Final answer:
The formula for the ionic compound barium phosphate is Ba3(PO4)2.
Step-by-step explanation:
The formula for the ionic compound barium phosphate is Ba3(PO4)2.
When writing the formula for an ionic compound, we use the charges of the ions to balance the charges. Barium is a 2+ ion (Ba²+), and phosphate is a 3¯ ion (PO¾¯).
Therefore, since the charges must balance, we need three barium ions and two phosphate ions to balance the charges, resulting in the formula Ba3(PO4)2.