What is the molecular geometry of the BrF_2^- ion?

• A. Linear
• B. T-shaped
• C. Trigonal planar
• D. Bent

Answer: (A)

Verified step by step guidance

1. Step 1: Determine the total number of valence electrons for the BrF_2^- ion. Bromine (Br) has 7 valence electrons, each fluorine (F) has 7 valence electrons, and the negative charge adds 1 extra electron. So, total valence electrons = 7 (Br) + 2 × 7 (F) + 1 (charge).
2. Step 2: Draw the Lewis structure by placing bromine as the central atom bonded to two fluorine atoms. Use the total valence electrons to complete the octets of the fluorine atoms and place any remaining electrons as lone pairs on the bromine atom.
3. Step 3: Count the number of bonding pairs and lone pairs around the central bromine atom. This will help determine the electron pair geometry using the VSEPR (Valence Shell Electron Pair Repulsion) theory.
4. Step 4: Use the VSEPR model to predict the molecular geometry. For example, if there are three lone pairs and two bonding pairs around bromine, the electron geometry is trigonal bipyramidal, but the molecular shape depends only on the positions of atoms (bonding pairs).
5. Step 5: Based on the arrangement of bonding pairs and lone pairs, identify the molecular geometry. For BrF_2^-, with three lone pairs and two bonding pairs, the shape is linear because the lone pairs occupy equatorial positions, and the fluorine atoms are opposite each other.