidation of an atom in a substance, helping to determine how electrons are transferred in redox reactions. The oxidation state of an atom can be positive, negative, or zero, depending on its electron gain or loss relative to its elemental form.

There are specific rules for assigning oxidation states, such as: the oxidation state of an element in its standard state is zero, the oxidation state of a monoatomic ion equals its charge, and in compounds, hydrogen is usually +1 while oxygen is typically -2. These rules provide a systematic approach to determine the oxidation states of atoms in various compounds and ions.

Different elements have common oxidation states that they typically exhibit in compounds. For example, alkali metals usually have an oxidation state of +1, alkaline earth metals +2, and transition metals can have multiple oxidation states. Understanding these common states aids in predicting the behavior of elements in chemical reactions and helps in assigning oxidation states accurately.