What formula represents strontium phosphate?
The metal ion Strontium has an ionic charge of +2,
The polyatomic ion Phosphate has an ionic charge of -3,
In order for the ionic molecule strontium phosphate to form a bond the charges need to be equal and opposite.
Therefore, we will need 3 strontium ions
for a total ionic charge of +6
to bond with 2 phosphate ions
for a total ionic charge of -6
to form the molecule