The coordination number of an atom in a body- centered cubic structure is
[Assume that the lattice is made up of atoms.)

Answer

To determine the coordination number of an atom in a body-centered cubic (BCC) structure, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding the BCC Structure**:
- In a body-centered cubic (BCC) unit cell, there is one atom located at the center of the cube and additional atoms located at each of the eight corners of the cube.

2. **Identifying the Atoms**:
- The central atom is surrounded by the corner atoms. Each corner of the cube is occupied by an atom.

3. **Defining Coordination Number**:
- The coordination number is defined as the number of nearest neighboring atoms that surround a given atom. In this case, we are interested in the coordination number of the atom located at the center of the BCC unit cell.

4. **Counting the Nearest Neighbors**:
- The central atom in the BCC structure is in contact with the corner atoms. Each corner atom is a nearest neighbor to the central atom.
- In the BCC structure, the central atom touches 8 corner atoms.

5. **Conclusion**:
- Therefore, the coordination number of the atom in a body-centered cubic structure is 8.

### Final Answer:
The coordination number of an atom in a body-centered cubic structure is **8**.

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