How can I write the formula for sodium phosphide?

1 Answer
Jun 23, 2014

Sodium Phosphide has a formula of #Na_3P#.

Sodium is a metal cation with a charge of #Na^(+1)#
Phosphorus is a nonmetal anion with a charge of #P^(-3)#

In order to bond ionically the charges must be equal and opposite.
It will take one -3 phosphide ion to balance three +1 sodium ions forming a magnesium phosphide molecule of #Na_3P#.

I hope this was helpful.
SMARTERTEACHER