Predict the chemical formula for the ionic compound formed by aluminum (Al) and chlorine (Cl).

• A. Al2Cl3
• B. AlCl
• C. AlCl3
• D. Al3Cl2

Answer: (C)

Verified step by step guidance

1. Identify the charges of the ions formed by each element: Aluminum (Al) typically forms a +3 charge (Al^{3+}), and chlorine (Cl) typically forms a -1 charge (Cl^{-}).
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 chlorine has a -1 charge, you need three chloride ions to balance one aluminum ion, because 1 \times (+3) + 3 \times (-1) = 0.
4. Write the chemical formula by placing the symbol of aluminum first, followed by the symbol of chlorine with the appropriate subscript to indicate the number of chloride ions: AlCl_{3}.
5. Verify that the total positive and negative charges balance to zero, confirming the formula represents a neutral ionic compound.