Which of the following statements correctly describes the Lewis dot structure of the IBr5 molecule?

• A. The central iodine atom is surrounded by four bromine atoms and two lone pairs.
• B. The central bromine atom is surrounded by five iodine atoms and one lone pair.
• C. The central iodine atom is surrounded by five bromine atoms and one lone pair.
• D. The central iodine atom is surrounded by five bromine atoms and no lone pairs.

Answer: (C)

Verified step by step guidance

1. Identify the central atom in the IBr5 molecule. Since iodine (I) is less electronegative than bromine (Br), iodine will be the central atom.
2. Determine the total number of valence electrons. Iodine has 7 valence electrons, and each bromine atom has 7 valence electrons. For IBr5, total valence electrons = 7 (I) + 5 × 7 (Br) = 42 electrons.
3. Draw single bonds between the central iodine atom and each of the five bromine atoms. Each bond uses 2 electrons, so 5 bonds use 10 electrons.
4. Distribute the remaining electrons to satisfy the octet rule for the bromine atoms first. Each bromine needs 6 more electrons (3 lone pairs) to complete its octet, so 5 bromines × 6 electrons = 30 electrons used.
5. Assign the leftover electrons to the central iodine atom as lone pairs. After bonding and completing bromine octets, iodine will have one lone pair remaining, consistent with an expanded octet.