Nitrogen atom has 3 unpaired electrons in its ground state. It can be explained by

Options

A. Auf - bau principle
B. Paulis principle
C. Hund's rule
D. None of these

Answer

To explain why a nitrogen atom has three unpaired electrons in its ground state, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Atomic Number of Nitrogen:**
- The atomic number of nitrogen (N) is 7. This means it has 7 electrons.

2. **Determine the Electronic Configuration:**
- The electronic configuration of nitrogen can be written as:
- 1s² 2s² 2p³
- Here, the 1s and 2s orbitals are fully filled with 2 electrons each, and the 2p orbital has 3 electrons.

3. **Understand the Distribution of Electrons in Orbitals:**
- According to the Aufbau principle, electrons fill orbitals starting from the lowest energy level to the highest.
- The 1s and 2s orbitals are filled first, followed by the 2p orbitals.

4. **Apply Hund's Rule:**
- Hund's Rule states that for degenerate orbitals (orbitals of the same energy, such as the three 2p orbitals), electrons will occupy each orbital singly before pairing up.
- In the case of nitrogen, the three electrons in the 2p orbital will occupy the three available 2p orbitals singly:
- 2p_x¹ 2p_y¹ 2p_z¹
- This results in three unpaired electrons.

5. **Conclusion:**
- Therefore, the presence of three unpaired electrons in the ground state of nitrogen can be explained by Hund's Rule, which dictates that electrons will first fill degenerate orbitals singly before pairing.

### Final Answer:
The nitrogen atom has three unpaired electrons in its ground state, which can be explained by Hund's Rule.

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