Coordination number for `Cu` is

Options

A. 1
B. 6
C. 8
D. 12

Answer

To determine the coordination number of copper (Cu), we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Concept of Coordination Number**:
The coordination number is defined as the number of nearest neighboring atoms or ions surrounding a central atom in a crystal structure.

2. **Identify the Crystal Structure of Copper**:
Copper typically crystallizes in a face-centered cubic (FCC) lattice, which is also known as cubic close packing (CCP).

3. **Determine the Coordination Number for FCC/CCP**:
In a face-centered cubic lattice, each atom is surrounded by 12 other atoms. This is because:
- Each corner atom is shared among 8 unit cells (contributing 1/8 to the cell).
- Each face-centered atom is shared between 2 unit cells (contributing 1/2 to the cell).
- Therefore, in total, each atom in an FCC lattice has 12 nearest neighbors.

4. **Conclude the Coordination Number for Copper**:
Since copper adopts the FCC structure, we conclude that the coordination number of copper is 12.

### Final Answer:
The coordination number of copper (Cu) is 12.

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