Arrange N, O and S in order of decreasing electron affinity:

Options

A. SgtOgtN
B. OgtSgtN
C. NgtOgtS
D. SgtNgtO

Answer

To arrange nitrogen (N), oxygen (O), and sulfur (S) in order of decreasing electron affinity, we will follow these steps:

### Step 1: Understand Electron Affinity
Electron affinity is the energy change that occurs when an electron is added to a neutral atom in the gas phase. A higher electron affinity value indicates a greater tendency to attract an electron.

### Step 2: Consider the Periodic Trends
- **Across a Period**: As we move from left to right across a period, the electron affinity generally increases due to increasing nuclear charge (Z effective) and decreasing atomic size.
- **Down a Group**: As we move down a group, the electron affinity generally decreases due to increasing atomic size and increased electron shielding.

### Step 3: Analyze the Elements
- **Nitrogen (N)**: Located in the second period, it has a relatively high electron affinity, but it is less than that of oxygen due to its larger atomic size and lower Z effective.
- **Oxygen (O)**: Also in the second period, oxygen has a higher electron affinity than nitrogen because it is more effective at attracting an additional electron due to its smaller size and higher nuclear charge.
- **Sulfur (S)**: Located in the third period, sulfur has a lower electron affinity than both nitrogen and oxygen. Although it has a higher atomic number, its larger atomic size and increased shielding reduce its ability to attract an additional electron.

### Step 4: Compare the Electron Affinities
Based on the analysis:
1. Oxygen (O) has the highest electron affinity.
2. Nitrogen (N) comes next.
3. Sulfur (S) has the lowest electron affinity.

### Final Order
Thus, the order of decreasing electron affinity is:
**O > N > S**

### Summary
The final arrangement of nitrogen, oxygen, and sulfur in order of decreasing electron affinity is:
**Oxygen (O) > Nitrogen (N) > Sulfur (S)**