Number of unpaired electrons in `Fe^(3+)` (Z = 26) is

Options

A. 0
B. 2
C. 3
D. 5

Explanation

To determine the number of unpaired electrons in the `Fe^(3+)` ion, we will follow these steps:

### Step 1: Identify the Atomic Number
The atomic number of iron (Fe) is 26. This means that a neutral iron atom has 26 electrons.

### Step 2: Write the Electron Configuration of Neutral Iron (Fe)
The electron configuration for a neutral iron atom (Fe) is:
- 1s² 2s² 2p⁶ 3s² 3p⁶ 3d⁶ 4s²

This configuration accounts for all 26 electrons.

### Step 3: Determine the Electron Configuration of `Fe^(3+)`
When iron loses three electrons to form `Fe^(3+)`, it loses the electrons from the outermost shell first. The 4s orbital is filled before the 3d orbital, so the electrons are removed in the following order:
- 2 electrons from the 4s orbital
- 1 electron from the 3d orbital

Thus, the electron configuration of `Fe^(3+)` becomes:
- 1s² 2s² 2p⁶ 3s² 3p⁶ 3d⁵ 4s⁰

### Step 4: Analyze the 3d Subshell
Now, we focus on the 3d subshell, which has 5 electrons (3d⁵). According to Hund's rule, electrons will fill degenerate orbitals singly before pairing up. Therefore, the distribution of the 5 electrons in the 3d orbitals will be as follows:
- Each of the 5 d orbitals will have 1 electron.

### Step 5: Count the Unpaired Electrons
Since all 5 electrons in the 3d subshell are unpaired (each occupying separate orbitals), the number of unpaired electrons in `Fe^(3+)` is:
- **5 unpaired electrons.**

### Final Answer
The number of unpaired electrons in `Fe^(3+)` is **5**.

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