The name for the phosphorus ion depends on its charge:

* Phosphate ion: PO₄³⁻ (has a -3 charge)

* Phosphite ion: PO₃³⁻ (has a -3 charge)

* Hypophosphite ion: H₂PO₂⁻ (has a -1 charge)

* Phosphine ion: PH₃ (can act as a weak base, forming PH₄⁺)

Therefore, it's important to specify the charge when talking about a phosphorus ion.