Which of the following best describes the electron domain geometry and molecular geometry of the ion ICl4−?

• A. Electron domain geometry: trigonal bipyramidal; Molecular geometry: seesaw
• B. Electron domain geometry: octahedral; Molecular geometry: square planar
• C. Electron domain geometry: tetrahedral; Molecular geometry: trigonal pyramidal
• D. Electron domain geometry: square pyramidal; Molecular geometry: square pyramidal

Answer: (B)

Verified step by step guidance

1. Determine the total number of valence electrons for the ICl4⁻ ion. Start by adding the valence electrons from iodine (I), chlorine atoms (Cl), and the extra electron due to the negative charge.
2. Draw the Lewis structure for ICl4⁻ by placing iodine as the central atom and surrounding it with four chlorine atoms. Use the total valence electrons to form bonds and assign lone pairs, ensuring the octet rule is satisfied where applicable.
3. Count the total number of electron domains (bonding pairs + lone pairs) around the central iodine atom. This will help identify the electron domain geometry using the VSEPR theory.
4. Use the number of electron domains to determine the electron domain geometry. For example, 6 electron domains correspond to an octahedral geometry.
5. Identify the molecular geometry by considering the positions of the atoms only (ignoring lone pairs). For example, if there are 2 lone pairs and 4 bonding pairs in an octahedral arrangement, the molecular geometry is square planar.