How many chloride ions are there around sodium ion in sodium chloride crystal? (a) 4 (b) 8 (c) 6 (d) 12

Options

A. 4
B. 8
C. 6
D. 12

Answer

To determine how many chloride ions are around a sodium ion in a sodium chloride (NaCl) crystal, we can analyze the crystal structure of sodium chloride.

### Step-by-Step Solution:

1. **Understand the Structure of NaCl**: Sodium chloride crystallizes in a face-centered cubic (FCC) structure. In this arrangement, sodium ions (Na⁺) and chloride ions (Cl⁻) alternate in a three-dimensional lattice.

2. **Identify the Coordination Number**: The coordination number refers to the number of nearest neighbor ions surrounding a particular ion. For sodium ions in NaCl, we need to find how many chloride ions are directly adjacent to it.

3. **Visualize the Arrangement**: In the FCC structure of NaCl:
- Each sodium ion is at the corners and faces of the cube.
- Each chloride ion occupies the octahedral sites.

4. **Count the Nearest Neighbors**: For a sodium ion:
- It is surrounded by six chloride ions. You can visualize this by imagining a sodium ion at the center of an octahedron formed by the chloride ions at the vertices.

5. **Conclusion**: Therefore, the number of chloride ions surrounding a sodium ion in a sodium chloride crystal is 6.

### Final Answer:
(c) 6

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