The number of `d` electrons in `Fe^(2+)` (atomic number of `Fe = 26`) is equal to

Explanation

To determine the number of `d` electrons in `Fe^(2+)`, we will follow these steps:

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

### Step 2: Write the electronic configuration of neutral Iron (Fe)
The electronic configuration of a neutral iron atom can be written as follows:
- 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d⁶

This can be broken down as:
- 1s: 2 electrons
- 2s: 2 electrons
- 2p: 6 electrons
- 3s: 2 electrons
- 3p: 6 electrons
- 4s: 2 electrons
- 3d: 6 electrons

### Step 3: Determine the electronic configuration of `Fe^(2+)`
For the `Fe^(2+)` ion, we need to remove two electrons from the neutral iron atom. The electrons are removed from the outermost shell first, which in this case are the 4s electrons.

Thus, the electronic configuration of `Fe^(2+)` becomes:
- 1s² 2s² 2p⁶ 3s² 3p⁶ 3d⁶

### Step 4: Count the number of `d` electrons
In the electronic configuration of `Fe^(2+)`, we see that there are 6 electrons in the 3d subshell. Therefore, the number of `d` electrons in `Fe^(2+)` is 6.

### Final Answer
The number of `d` electrons in `Fe^(2+)` is **6**.

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