Copper metal has a face-centred cubic structure with unit cell length equal to 0.361 nm. Picturing copper ions in contact along the face diagonal, find the apparent radius of a copper ion.

Explanation

To find the apparent radius of a copper ion in a face-centered cubic (FCC) structure, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Structure**: In a face-centered cubic (FCC) structure, the atoms are located at each corner of the cube and at the center of each face. The atoms touch along the face diagonal.

2. **Identify the Unit Cell Length**: The unit cell length (A) of copper is given as 0.361 nm.

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