A sigma bond may be formed by the overlap of two atomic orbitals of atoms A and B. If the bond is formed along the `x-` axis, which of the following overlaps is acceptable ?

Options

A. s orbital of A and pz
orbital of B
B. px
orbital of A and py
orbital of B
C. pz
orbital of A and Px
orbital of B
D. px orbital of A and s orbital of B

Explanation

To determine which overlaps are acceptable for the formation of a sigma bond along the x-axis, we need to analyze the given options based on the characteristics of atomic orbitals.

### Step-by-Step Solution:

1. **Understanding Sigma Bonds**:
- A sigma bond is formed by the head-on (axial) overlap of atomic orbitals. This means that the orbitals must be aligned along the axis of the bond, which in this case is the x-axis.

2. **Identifying Relevant Orbitals**:
- The atomic orbitals involved in the bond formation can be s or p orbitals.
- The p orbitals are designated as Px, Py, and Pz, which are oriented along the x, y, and z axes respectively.

3. **Analyzing Each Option**:
- **Option A**: S orbital of A and Pz orbital of B.
- The s orbital is spherical and can overlap with any orbital. However, Pz is aligned along the z-axis, which does not align with the x-axis.
- **Conclusion**: Not acceptable.

- **Option B**: Px orbital of A and Py orbital of B.
- The Px orbital is aligned along the x-axis, but the Py orbital is aligned along the y-axis.
- **Conclusion**: Not acceptable.

- **Option C**: Pz orbital of A and Px orbital of B.
- The Pz orbital is aligned along the z-axis, while the Px orbital is along the x-axis.
- **Conclusion**: Not acceptable.

- **Option D**: Px orbital of A and S orbital of B.
- The Px orbital is aligned along the x-axis, and the s orbital, being spherical, can overlap in any direction.
- **Conclusion**: Acceptable.

4. **Final Answer**:
- The only acceptable overlap for forming a sigma bond along the x-axis is **Option D: Px orbital of A and S orbital of B**.