Final answer:
A t-shaped molecular shape within a trigonal bipyramidal electron pair geometry has three bonding pairs and two lone pairs, with the lone pairs positioned equatorially. This geometry creates angles that are slightly less than 180° due to LP-BP repulsions, resulting in a Faxial-Br-Faxial angle of approximately 172°.
Step-by-step explanation:
The molecular shape described as AX₃E₂ represents a molecule with three atoms attached to a central atom (A) and two lone pairs of electrons (E₂). This arrangement is known as a t-shaped molecular shape within the trigonal bipyramidal electron pair geometry. In the trigonal bipyramidal structure, there are positions known as axial and equatorial. Axial positions are above and below the plane, while equatorial positions are on the plane itself. For a t-shaped structure like BrF3, there are three bonding pairs (Br-F bonds) and two lone pairs on the central atom (Br). The lone pairs reside in the equatorial positions to minimize repulsions, leaving the bonding pairs in a T configuration.
The angles formed by the atoms in a t-shaped molecule are not the typical 90° or 120° angles found in a complete trigonal bipyramidal geometry. Due to repulsion between lone pairs and bonding pairs (LP-BP repulsions), the Faxial-Br-Faxial angle is reduced to approximately 172°, less than the ideal 180°.a