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

Options

A. `Zn^(2+)`
B. `Fe^(2+)`
C. `Ni^(1+)`
D. `Cu^(+)`

Explanation

To determine which of the given ions has the maximum number of unpaired d-electrons, we need to analyze the electronic configurations of each ion. Here’s a step-by-step solution:

### Step 1: Identify the ions and their electronic configurations
We need to look at the ions provided in the question. Let's assume they are:
1. Zn²⁺
2. Fe²⁺
3. Ni⁺
4. Cu⁺

### Step 2: Determine the electronic configuration of each ion
1. **Zn²⁺ (Zinc)**
- Atomic number of Zn = 30
- Ground state electronic configuration: [Ar] 4s² 3d¹⁰
- For Zn²⁺, we remove 2 electrons from 4s:
- Configuration: [Ar] 3d¹⁰
- Unpaired d-electrons: **0**

2. **Fe²⁺ (Iron)**
- Atomic number of Fe = 26
- Ground state electronic configuration: [Ar] 4s² 3d⁶
- For Fe²⁺, we remove 2 electrons from 4s:
- Configuration: [Ar] 3d⁶
- Filling the d-orbitals:
- 1, 2, 3, 4, 5 (5 electrons in separate orbitals) and then 6 (paired in one orbital).
- Unpaired d-electrons: **4**

3. **Ni⁺ (Nickel)**
- Atomic number of Ni = 28
- Ground state electronic configuration: [Ar] 4s² 3d⁸
- For Ni⁺, we remove 1 electron from 4s:
- Configuration: [Ar] 4s¹ 3d⁸
- Filling the d-orbitals:
- 1, 2, 3, 4, 5, 6, 7, 8 (8 electrons).
- Unpaired d-electrons: **2**

4. **Cu⁺ (Copper)**
- Atomic number of Cu = 29
- Ground state electronic configuration: [Ar] 4s² 3d¹⁰
- For Cu⁺, we remove 1 electron from 4s:
- Configuration: [Ar] 3d¹⁰
- Unpaired d-electrons: **0**

### Step 3: Compare the number of unpaired d-electrons
- Zn²⁺: 0 unpaired d-electrons
- Fe²⁺: 4 unpaired d-electrons
- Ni⁺: 2 unpaired d-electrons
- Cu⁺: 0 unpaired d-electrons

### Conclusion
The ion with the maximum number of unpaired d-electrons is **Fe²⁺**, which has **4 unpaired d-electrons**. Therefore, the correct answer is option number 2 (Fe²⁺).

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