Which of the following best describes the electron domain geometry and molecular geometry of the neutral compound IF₃ based on its Lewis structure?

• A. Electron domain geometry: trigonal bipyramidal; Molecular geometry: T-shaped
• B. Electron domain geometry: tetrahedral; Molecular geometry: trigonal planar
• C. Electron domain geometry: trigonal planar; Molecular geometry: linear
• D. Electron domain geometry: octahedral; Molecular geometry: square planar

Answer: (A)

Verified step by step guidance

1. Draw the Lewis structure of IF₃ by first counting the total valence electrons: Iodine (I) has 7 valence electrons and each Fluorine (F) has 7 valence electrons, so total electrons = 7 + 3 × 7 = 28 electrons.
2. Place the iodine atom in the center and arrange the three fluorine atoms around it, then form single bonds between iodine and each fluorine, using 6 electrons (3 bonds × 2 electrons each).
3. Distribute the remaining electrons as lone pairs to satisfy the octet rule, placing lone pairs on the fluorine atoms first, then placing any leftover electrons as lone pairs on the iodine atom.
4. Determine the electron domain geometry by counting the total regions of electron density (bonding pairs + lone pairs) around the central iodine atom. For IF₃, this total is 5 regions, which corresponds to a trigonal bipyramidal electron domain geometry.
5. Determine the molecular geometry by considering only the positions of atoms (ignoring lone pairs). With 3 bonding pairs and 2 lone pairs on iodine, the molecular geometry is T-shaped.