1. Identify the Ions

* Copper(II): This tells us the copper ion has a +2 charge (Cu²⁺).

* Phosphate: This is the polyatomic ion PO₄³⁻.

2. Determine the Ratio

* To balance the charges, you need three copper(II) ions (3 x +2 = +6) and two phosphate ions (2 x -3 = -6).

3. Write the Formula

The formula for copper(II) phosphate is Cu₃(PO₄)₂.

Explanation of the Formula

* Cu₃: This indicates there are three copper atoms.

* (PO₄)₂: This indicates there are two phosphate groups, each containing one phosphorus atom and four oxygen atoms.

Key Points

* Roman numerals: The Roman numeral "II" in copper(II) indicates its oxidation state, which is +2.

* Polyatomic ions: Phosphate (PO₄³⁻) is a polyatomic ion, meaning it's a group of atoms that act as a single unit with a charge.

* Balancing charges: Chemical formulas are written to ensure that the overall charge of the compound is neutral.