Which of the following have least electron affinity?

Options

A. Nitrogen
B. Oxygen
C. Fluorine
D. Carbon

Explanation

To determine which of the given elements has the least electron affinity, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Elements**: We need to analyze the electron affinity of the following elements: Carbon (C), Nitrogen (N), Oxygen (O), and Fluorine (F).

2. **Understand Electron Affinity**: Electron affinity is the amount of energy released when an electron is added to a neutral atom in the gaseous state. Generally, electron affinity increases across a period from left to right due to increasing nuclear charge.

3. **Arrange the Elements by Period**: All the given elements belong to the second period of the periodic table:
- Carbon (C) - 2s² 2p²
- Nitrogen (N) - 2s² 2p³
- Oxygen (O) - 2s² 2p⁴
- Fluorine (F) - 2s² 2p⁵

4. **Analyze Trends in Electron Affinity**:
- As we move from Carbon to Fluorine, the electron affinity generally increases.
- However, Nitrogen has a unique electronic configuration (2s² 2p³) which is half-filled, providing extra stability. This stability means that adding an electron to Nitrogen requires more energy compared to Carbon, Oxygen, and Fluorine.

5. **Conclusion**: Given that Nitrogen has a half-filled p subshell, it is less favorable for it to gain an additional electron compared to the other elements. Therefore, Nitrogen has the least electron affinity among the four elements.

### Final Answer:
**Nitrogen (N) has the least electron affinity.**

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