What is the value of the smallest bond angle in XeCl4?

• A. 109.5^ext{o}
• B. 120^ext{o}
• C. 90^ext{o}
• D. 180^ext{o}

Answer: (C)

Verified step by step guidance

1. Identify the molecular geometry of XeCl4 by first determining the number of electron pairs around the central atom (Xe). Xenon has 8 valence electrons, and each chlorine atom contributes 1 electron, so count bonding and lone pairs.
2. Calculate the total number of electron pairs around Xe: 4 bonding pairs (from 4 Cl atoms) and 2 lone pairs, making 6 electron pairs in total.
3. Use the VSEPR theory to determine the electron pair geometry for 6 electron pairs, which is octahedral. However, the presence of 2 lone pairs changes the molecular shape to square planar.
4. Recall that in a square planar geometry, the bond angles between the bonded atoms (Cl-Xe-Cl) are 90° and 180°, while lone pairs occupy positions opposite each other to minimize repulsion.
5. Conclude that the smallest bond angle in XeCl4 corresponds to the angle between adjacent chlorine atoms, which is 90°, due to the square planar arrangement.