Which of the following is closest to the bond angle found in a molecule with trigonal pyramidal geometry?

• A. 109.5°
• B. 90°
• C. 107°
• D. 120°

Answer: (C)

Verified step by step guidance

1. Recall that the ideal bond angle for a tetrahedral electron geometry is 109.5°, which occurs when there are four regions of electron density around the central atom.
2. Understand that trigonal pyramidal geometry arises when there are three bonded atoms and one lone pair on the central atom, which is a variation of the tetrahedral electron geometry.
3. Recognize that lone pairs occupy more space than bonding pairs, causing the bonded atoms to be pushed slightly closer together, which reduces the bond angle from the ideal tetrahedral angle.
4. Therefore, the bond angle in a trigonal pyramidal molecule is slightly less than 109.5°, typically around 107°, due to the repulsion caused by the lone pair.
5. Compare the given options and identify that 107° is the closest bond angle to that found in trigonal pyramidal geometry.