Which element has the highest first ionization potential ?

Options

A. N
B. Ne
C. He
D. H

Explanation

To determine which element has the highest first ionization potential, we will analyze the ionization potentials of the given elements: nitrogen, neon, helium, and hydrogen.

### Step-by-Step Solution:

1. **Understanding Ionization Potential**:
- Ionization potential (or ionization energy) is the amount of energy required to remove the outermost electron from an isolated gaseous atom.

2. **Writing Electron Configurations**:
- For each element, we will write the electron configuration:
- **Hydrogen (H)**: 1s¹
- **Helium (He)**: 1s²
- **Nitrogen (N)**: 1s² 2s² 2p³
- **Neon (Ne)**: 1s² 2s² 2p⁶

3. **Identifying Stability of Electron Configurations**:
- Atoms with completely filled or half-filled orbitals are more stable.
- Helium has a completely filled 1s² configuration, while neon has a completely filled 2s² 2p⁶ configuration.
- Nitrogen has a half-filled 2p³ configuration, and hydrogen has a single electron in 1s.

4. **Comparing Ionization Energies**:
- Generally, the more stable the electron configuration, the higher the ionization energy.
- Neon and helium are noble gases, which typically have high ionization energies due to their stable electron configurations.
- However, helium has its electrons closer to the nucleus compared to neon, leading to a stronger attraction between the nucleus and the outermost electron.

5. **Conclusion**:
- Among the given elements, helium (He) has the highest first ionization potential due to its completely filled 1s² configuration and the proximity of its electrons to the nucleus.

### Final Answer:
**Helium (He) has the highest first ionization potential.**

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