Which of the following is the correct chemical formula for the ionic compound formed between magnesium and iodine?

• A. Mg2I
• B. MgI2
• C. Mg2I2
• D. MgI

Answer: (B)

Verified step by step guidance

1. Identify the charges of the ions formed by magnesium and iodine. Magnesium typically forms a \(\text{Mg}^{2+}\) ion, and iodine forms a \(\text{I}^{-}\) ion.
2. Determine the ratio of ions needed to balance the total positive and negative charges so that the compound is electrically neutral.
3. Since magnesium has a charge of +2 and iodine has a charge of -1, you need two iodide ions to balance one magnesium ion.
4. Write the chemical formula by placing the magnesium ion first followed by the number of iodide ions needed, which gives \(\text{MgI}_2\).
5. Verify that the total positive charge (+2 from one \(\text{Mg}^{2+}\)) balances the total negative charge (2 × -1 from two \(\text{I}^{-}\) ions), confirming the formula is correct.