Possible oxidation states of the phosphorus atom in compounds.

Phosphorus, as an element located in the fifth group, can have different oxidation states. So the highest valence of phosphorus is five, the highest valency corresponds to the group number. The lowest valence of phosphorus is three; subtract the number of the group in which the phosphorus is located from the total number of groups. So we know for sure that phosphorus can have an oxidation state of +5 and +3, as well as -3. After all, the oxidation state is similar to the valence, but the transitional oxidation state of phosphorus is +1. These are standard oxidation states for phosphorus, but compounds in which phosphorus has a more specific oxidation state are possible.