The compound magnesium phosphate has the chemical formula Mg3(PO4)2. In this compound, phosphorous and oxygen act together as one charged particle, which is connected to magnesium, the other charged particle.

Question

What does the 2 mean in the formula 5Mg3(PO4)2?

There are two elements in magnesium phosphate.
There are two molecules of magnesium phosphate.
There are two magnesium ions in a molecule of magnesium phosphate.
There are two phosphate ions in a molecule of magnesium phosphate.

Answer 1

In the formula 5Mg3(PO4)2, the "2" refers to the number of phosphate ions in a single molecule of magnesium phosphate. Therefore, the correct interpretation is:

There are two phosphate ions in a molecule of magnesium phosphate.

This means that each formula unit of magnesium phosphate contains two phosphate (PO4) ions.