Which is incorrect for EA ?

Options

A. `CIgtFgtBrgtIgtS`
B. `O^(_)gtOgtO^(+)`
C. `S^(-)gtO^(-)`
D. `CIgtFgtSgtOgtNgtP`

Answer

To determine which statement regarding electron affinity (EA) is incorrect, we need to analyze the trends in electron affinity across different groups in the periodic table, specifically focusing on the elements mentioned in the question: Oxygen, Sulfur, Fluorine, Chlorine, Nitrogen, and Phosphorus.

### Step-by-Step Solution:

1. **Understanding Electron Affinity (EA)**:
- Electron affinity is the amount of energy released when an electron is added to a neutral atom in the gas phase. A more negative EA value indicates a greater tendency to gain an electron.

2. **Trends in Electron Affinity**:
- As we move across a period from left to right, the electron affinity generally increases due to increasing nuclear charge.
- As we move down a group, the electron affinity generally decreases due to the increase in atomic size and shielding effect.

3. **Analyzing Group 15 Elements (Nitrogen and Phosphorus)**:
- For nitrogen (N), the electron affinity is less than that of phosphorus (P) due to the increased distance of the outer electrons from the nucleus in phosphorus.

4. **Analyzing Group 16 Elements (Oxygen and Sulfur)**:
- Oxygen (O) has a negative EA value of approximately -141 kJ/mol, indicating it releases energy when gaining an electron.
- However, when considering the addition of a second electron to form O²⁻, the EA becomes positive (+780 kJ/mol), indicating that energy is required to add the second electron due to electron-electron repulsion.
- Sulfur (S), on the other hand, has a more negative EA value for its first electron compared to oxygen, approximately -200 kJ/mol, because it has available d-orbitals that can accommodate additional electrons.

5. **Analyzing Group 17 Elements (Fluorine and Chlorine)**:
- Fluorine (F) has a high electron affinity, but it is less than that of chlorine (Cl) due to the lack of d-orbitals in fluorine, which leads to higher electron-electron repulsion in a small atom like fluorine.

6. **Comparing Electron Affinities**:
- The expected order of electron affinities based on the above analysis is:
- Cl > F (Chlorine has a higher EA than Fluorine)
- S > O (Sulfur has a higher EA than Oxygen)
- P > N (Phosphorus has a higher EA than Nitrogen)

7. **Identifying the Incorrect Statement**:
- Based on the analysis, the incorrect statement is that the EA of O⁺ is less than that of O, which contradicts the understanding that O⁺ would have a higher tendency to gain an electron due to its positive charge and the high nuclear charge.

### Conclusion:
The incorrect statement regarding electron affinity is related to the comparison of O⁺ and O, where O⁺ should have a greater electron affinity than O.