If there are five electron pairs in outer shell then structure and bond angles as predicted by Sidgwick powell theory is

Options

A. octahedron `90^@`
B. trigonal bipyramidal `120^@` and `90^@`
C. pentagonal bipyramidal `72^@` and `90^@`
D. tetrahadron `109^@28`

Answer

To determine the structure and bond angles when there are five electron pairs in the outer shell according to the Sidgwick-Powell theory, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Number of Electron Pairs**:
We start with the information that there are five electron pairs in the outer shell. This could consist of bonding pairs (sigma bonds) and lone pairs.

2. **Determine Hybridization**:
The five electron pairs suggest a hybridization state. The hybridization that corresponds to five electron pairs is typically **sp³d**. This is because:
- 5 electron pairs = 5 hybrid orbitals.

3. **Predict the Molecular Geometry**:
Based on the hybridization of sp³d, the molecular geometry can be predicted. The arrangement of five electron pairs around a central atom leads to a **trigonal bipyramidal** structure.

4. **Consider Different Scenarios**:
Depending on the distribution of bonding pairs and lone pairs, we can have different geometries:
- **5 bonding pairs**: Trigonal bipyramidal
- **4 bonding pairs and 1 lone pair**: Seesaw shape
- **3 bonding pairs and 2 lone pairs**: T-shaped
- **2 bonding pairs and 3 lone pairs**: Linear

5. **Determine Bond Angles**:
- In a **trigonal bipyramidal** structure, the bond angles are:
- 120 degrees between the equatorial positions.
- 90 degrees between the axial and equatorial positions.
- In the **seesaw** shape, the bond angles will be slightly distorted from the ideal angles due to the presence of the lone pair.
- In the **T-shaped** structure, the bond angles between the bonding pairs will be approximately 90 degrees.
- In the **linear** structure, the bond angle is 180 degrees.

### Summary of the Answer:
- The structure predicted by the Sidgwick-Powell theory for five electron pairs is **trigonal bipyramidal** when all are bonding pairs.
- The bond angles are **120 degrees** (equatorial) and **90 degrees** (axial).