The oxidation number of H is +1 and of O is -2 in most
Last updated: 8/5/2022
The oxidation number of H is +1 and of O is -2 in most compounds. Although this statement applies to most compounds, a few important exceptions occur. • When H forms a binary compound with a metal, the metal forms a positive ion and H becomes a hydride ion, H. Thus, in CaH₂ the oxidation number of Ca is +2 (equal to the group number) and that of H is -1. Oxygen can have an oxidation number of -1 in a class of compounds called peroxides. For example, in H₂O₂, hydrogen peroxide, H is assigned its usual oxidation number of +1, and so O is -1. The algebraic sum of the oxidation numbers for the atoms in a neutral compound must be zero; in a polyatomic ion, the sum must be equal to the ion charge. For example, in HCIO, the H atom is assigned +1 and the O atom is assigned -2. This means the Cl atom must be +7. a. POCI3 Oxidation number = b. C₂O42- Oxidation number = c. HSO4- Oxidation number =