When the number of electron pairs on the central atom is six, the geometry of the molecule is :

Options

A. Octahedral
B. Trigonal bipyramidal
C. Equilateral triangle
D. Linear

Answer

To determine the geometry of a molecule when the number of electron pairs on the central atom is six, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Number of Electron Pairs**:
- We are given that the number of electron pairs on the central atom is six.

2. **Understand Electron Pairs**:
- Electron pairs can be classified into two types:
- **Lone pairs**: Non-bonding pairs of electrons.
- **Bond pairs**: Electrons that are shared between atoms in a bond.

3. **Calculate the Steric Number**:
- The total number of electron pairs (lone pairs + bond pairs) is known as the **steric number**.
- Here, the steric number is 6.

4. **Determine Hybridization**:
- The hybridization corresponding to a steric number of 6 is **sp³d²**.
- This hybridization indicates the mixing of one s orbital, three p orbitals, and two d orbitals.

5. **Identify Molecular Geometry**:
- For a central atom with sp³d² hybridization, the molecular geometry is **octahedral**.
- This means that the arrangement of the electron pairs around the central atom forms an octahedron.

6. **Example**:
- A common example of a molecule with this geometry is **SF₆** (sulfur hexafluoride).
- In SF₆, sulfur is the central atom with six bond pairs and no lone pairs, confirming the octahedral geometry.

### Conclusion:
- Therefore, when the number of electron pairs on the central atom is six, the geometry of the molecule is **octahedral**.

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