8.2—The oxidation number of elements in compounds and ions

Be able to calculate the oxidation number of elements in compounds and ions, including in peroxides and metal hydrides.

Use —the oxidation number of elements in compounds and ions to connect the rule to the data and decision in the question.

This matters because —the oxidation number of elements in compounds and ions determines what can be inferred or chosen; begin with the stated conditions and keep the conclusion tied to the evidence.

Example: apply —the oxidation number of elements in compounds and ions to one small, clearly defined case, show the key step or comparison, and explain the result in words.

Boundary: —The oxidation number of elements in compounds and ions is not a universal recommendation. Check the syllabus scope, assumptions, units and the limits of the evidence before generalising.