Which of the following is the correct chemical formula for the ionic compound formed between aluminum (Al) and iodine (I)?

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

Answer: (D)

Verified step by step guidance

1. Identify the charges of the ions formed by aluminum and iodine. Aluminum typically forms a +3 charge (Al^{3+}), and iodine typically forms a -1 charge (I^{-}).
2. Determine the ratio of ions needed to balance the total positive and negative charges so that the compound is electrically neutral.
3. Since aluminum has a +3 charge and iodine has a -1 charge, you need three iodide ions to balance one aluminum ion, resulting in the formula AlI_3.
4. Write the chemical formula by placing the symbol of the metal (Al) first, followed by the symbol of the nonmetal (I) with the appropriate subscript indicating the number of ions.
5. Verify that the total positive charge equals the total negative charge: (1 \\times +3) + (3 \\times -1) = 0, confirming the formula AlI_3 is correct.