How do you write phosphide containing ion?

Answer 1

P3- This is the phosphide ion, but it is not stable in water, only with 3H in PH3 (comparable with ammonia NH3) or with some metal ions (eg. Li3P, Ca3P2, AlP) it is found as pure substance. There are also other form with negatively charged phosphorous in it.

Answer 2

To write the ion of a phosphide-containing species, you would typically indicate the charge of the phosphorus, which is usually -3. For example, the ion for phosphide would be P3-, or you can write it as phosphide ion.