Electronic configurations of `Cu ( Z = 29)` is

Options

A. `[Ar] 3d^(9) 4 s^(2)`
B. `[Ar] 3d^(5) 4 s^(2)`
C. `[Ar] 3d^(10) 4 s^(1)`
D. `[Ar] 3d^(6) 4 s^(2)`

Explanation

To determine the electronic configuration of copper (Cu), which has an atomic number of 29, we can follow these steps:

### Step 1: Determine the total number of electrons
Since the atomic number (Z) of copper is 29, it has 29 electrons.

### Step 2: Fill the electron orbitals according to the Aufbau principle
We fill the orbitals in the order of increasing energy levels, following the Aufbau principle, Hund's rule, and the Pauli exclusion principle. The order of filling is as follows:

1. 1s
2. 2s
3. 2p
4. 3s
5. 3p
6. 4s
7. 3d
8. 4p
9. 5s
10. 4d
11. 5p
12. 6s
13. 4f
14. 5d
15. 6p

### Step 3: Fill the orbitals up to 29 electrons
1. **1s²** = 2 electrons
2. **2s²** = 2 electrons
3. **2p⁶** = 6 electrons
4. **3s²** = 2 electrons
5. **3p⁶** = 6 electrons
6. **4s²** = 2 electrons
7. **3d¹⁰** = 10 electrons (filling the 3d subshell)
8. **4s¹** = 1 electron (the last electron goes into the 4s subshell)

### Step 4: Write the electronic configuration
The electronic configuration of copper can be written as:
\[ \text{Cu: } [\text{Ar}] \, 3d^{10} \, 4s^1 \]

### Step 5: Explain the stability of the configuration
Copper has a unique electronic configuration where the 3d subshell is fully filled (10 electrons) and the 4s subshell is half filled (1 electron). This configuration is more stable than the expected configuration of \( [\text{Ar}] \, 3d^9 \, 4s^2 \) due to the stability associated with fully filled and half-filled subshells.

### Final Answer
The electronic configuration of copper (Cu) is:
\[ \text{Cu: } [\text{Ar}] \, 3d^{10} \, 4s^1 \]

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