What is the bond angle for a trigonal planar molecular shape?

In a trigonal planar molecular shape, the arrangement of atoms around the central atom is such that they are positioned at the corners of an equilateral triangle. This geometric configuration allows for optimal spacing between the atoms due to electron repulsion, which is a key principle in molecular geometry.

As a result, the bond angle in a trigonal planar molecule is 120 degrees. This angle minimizes the repulsive forces between the bonding pairs of electrons, stabilizing the structure. The trigonal planar shape is typically found in molecules with three regions of electron density surrounding the central atom, where all of these regions are involved in bonding with other atoms. The flat, 2D structure contributes to the 120-degree bond angle characteristic of this molecular shape.

The other choices reflect angles associated with different molecular geometries; for example, the 109.5 degrees bond angle is associated with a tetrahedral geometry, commonly seen when there are four regions of electron density, such as in methane (CH₄). Understanding these distinctions helps clarify the conformations adopted by various molecules based on the arrangement and number of electron pairs around the central atom.