Assigning Oxidation Numbers General rules for assigning oxidation numbers (order matters!) 1. The oxidation state of each atom in an elemental substance is zero. 2. Fluorine is-1 3. Group 1A metals are +1, Group 2A metals are +2, Group 3A (except TI) and 3B are +3 in their compounds 4. Hydrogen is +1 5. Oxygen is -2 6. Halogens are-1 except when bound to a more electronegative halogen. 4. Assign an oxidation number to chlorine in each of the following substances. Substance: HCIO4 MgClh Cl2 HOCI HC Ox Number of Cl: Pre-Recitation 10-Page 3 of 4