The coordination number of sodium in sodium oxide is:

Options

A. 6
B. 8
C. 4
D. 2

Answer

To determine the coordination number of sodium in sodium oxide (Na2O), we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Chemical Formula**:
The chemical formula for sodium oxide is Na2O. This indicates that there are two sodium ions (Na⁺) for every oxide ion (O²⁻).

2. **Understand the Crystal Structure**:
Sodium oxide crystallizes in an anti-fluoride type of structure, which is characterized by a face-centered cubic (FCC) lattice arrangement.

3. **Visualize the Lattice**:
In the anti-fluoride structure, the oxide ions (O²⁻) are located at the face-centered positions of the cubic lattice, while the sodium ions (Na⁺) occupy the tetrahedral voids.

4. **Determine Coordination Number**:
The coordination number is defined as the number of atoms or ions that surround a central atom or ion. In the case of sodium ions in sodium oxide, each sodium ion is surrounded by four oxide ions.

5. **Conclusion**:
Therefore, the coordination number of sodium in sodium oxide is 4.

### Final Answer:
The coordination number of sodium in sodium oxide is **4**.

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