Question

The molecules having square pyramidal geometry are:

• A. BrF$_5$ & XeOF$_4$
• B. SbF$_5$ & XeOF$_4$
• C. BrF$_5$ & PCl$_5$
• D. SbF$_5$ & PCl$_5$

Hint:

Understanding electron domain geometry and molecular geometry through VSEPR theory can predict and explain the shapes of complex molecules.

Answer 1

The Correct Option is A

Let's determine the geometry of each molecule:

1. $ BrF_5 $: Bromine has 7 valence electrons. In $ BrF_5 $, there are 5 bond pairs and 1 lone pair. This gives a steric number of 6, which corresponds to an octahedral electron geometry. With 5 bonding pairs and 1 lone pair, the molecular geometry is square pyramidal.

2. $ XeOF_4 $: Xenon has 8 valence electrons. In $ XeOF_4 $, there is one double bond to oxygen and four single bonds to fluorine. There is also one lone pair. This results in a steric number of 6, corresponding to octahedral electron geometry. With 5 bonding pairs and 1 lone pair, the molecular geometry is also square pyramidal.

3. $ SbF_5 $: Antimony has 5 valence electrons. In $ SbF_5 $, there are 5 bond pairs and no lone pairs. The steric number is 5, which corresponds to a trigonal bipyramidal electron and molecular geometry.

4. $ PCl_5 $: Phosphorus has 5 valence electrons. In $ PCl_5 $, there are 5 bond pairs and no lone pairs. The steric number is 5, which corresponds to a trigonal bipyramidal electron and molecular geometry.

Conclusion: Among the given molecules, only $ BrF_5 $ and $ XeOF_4 $ have square pyramidal geometry.

Final Answer:
The final answer is $ BrF_5\ \&\ XeOF_4 $.

Answer 2

Step 1: Understand the question.
We are asked to identify which molecules among the given options have a square pyramidal geometry. The geometry of a molecule depends on the number of bonding pairs and lone pairs present on the central atom, which can be determined using the VSEPR (Valence Shell Electron Pair Repulsion) theory.

Step 2: Recall the VSEPR theory concept.
According to VSEPR theory, the geometry of a molecule depends on the total number of electron pairs (bonding + lone pairs) surrounding the central atom. A square pyramidal geometry corresponds to 6 electron pairs (AX₅E type), where five are bonding pairs and one is a lone pair.

Step 3: Analyze each molecule.
(a) BrF₅:
The central atom is bromine (Br).
- Valence electrons on Br = 7
- It forms 5 bonds with fluorine atoms, using 5 of its valence electrons.
- Remaining 2 electrons constitute one lone pair.
Therefore, BrF₅ has 6 regions of electron density (5 bonding pairs + 1 lone pair).
Hence, its molecular geometry is square pyramidal.

(b) XeOF₄:
The central atom is xenon (Xe).
- Valence electrons on Xe = 8
- It forms 1 bond with oxygen and 4 bonds with fluorine, using 5 pairs for bonding.
- One lone pair remains on Xe.
Hence, XeOF₄ also has 6 regions of electron density (5 bonding pairs + 1 lone pair).
Thus, it has a square pyramidal geometry.

(c) Check for others (if any).
Other possible molecules such as SF₄ or ClF₅ have different arrangements (seesaw and square pyramidal respectively), but based on the given choices, only BrF₅ and XeOF₄ fit the condition of AX₅E type geometry.

Step 4: Conclusion.
The molecules that exhibit square pyramidal geometry are:
BrF₅ and XeOF₄.

Final Answer:
BrF₅ and XeOF₄