Which of the following is electronic configuration of `Cu^(2+)` (Z=29)?

Options

A. `[Ar]4s^(1)3d^(8)`
B. `[Ar]4s^(2) 3d^(10)4p^(1)`
C. `[Ar]4s^(-1)3d^(10)`
D. `[Ar]3d^(9)`

Explanation

To determine the electronic configuration of the copper ion \( \text{Cu}^{2+} \) (with atomic number \( Z = 29 \)), we can follow these steps:

### Step 1: Determine the electronic configuration of neutral copper (Cu).
- The atomic number \( Z = 29 \) indicates that a neutral copper atom has 29 electrons.
- The electronic configuration of a neutral copper atom is filled according to the Aufbau principle, which leads to:
\[ \text{Cu: } 1s^2 \, 2s^2 \, 2p^6 \, 3s^2 \, 3p^6 \, 4s^1 \, 3d^{10} \]
- Here, we can see that the 4s subshell is filled before the 3d subshell, but copper has a unique configuration where one electron from the 4s subshell is used to stabilize the fully filled 3d subshell.

### Step 2: Determine the number of electrons in \( \text{Cu}^{2+} \).
- To find the electronic configuration of \( \text{Cu}^{2+} \), we need to remove 2 electrons from the neutral copper atom.
- Electrons are removed first from the outermost shell (4s) and then from the next outer shell (3d).

### Step 3: Remove electrons to find the configuration of \( \text{Cu}^{2+} \).
- Starting from the neutral copper configuration:
\[ 1s^2 \, 2s^2 \, 2p^6 \, 3s^2 \, 3p^6 \, 4s^1 \, 3d^{10} \]
- Remove 1 electron from the 4s subshell and 1 electron from the 3d subshell:
- Remove \( 4s^1 \) → \( 4s^0 \)
- Remove \( 3d^{10} \) → \( 3d^9 \)

Thus, the electronic configuration for \( \text{Cu}^{2+} \) becomes:
\[ \text{Cu}^{2+}: 1s^2 \, 2s^2 \, 2p^6 \, 3s^2 \, 3p^6 \, 3d^9 \]

### Step 4: Write the configuration using the noble gas notation.
- The noble gas preceding copper is argon (Ar), which has the configuration \( 1s^2 \, 2s^2 \, 2p^6 \, 3s^2 \, 3p^6 \) or simply [Ar].
- Therefore, the electronic configuration of \( \text{Cu}^{2+} \) can be expressed as:
\[ \text{Cu}^{2+}: [\text{Ar}] \, 3d^9 \]

### Conclusion:
The electronic configuration of \( \text{Cu}^{2+} \) is:
\[ [\text{Ar}] \, 3d^9 \]