When zinc ions (Zn²⁺) and phosphate ions (PO₄³⁻) combine to form a compound, we need to balance the charges of the ions. Zinc has a +2 charge, while phosphate has a -3 charge. To form a neutral compound, we can find the lowest common multiple of the charges, which is 6.
To achieve this, we need 3 zinc ions (3 x +2 = +6) and 2 phosphate ions (2 x -3 = -6). Combining these ions, we get:
Zn₃(PO₄)₂
Therefore, the formula for the compound formed by Zn²⁺ and PO₄³⁻ is Zn₃(PO₄)₂. This indicates that the compound consists of three zinc ions for every two phosphate ions, resulting in a neutral overall charge.