Write the correct ionic formula for the compound formed between each of the following pairs of ions:e. Al³⁺ and S²⁻

Verified step by step guidance

1. Identify the charges of the ions: Al has a charge of +3 (Al^{3+}) and S has a charge of -2 (S^{2-}).
2. To form a neutral compound, the total positive charge must equal the total negative charge.
3. Determine the least common multiple of the charges: The least common multiple of 3 and 2 is 6.
4. Calculate the number of each ion needed to balance the charges: You need 2 Al^{3+} ions to get a total positive charge of +6, and 3 S^{2-} ions to get a total negative charge of -6.
5. Write the formula by placing the number of each ion as subscripts: The formula is Al_{2}S_{3}.

Key Concepts

Ionic Compounds

Ionic compounds are formed when positively charged ions (cations) and negatively charged ions (anions) bond together through electrostatic forces. The overall charge of the compound must be neutral, meaning the total positive charge must balance the total negative charge. Understanding how to combine these ions based on their charges is essential for writing correct ionic formulas.

Charge Balance

Charge balance is a fundamental principle in forming ionic compounds. Each ion has a specific charge, and when combining ions, the total positive charge from cations must equal the total negative charge from anions. For example, in the case of Al³⁺ (with a +3 charge) and S²⁻ (with a -2 charge), the charges must be balanced to determine the correct ratio of ions in the formula.

Chemical Formula Notation

Chemical formula notation is a way to represent the composition of a compound using symbols and numbers. In ionic compounds, the formula is written with the cation first followed by the anion, and subscripts are used to indicate the number of each ion needed to achieve charge balance. For Al³⁺ and S²⁻, the correct formula is Al₂S₃, indicating two aluminum ions and three sulfide ions combine to form a neutral compound.