Both Cu and Zn have completely filled 3d atomic orbitals. Cu is considered as transition elements but Zn is not. Explain.

Explanation

To explain why copper (Cu) is considered a transition element while zinc (Zn) is not, despite both having completely filled 3d atomic orbitals, we need to analyze their electronic configurations and the nature of their cations.

### Step-by-Step Solution:

1. **Electronic Configuration of Copper (Cu)**:
- The atomic number of copper is 29. Its electronic configuration is:
\[
\text{Cu: } [\text{Ar}] 4s^1 3d^{10}
...