Topic summary
Oxidation number
Extracted from the Wikipedia article Oxidation state.
Overview
Oxidation numbers are assigned to elements in a molecule such that the overall sum is zero in a neutral molecule. The number indicates the degree of oxidation of each element caused by molecular bonding. In ionic compounds, the oxidation numbers are the same as the element's ionic charge. Thus for KCl, potassium is assigned +1 and chlorine is assigned −1. The complete set of rules for assigning oxidation numbers are discussed in the following sections.