1. Identify the ions:
* Ammonium ion: NH₄⁺
* Chromate ion: CrO₄²⁻
2. Determine the charges:
* Ammonium ion has a +1 charge.
* Chromate ion has a -2 charge.
3. Balance the charges:
* To balance the charges, we need two ammonium ions (2 x +1 = +2) for every one chromate ion.
4. Write the formula:
* The correct formula is (NH₄)₂CrO₄.
Therefore, the compound between ammonium and chromate ions is ammonium chromate, (NH₄)₂CrO₄.
