Concept:The shape of a molecule is determined by the number of electron pairs around the central atom using the Valence Shell Electron Pair Repulsion (VSEPR) theory.
Explanation:The central atom has three bonding pairs and no lone pairs of electrons.
Thus, there are exactly three regions of electron density surrounding the central atom.
According to VSEPR theory, these three electron pairs repel one another equally.
To minimize repulsion, the pairs arrange themselves as far apart as possible in a flat, triangular layout.
This arrangement is known as trigonal planar geometry.
The bond angle between the surrounding atoms is approximately
120∘.
Since there are no lone pairs, the molecular geometry is not distorted from the electron-pair geometry.
Common examples of such molecules include
BF3 and
AlCl3.
Tetrahedral, linear, and octahedral geometries require different numbers of electron regions: four, two, and six respectively.
Answer:The molecular geometry is trigonal planar, so the correct option is B.