What is the geometry of the IBr2^- ion? — Chemical Bonding Chemistry Question

💡 Solution & Explanation

Step 1: Determine the steric number for the central Iodine in IBr2^-: Iodine has 7 valence electrons, plus 1 for the negative charge = 8. Two form single bonds with Bromine, leaving 6 electrons (3 lone pairs). Steric number = 2 bond pairs + 3 lone pairs = 5. Step 2: For a steric number of 5, the geometry of the electron domains is trigonal bipyramidal. Step 3: To minimize repulsions, the three lone pairs occupy the equatorial positions, leaving the two Bromine atoms in axial positions, resulting in a linear shape (180° bond angle). This matches option (a).