The number of unpaired electrons in `Fe^(3+)` ion are

Options

A. 1
B. 0
C. 4
D. 5

Answer

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

### Step 1: Determine the Atomic Number of Iron
Iron (Fe) has an atomic number of 26. This means it has 26 electrons in its neutral state.

### Step 2: Write the Electronic Configuration of Neutral Iron
The electronic configuration of neutral iron can be written as:
\[ \text{Fe: } 1s^2 \, 2s^2 \, 2p^6 \, 3s^2 \, 3p^6 \, 3d^6 \, 4s^2 \]

### Step 3: Determine the Electronic Configuration of `Fe^(3+)`
To find the electronic configuration of the `Fe^(3+)` ion, we need to remove 3 electrons from the neutral iron configuration. Electrons are removed first from the outermost shell (4s) and then from the 3d subshell.

1. Remove 2 electrons from the 4s subshell: \(4s^2 \rightarrow 4s^0\)
2. Remove 1 electron from the 3d subshell: \(3d^6 \rightarrow 3d^5\)

Thus, the electronic configuration of `Fe^(3+)` is:
\[ \text{Fe}^{3+}: 1s^2 \, 2s^2 \, 2p^6 \, 3s^2 \, 3p^6 \, 3d^5 \]

### Step 4: Analyze the 3d Subshell for Unpaired Electrons
Now, we focus on the 3d subshell, which has 5 electrons. The distribution of these electrons in the 3d orbitals follows Hund's rule, which states that electrons will fill degenerate orbitals singly before pairing up.

The 3d subshell can be represented as:
- \(3d: \uparrow \, \uparrow \, \uparrow \, \uparrow \, \uparrow\)

This shows that all 5 electrons in the 3d subshell are unpaired.

### Step 5: Conclusion
Therefore, the number of unpaired electrons in the `Fe^(3+)` ion is **5**.

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

---