Which of the following is the correct chemical formula for aluminum iodide?

• A. Al2I3
• B. Al3I2
• C. AlI
• D. AlI3

Answer: (D)

Verified step by step guidance

1. Identify the charges of the ions involved: aluminum typically forms a +3 charge (Al^{3+}), and iodide forms a -1 charge (I^{-}).
2. Determine the ratio of ions needed to balance the overall charge so that the compound is electrically neutral.
3. Since aluminum has a +3 charge and iodide has a -1 charge, you need three iodide ions to balance one aluminum ion.
4. Write the chemical formula by placing the number of each ion as subscripts: one aluminum ion and three iodide ions, resulting in AlI_{3}.
5. Verify that the total positive charge (+3 from Al) balances the total negative charge (3 × -1 from I), confirming the formula AlI_{3} is correct.