An oxidation number (state) is a number assigned to an atom that represents the apparent charge it would carry if the electrons in each of its bonds were given entirely to the more electronegative atom. It is a bookkeeping device used to track the transfer of electrons in redox reactions. A change in an atom's oxidation number signals that it has been oxidised or reduced.

氧化数(氧化态)是赋予原子的一个数值,表示假设其每个键中的电子都完全归于电负性更大的原子时,该原子会带的表观电荷。它是用于追踪氧化还原反应中电子转移的记账工具。原子氧化数的变化表明它已被氧化或被还原。