Which of the following has maximum of unpaired d- electrons ?

Options

A. `N^(3+)`
B. `Fe^(2+)`
C. `Zn^(+)`
D. `Cu^+`

Answer

To determine which of the given ions has the maximum number of unpaired d-electrons, we will analyze the electronic configurations of each ion step by step.

### Step 1: Analyze the ions
The ions we need to analyze are:
1. N³⁺
2. Fe²⁺
3. Zn⁺
4. Cu⁺

### Step 2: Determine the electronic configuration of N³⁺
- The atomic number of nitrogen (N) is 7. Its ground state electronic configuration is:
- 1s² 2s² 2p³
- For N³⁺, we remove 3 electrons:
- N³⁺: 1s² 2s² 2p⁰
- The d-subshell is not filled, so there are **0 unpaired d-electrons**.

### Step 3: Determine the electronic configuration of Fe²⁺
- The atomic number of iron (Fe) is 26. Its ground state electronic configuration is:
- 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d⁶
- For Fe²⁺, we remove 2 electrons (from the 4s subshell):
- Fe²⁺: 1s² 2s² 2p⁶ 3s² 3p⁶ 3d⁶
- The d-subshell (3d) has 6 electrons. According to Hund's rule, we fill the orbitals singly before pairing. Thus, the distribution in the 3d subshell is:
- ↑ ↑ ↑ ↑ ↓ ↓ (4 unpaired electrons)
- So, Fe²⁺ has **4 unpaired d-electrons**.

### Step 4: Determine the electronic configuration of Zn⁺
- The atomic number of zinc (Zn) is 30. Its ground state electronic configuration is:
- 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰
- For Zn⁺, we remove 1 electron (from the 4s subshell):
- Zn⁺: 1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s⁰
- The d-subshell (3d) has 10 electrons, which means all orbitals are fully filled:
- ↑↓ ↑↓ ↑↓ ↑↓ ↑↓ (0 unpaired electrons)
- So, Zn⁺ has **0 unpaired d-electrons**.

### Step 5: Determine the electronic configuration of Cu⁺
- The atomic number of copper (Cu) is 29. Its ground state electronic configuration is:
- 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰
- For Cu⁺, we remove 1 electron (from the 4s subshell):
- Cu⁺: 1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s⁰
- The d-subshell (3d) also has 10 electrons, which means all orbitals are fully filled:
- ↑↓ ↑↓ ↑↓ ↑↓ ↑↓ (0 unpaired electrons)
- So, Cu⁺ has **0 unpaired d-electrons**.

### Conclusion
After analyzing all the ions:
- N³⁺: 0 unpaired d-electrons
- Fe²⁺: 4 unpaired d-electrons (maximum)
- Zn⁺: 0 unpaired d-electrons
- Cu⁺: 0 unpaired d-electrons

The ion with the maximum number of unpaired d-electrons is **Fe²⁺ with 4 unpaired d-electrons**.