What will be the geometry of `XeOF_4` according to VSEPR theory ?

Options

A. Trigonal bidpyramidal
B. Square pyramidal
C. Pentagonal planar
D. Square planer

Answer

To determine the geometry of the molecule \( \text{XeOF}_4 \) according to VSEPR (Valence Shell Electron Pair Repulsion) theory, we can follow these steps:

### Step 1: Determine the central atom
The central atom in the molecule \( \text{XeOF}_4 \) is xenon (Xe).

### Step 2: Count the valence electrons
Xenon has 8 valence electrons (as it is in group 18), oxygen has 6 valence electrons, and each fluorine has 7 valence electrons. Therefore, the total number of valence electrons in \( \text{XeOF}_4 \) is calculated as follows:

\[ \text{Total valence electrons} = \text{Valence electrons of Xe} + \text{Valence electrons of O} + 4 \times \text{Valence electrons of F} \]
\[ = 8 + 6 + 4 \times 7 = 8 + 6 + 28 = 42 \text{ electrons} \]

### Step 3: Determine the number of bonding pairs and lone pairs
In \( \text{XeOF}_4 \):
- Xenon forms 4 bonds with the 4 fluorine atoms.
- Xenon forms 1 bond with the oxygen atom.

This gives a total of 5 bonding pairs. Since xenon has 8 valence electrons and 5 are used for bonding, the remaining electrons are:

\[ 8 - 5 = 3 \text{ electrons} \]

These 3 electrons form 1 lone pair (as 2 electrons form a lone pair and 1 remains unpaired).

### Step 4: Calculate the steric number
The steric number is calculated as the sum of the number of bonding pairs and lone pairs around the central atom:

\[ \text{Steric number} = \text{Number of bonding pairs} + \text{Number of lone pairs} = 5 + 1 = 6 \]

### Step 5: Determine the geometry using VSEPR theory
According to VSEPR theory, a steric number of 6 corresponds to an octahedral arrangement. However, since there is one lone pair, the geometry will be derived from the octahedral shape. The presence of one lone pair will distort the shape to a square pyramidal geometry.

### Conclusion
Thus, the geometry of \( \text{XeOF}_4 \) according to VSEPR theory is **square pyramidal**.