What is the electronic geometry and bond angle for BH3?

The electronic geometry of BH3, or boron trihydride, is trigonal planar, which corresponds with a bond angle of approximately 120 degrees. This molecular shape arises due to the central boron atom forming three single bonds with three hydrogen atoms. Boron has three valence electrons that participate in bonding, resulting in three bonding pairs and no lone pairs on the central atom.

The arrangement of these bonding pairs to minimize electron pair repulsion leads to a planar configuration, which is characteristic of trigonal planar geometry. In this structure, each hydrogen atom is located at the corners of an equilateral triangle formed around the boron atom, perfectly demonstrating the 120-degree bond angles.

Understanding this molecular geometry is crucial because it highlights how the number of bonded atoms and the absence of lone pairs directly influence the shape and bond angles, concepts foundational to VSEPR (Valence Shell Electron Pair Repulsion) theory.