The point group of BrF3 is C2v. Draw the structure of BrF3 and compare your answer with the predictions of the VSEPR model.
The Correct Answer and Explanation is :
The molecular structure of bromine trifluoride (BrF₃) follows the predictions made by the VSEPR (Valence Shell Electron Pair Repulsion) model, but with a few key points to consider for proper understanding.
Structure of BrF₃:
BrF₃ is an interhalogen compound in which a central bromine atom (Br) is bonded to three fluorine atoms (F). According to the VSEPR theory, the molecular geometry of BrF₃ can be predicted by considering the electron pairs around the central atom. In BrF₃, bromine has five valence electrons, and fluorine contributes one electron per bond. The electron pairs around the bromine atom include three bonding pairs (Br-F bonds) and two lone pairs of electrons, which results in a T-shaped geometry.
The lone pairs on the bromine atom cause the bonding pairs to be pushed downward, resulting in a 90° bond angle between two fluorine atoms and a 180° angle between the fluorines in the opposite direction, making the shape of the molecule similar to a “T”.
VSEPR Analysis:
- The BrF₃ molecule has a total of five electron pairs around the central atom: three bonding pairs (Br-F) and two lone pairs.
- The arrangement of these electron pairs corresponds to a trigonal bipyramidal electron geometry.
- The lone pairs occupy the equatorial positions to minimize electron-electron repulsion, leaving the fluorine atoms in the axial positions.
- The presence of lone pairs causes a distortion from a perfect trigonal bipyramidal structure to a T-shaped geometry.
- This T-shaped arrangement leads to a bond angle of about 90° between the two axial fluorine atoms.
Point Group:
The point group of BrF₃ is C₂v, as it exhibits a symmetry that includes a C₂ axis (a twofold rotation axis) passing through the central bromine atom and perpendicular to the plane of the fluorine atoms. This symmetry is consistent with the T-shaped structure, with the fluorines occupying positions around the central atom and lone pairs in the remaining space.
Thus, the VSEPR model accurately predicts the T-shaped geometry of BrF₃, and the molecule adheres to the C₂v point group due to its symmetry.