The electronic configuration of iron (26) is

Options

A. 2,8,14
B. 2,8,12,2
C. 2,8,10,4
D. 2,8,14,1

Answer

To determine the electronic configuration of iron (atomic number 26), we can follow these steps:

### Step 1: Identify the Atomic Number
The atomic number of iron is 26. This means that an iron atom has 26 electrons.

### Step 2: Fill the Electron Shells
Electrons fill the atomic orbitals in a specific order based on the Aufbau principle, which states that electrons occupy the lowest energy orbitals first. The order of filling is as follows:

1. 1s
2. 2s
3. 2p
4. 3s
5. 3p
6. 4s
7. 3d

### Step 3: Distribute the Electrons
Now, we will distribute the 26 electrons according to the order of filling:

- **1s** can hold 2 electrons: 1s² (2 electrons)
- **2s** can hold 2 electrons: 2s² (2 electrons)
- **2p** can hold 6 electrons: 2p⁶ (6 electrons)
- **3s** can hold 2 electrons: 3s² (2 electrons)
- **3p** can hold 6 electrons: 3p⁶ (6 electrons)
- **4s** can hold 2 electrons: 4s² (2 electrons)
- **3d** can hold 10 electrons, but we only need 6 for iron: 3d⁶ (6 electrons)

### Step 4: Write the Full Electronic Configuration
Combining all the filled orbitals, we get the electronic configuration of iron:

1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d⁶

### Step 5: Write the Shortened Configuration
Using the nearest noble gas (argon, which has an atomic number of 18) to simplify, we can write the electronic configuration as:

[Ar] 4s² 3d⁶

### Step 6: Verify the Total Number of Electrons
To ensure the configuration is correct, we can count the total number of electrons:

- 1s² = 2
- 2s² = 2
- 2p⁶ = 6
- 3s² = 2
- 3p⁶ = 6
- 4s² = 2
- 3d⁶ = 6

Adding these gives us: 2 + 2 + 6 + 2 + 6 + 2 + 6 = 26, which matches the atomic number of iron.

### Final Answer
The electronic configuration of iron (26) is:
**[Ar] 4s² 3d⁶** or in terms of distribution: **2, 8, 14, 2**.