What is the formula for the compound that forms when magnesium bonds with phosphorus?

1 Answer
Jan 24, 2017


The formula would be #Mg_3P_2#. This would be an ionic compound.


First, we know this is an ionic compound because one of the elements is a metal.

From the periodic table or from the valence shells of the atoms, we can determine that magnesium forms an ion of #+2# charge. Also, phosphorus will form a #-3# ion.

The formula is based on combining these ions in the smallest ratio that results in a total charge of zero, because all compounds must be electrically neutral.

So, three #Mg^(2+)# ions and two #P^(3-)# ions result in a total of +6 and -6 charges, which gives us the zero total charge.

A compound with three magnesium ions and two phosphorus ions would be written #Mg_3P_2#