Which of the following compounds of Xe is square pyramidal ?

Question

Accepted Answer

The question asks which of the given compounds of xenon (Xe) has a square pyramidal molecular geometry. The correct answer is Option 2: $XeOF_{4}$. Let's provide a detailed explanation to justify why this is the correct answer and why the other options are incorrect.

1. **Explanation for Option 2: $XeOF_{4}$**
   - $XeOF_{4}$ is a compound where xenon is the central atom bonded to one oxygen atom and four fluorine atoms. The molecular geometry of $XeOF_{4}$ can be understood by considering the electron pair geometry around the xenon atom.
   - Xenon has eight valence electrons. In $XeOF_{4}$, it forms five bonds (one with oxygen and four with fluorine), using five of its valence electrons. This leaves one lone pair of electrons on the xenon atom.
   - The presence of five bonding pairs and one lone pair results in a total of six electron pairs, which corresponds to an octahedral electron pair geometry. However, due to the presence of the lone pair, the molecular geometry is distorted to a square pyramidal shape.
   - Therefore, $XeOF_{4}$ has a square pyramidal geometry, making Option 2 the correct answer.

2. **Explanation for why the other options are incorrect:**

- **Option 1: $XeO_{3}$**
     - $XeO_{3}$ consists of xenon bonded to three oxygen atoms. Xenon has eight valence electrons, and in $XeO_{3}$, it forms three double bonds with oxygen, using six electrons. This leaves two lone pairs on the xenon atom.
     - The molecular geometry of $XeO_{3}$ is trigonal pyramidal, not square pyramidal, due to the presence of three bonding pairs and one lone pair.
     - Therefore, $XeO_{3}$ does not have a square pyramidal geometry.

- **Option 3: $XeF_{4}$**
     - In $XeF_{4}$, xenon is bonded to four fluorine atoms. Xenon uses four of its valence electrons to form bonds with fluorine, leaving two lone pairs.
     - The electron pair geometry is octahedral, and the molecular geometry is square planar due to the arrangement of four bonding pairs and two lone pairs.
     - Thus, $XeF_{4}$ has a square planar geometry, not square pyramidal.

- **Option 4: $XeF_{2}$**
     - $XeF_{2}$ consists of xenon bonded to two fluorine atoms. Xenon uses two of its valence electrons for bonding, leaving three lone pairs.
     - The electron pair geometry is trigonal bipyramidal, and the molecular geometry is linear due to the arrangement of two bonding pairs and three lone pairs.
     - Therefore, $XeF_{2}$ has a linear geometry, not square pyramidal.

In conclusion, $XeOF_{4}$ is the only compound among the options that exhibits a square pyramidal geometry, confirming that Option 2 is the correct answer.