The electronic configuration of an element with atomic number 24 is

Options

A. `1s^2,2s^2,2p^6,3s^2,3p^6,3d^4,4s^2`
B. `1s^2,2s^2,2p^6,3s^2,3p^6,3d^10`
C. `1s^2,2s^2,2p^6,3s^2,3p^6,3d^6`
D. `1s^2,2s^2,2p^6,3s^2,3p^6,3d^5,4s^1`

Answer

To determine the electronic configuration of the element with atomic number 24, which is Chromium (Cr), we will follow these steps:

### Step-by-Step Solution:

1. **Identify the Atomic Number**: The atomic number of the element is given as 24. This means that the element has 24 electrons.

2. **Write the Basic Electron Configuration**:
- Start filling the orbitals according to the Aufbau principle, which states that electrons occupy the lowest energy orbitals first.
- The order of filling is:
- 1s, 2s, 2p, 3s, 3p, 4s, 3d.

3. **Fill the Orbitals**:
- 1s can hold 2 electrons: **1s²**
- 2s can hold 2 electrons: **2s²**
- 2p can hold 6 electrons: **2p⁶**
- 3s can hold 2 electrons: **3s²**
- 3p can hold 6 electrons: **3p⁶**
- Up to this point, we have filled 2 + 2 + 6 + 2 + 6 = 18 electrons.

4. **Continue Filling**:
- Next, we fill the 4s orbital, which can hold 2 electrons: **4s²**.
- Now we have filled 18 + 2 = 20 electrons.

5. **Fill the 3d Orbital**:
- Now, we have 4 electrons left to place, which will go into the 3d orbital. However, Chromium is an exception to the typical filling order.
- Instead of filling the 3d orbital with 4 electrons (which would be **3d⁴**), one electron from the 4s orbital is moved to the 3d orbital to achieve a more stable half-filled configuration.
- Therefore, we have **3d⁵** instead of **3d⁴**.

6. **Final Electronic Configuration**:
- Putting it all together, the electronic configuration of Chromium (Cr) with atomic number 24 is:
- **1s² 2s² 2p⁶ 3s² 3p⁶ 4s¹ 3d⁵**.

### Final Answer:
The electronic configuration of the element with atomic number 24 (Chromium) is **1s² 2s² 2p⁶ 3s² 3p⁶ 4s¹ 3d⁵**.

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