How can you find an oxidation number?
You can work them out based on the following rules for oxidation states.
All uncombined elements have an oxidation number of zero:
Some elements always have the same oxidation state:
- Group 1 are +1
- Group 2 are +2
- Aluminium is +3
- Fluorine is -1
Others can be tricksy based on the compounds they are in:
- Hydrogen always +1 except in metal hydrides (like NaH) where it is -1
- Oxygen always -2, except in peroxides, superoxides, and