Which of the following valence electron experiences maximum effective nuclear charge?

Options

A. `4s^(1)`
B. `4p^(1)`
C. `3d^(1)`
D. `2p^(3)`

Answer

To determine which of the following valence electrons experiences the maximum effective nuclear charge, we need to analyze the options provided based on the concepts of nuclear charge and shielding effect.

### Step-by-Step Solution:

1. **Understand Effective Nuclear Charge (Z_eff)**:
- The effective nuclear charge (Z_eff) is defined as the net positive charge experienced by an electron in a multi-electron atom. It can be calculated using the formula:
\[ Z_{\text{eff}} = Z - S \]
where \( Z \) is the total number of protons (nuclear charge) and \( S \) is the shielding constant, which accounts for the repulsion from other electrons.

2. **Identify the Given Options**:
- Option 1: 4s¹
- Option 2: 4p¹
- Option 3: 3d¹
- Option 4: 2p³

3. **Analyze Each Option**:
- **4s¹**: This electron is in the fourth shell and experiences some shielding from the inner electrons.
- **4p¹**: Similar to 4s¹, this electron is also in the fourth shell and experiences shielding from the inner electrons.
- **3d¹**: This electron is in the third shell but is shielded by both the 3s and 3p electrons, which are in the same shell.
- **2p³**: This electron is in the second shell and is shielded less compared to the others since it has fewer inner electrons.

4. **Consider the Shielding Effect**:
- The effective nuclear charge is higher for electrons that are closer to the nucleus and experience less shielding. The 2p³ electron is in the second shell, meaning it is closer to the nucleus compared to the 4s, 4p, and 3d electrons.

5. **Conclusion**:
- The 2p³ electron experiences the least shielding and is closest to the nucleus, leading to the conclusion that it experiences the maximum effective nuclear charge.

### Final Answer:
The valence electron that experiences the maximum effective nuclear charge is **Option D: 2p³**.

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