1970年国际纯粹和应用化学协会(IUP-AC)给与氧化数一个严格明确的定义:在分子离子中,假设形成每一个化学键的电子都分配给电负性较大的成键原子,这样计算出的原子的电荷数就称为该元素的氧化数。如此定义氧化数,既包括了过去已经明确的由离子键联系的离子中原子的氧化数,也包括了分子、离子中由共价键联系的原子的氧化数。这样对有离子参与的氧化还原反应以 In 1970 IUP-AC gave a strictly defined definition of oxidation number: In molecular ions, it is assumed that the electrons forming each chemical bond are assigned to the electronegative bonding atoms such that The calculated charge of the atom is called the oxidation number of the element. The number of oxidation is defined as including both the oxidation number of the atoms in the ions that have been clearly defined in the past by ionic bonds and the oxidation number of the atoms in the ions, which are covalently linked. This ion-involved redox reactions