What is the co-ordination number of `Cl^(-)` in CsCl structure ?

Answer

To determine the coordination number of \( Cl^- \) in the CsCl structure, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding the CsCl Structure**:
- CsCl (cesium chloride) crystallizes in a body-centered cubic (BCC) lattice structure. In this structure, cesium ions (\( Cs^+ \)) are located at the body center, while chloride ions (\( Cl^- \)) are located at the corners of the cube.

2. **Identifying the Positions of Ions**:
- In the BCC structure, there is one \( Cs^+ \) ion at the center of the cube and 8 \( Cl^- \) ions at each of the corners of the cube.

3. **Calculating the Coordination Number**:
- The coordination number of an ion is defined as the number of nearest neighboring ions surrounding it. In the case of \( Cl^- \), it is surrounded by \( Cs^+ \) ions.
- In the BCC structure, each \( Cl^- \) ion at the corner is surrounded by 8 \( Cs^+ \) ions located at the body center and the adjacent corners.

4. **Conclusion**:
- Therefore, the coordination number of \( Cl^- \) in the CsCl structure is 8.

### Final Answer:
The coordination number of \( Cl^- \) in the CsCl structure is **8**.

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