Question

What is the ionic compound formula of sodium phosphate?

Answer 1

Sodium Phosphate is an ionic compound formed by two ions, Sodium $N{a}^{+}$ and Phosphate $P{O}_4^{-3}$.

In order to make a bond between them, the charges must be equal and opposite.

Therefore, it will take three $+1$ sodium ions to balance the one $-3$ phosphate ion. This will make the formula for sodium phosphate $N{a}_{3}P{O}_4$.