Which of the following molecules has a trigonal bipyramidal electron geometry but a T-shaped molecular geometry?

• A. ClF3
• B. PF5
• C. SF4
• D. BrF5

Answer: (A)

Verified step by step guidance

1. Step 1: Understand the difference between electron geometry and molecular geometry. Electron geometry considers all electron groups (bonding and lone pairs) around the central atom, while molecular geometry considers only the positions of the atoms (bonding groups).
2. Step 2: Recall that a trigonal bipyramidal electron geometry corresponds to a central atom with five regions of electron density (bonding or lone pairs). This geometry has two axial positions and three equatorial positions.
3. Step 3: Analyze each molecule's Lewis structure to determine the number of bonding pairs and lone pairs on the central atom. For example, PF5 has five bonding pairs and no lone pairs, so its molecular geometry is also trigonal bipyramidal.
4. Step 4: Identify molecules with three bonded atoms and two lone pairs on the central atom, which leads to a T-shaped molecular geometry within a trigonal bipyramidal electron geometry. This is because the two lone pairs occupy equatorial positions, and the three bonded atoms occupy two axial and one equatorial positions.
5. Step 5: Confirm that ClF3 fits this description: it has five electron groups (trigonal bipyramidal electron geometry) with two lone pairs and three bonded atoms, resulting in a T-shaped molecular geometry.