Final answer:
To find the ratio of ions in an ionic compound, use the crisscross method to cross the charges of the ions and simplify the subscripts to the simplest whole-number ratio that results in electrical neutrality.
Step-by-step explanation:
To find the ratio of ions in ionic compounds, we use the crisscross method which involves crossing over the charges of the ions to determine the subscript of the opposite ion. This process is critical because ionic compounds must be electrically neutral, meaning the total number of positive charges on cations must equal the total number of negative charges on anions. Hence, the correct way to find the ratio is:
- Write the cation and anion along with their respective charges.
- Cross the charges, taking the absolute value of the charge on one ion as the subscript for the other ion.
- Simplify the resulting subscripts to the lowest whole-number ratio that maintains electrical neutrality.
- Write the final chemical formula without including any subscript that is 1.
This crisscross method ensures that the resulting chemical formula represents the simplest whole-number ratio of ions that results in a neutral compound. For example, the compound aluminum oxide has a formula of Al2O3, indicating two aluminum cations (Al3+) for every three oxide anions (O2-).