Question

Bromine trifluoride auto ionizes into BrF\(_2^+\) and BrF\(_4^-\). The geometry of these ions respectively are:

• A. Linear , square planar
• B. Bent , square planar
• C. Bent , see-saw
• D. Linear , tetrahedral

Answer 1

The Correct Option is B

Step 1: Understanding the Question:
Determine the geometry (shape) of the ions formed by the auto-ionization of $BrF_3$ using VSEPR theory.
Step 2: Key Formula or Approach:
Steric Number (SN) = $\frac{1}{2}$ [Valence e$^-$ on central atom + Monovalent atoms - cation charge + anion charge]
Step 3: Detailed Explanation:
For $BrF_2^\oplus$ :
SN = $\frac{1}{2} [7 + 2 - 1] = 4$.
Hybridization = $sp^3$.
Bond pairs = 2, Lone pairs = 4 - 2 = 2.
Electron geometry = Tetrahedral; Molecular geometry = Bent (or V-shaped).

For $BrF_4^\ominus$ :
SN = $\frac{1}{2} [7 + 4 + 1] = 6$.
Hybridization = $sp^3d^2$.
Bond pairs = 4, Lone pairs = 6 - 4 = 2.
In an octahedral arrangement, two lone pairs stay at opposite (trans) positions to minimize repulsion.
Molecular geometry = Square planar.
Step 4: Final Answer:
The geometries are bent and square planar respectively.