Sodium chloride , NaCl , usually crystallizes in a face - centered cubic lattice. How many ions are in contact with any single `Na^(+)` ion ?

Options

A. 4
B. 6
C. 8
D. 1

Answer

To determine how many ions are in contact with a single Na⁺ ion in sodium chloride (NaCl), which crystallizes in a face-centered cubic (FCC) lattice, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Structure of NaCl**:
- Sodium chloride crystallizes in a face-centered cubic lattice. In this structure, chloride ions (Cl⁻) occupy the face-centered and corner positions of the cube, while sodium ions (Na⁺) occupy the octahedral voids.

2. **Identify the Position of Na⁺ Ions**:
- In the FCC lattice, each unit cell has one Na⁺ ion located at the center of the octahedral voids. The octahedral voids are located at the center of the cube and at the edge centers.

3. **Determine the Nearest Neighbors**:
- Each Na⁺ ion is surrounded by Cl⁻ ions. To find out how many ions are in contact with a single Na⁺ ion, we need to identify the nearest Cl⁻ ions.

4. **Visualize the Contacts**:
- In the FCC lattice, each Na⁺ ion is surrounded by 6 Cl⁻ ions. These ions are located at the corners of the cube and the centers of the faces of the cube.

5. **Count the Contact Ions**:
- Therefore, for any single Na⁺ ion, there are 6 Cl⁻ ions in contact with it.

6. **Conclusion**:
- The total number of ions in contact with a single Na⁺ ion is 6.

### Final Answer:
The number of ions in contact with any single Na⁺ ion in NaCl is **6**.

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