Which electronic configuration of an element has abnormally high difference between second and third ionization energy?

Options

A. `1s^(2)2s^(2)2p^(6)3s^(1)`
B. `1s^(2)2s^(2)2p^(6)3s^(2)3p^(1)`
C. `1s^(2)2s^(2)2p^(6)`
D. `1s^(2)2s^(2)2p^(6)3s^(2)`.

Answer

To determine which electronic configuration of an element has an abnormally high difference between the second and third ionization energy, we need to analyze the given configurations step by step.

### Step-by-Step Solution:

1. **Understanding Ionization Energy**:
- Ionization energy is the energy required to remove an electron from an atom. The first ionization energy (IE1) is the energy needed to remove the first electron, the second ionization energy (IE2) is for the second electron, and so on.
- The significant difference between the second and third ionization energy (IE2 and IE3) usually occurs when the electron being removed is from a different shell or subshell than the previous one.

2. **Analyzing Each Configuration**:
- **Option 1: 1s² 2s² 2p⁶ 3s¹**
- IE1: Remove 3s¹ → relatively low energy.
- IE2: Remove 2p⁶ → higher energy (removing from a filled subshell).
- IE3: Remove 2s² → still higher energy.
- **Difference (IE2 - IE3)**: Not abnormally high.

- **Option 2: 1s² 2s² 2p⁶ 3s² 3p¹**
- IE1: Remove 3p¹ → low energy.
- IE2: Remove 3s² → higher energy.
- IE3: Remove 2p⁶ → much higher energy.
- **Difference (IE2 - IE3)**: Not abnormally high.

- **Option 3: 1s² 2s² 2p⁶ 3s² 3p²**
- IE1: Remove 3p² → low energy.
- IE2: Remove 3p¹ → still low energy.
- IE3: Remove 3s² → higher energy.
- **Difference (IE2 - IE3)**: Not abnormally high.

- **Option 4: 1s² 2s² 2p⁶ 3s² 3p³**
- IE1: Remove 3p³ → low energy.
- IE2: Remove 3p² → still low energy.
- IE3: Remove 3s² → higher energy.
- **Difference (IE2 - IE3)**: Not abnormally high.

3. **Identifying the Configuration with High Difference**:
- The key is to find a configuration where the second ionization energy is significantly lower than the third. This typically occurs when the second electron is removed from a higher energy level (like 3s or 3p) and the third electron is removed from a lower energy level (like 2s or 2p).
- The configuration that fits this description is **1s² 2s² 2p⁶ 3s² 3p¹**, where the second ionization energy is from the 3p subshell and the third ionization energy is from the 2p subshell.

### Conclusion:
The electronic configuration with an abnormally high difference between the second and third ionization energy is **1s² 2s² 2p⁶ 3s² 3p¹**.