hysical characteristics that are quantized -- such as energy, charge, and angular momentum -- are of such importance that names and symbols are given to them. The values of quantized entities are expr...hysical characteristics that are quantized -- such as energy, charge, and angular momentum -- are of such importance that names and symbols are given to them. The values of quantized entities are expressed in terms of quantum numbers , and the rules governing them are of the utmost importance in determining what nature is and does. This section covers some of the more important quantum numbers and rules.