Each unit cell of NaCl consists of 4 chloride ions and

Options

A. `13 Na^(+)` ions
B. `4 Na^(+)` ions
C. `6 Na^(+)` ions
D. `8 Na^(+)` ions

Answer

To solve the question regarding the composition of a unit cell of NaCl, we need to analyze the structure of NaCl and how the ions are arranged within the unit cell.

### Step-by-Step Solution:

1. **Understanding the Structure of NaCl**:
- Sodium chloride (NaCl) crystallizes in a face-centered cubic (FCC) structure. In this structure, both sodium (Na⁺) and chloride (Cl⁻) ions are arranged in a specific manner.

2. **Counting Chloride Ions**:
- In the FCC unit cell, chloride ions (Cl⁻) are located at the corners and the face centers of the cube.
- Each corner of the cube contributes 1/8 of a Cl⁻ ion to the unit cell, and there are 8 corners in a cube. Therefore, the contribution from the corners is:
\[ 8 \text{ corners} \times \frac{1}{8} = 1 \text{ Cl}^- \]
- The face centers contribute 1/2 of a Cl⁻ ion each, and there are 6 faces. Thus, the contribution from the face centers is:
\[ 6 \text{ faces} \times \frac{1}{2} = 3 \text{ Cl}^- \]
- Adding these contributions together gives:
\[ 1 + 3 = 4 \text{ Cl}^- \]

3. **Counting Sodium Ions**:
- The sodium ions (Na⁺) are located in the octahedral holes of the FCC structure. In the case of NaCl, there are 4 Na⁺ ions per unit cell.
- This is because in an FCC unit cell, there are 4 octahedral voids, and each void can accommodate one Na⁺ ion.

4. **Conclusion**:
- Therefore, each unit cell of NaCl consists of 4 chloride ions (Cl⁻) and 4 sodium ions (Na⁺).
- The final answer is that each unit cell of NaCl consists of 4 chloride ions and 4 sodium ions.

### Final Answer:
Each unit cell of NaCl consists of 4 chloride ions and 4 sodium ions.

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