How can I write the formula for magnesium phosphide?

1 Answer
Jun 23, 2014

Magnesium Phosphide has a formula of #Mg_3P_2#.

Magnesium is a metal cation with a charge of #Mg^(+2)#
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 two -3 phosphide ions to balance two +2 magnesium ions forming a magnesium phosphide molecule of #Mg_3P_2#.

I hope this was helpful.
SMARTERTEACHER