Which electronic configuration will show the highest first ionization enthalpy ?

Options

A. `1s ^(2) 2s ^(2) 2p ^(1)`
B. `1s ^(2) 2s ^(2) 2p ^(5)`
C. `1s ^(2) 2s ^(2) 2p ^(3)`
D. `1s ^(2) 2s ^(2)`

Answer

To determine which electronic configuration shows the highest first ionization enthalpy, we need to analyze the given configurations and understand the factors that influence ionization enthalpy.

### Step-by-Step Solution:

1. **Understanding Ionization Enthalpy**:
- Ionization enthalpy is the amount of energy required to remove the outermost electron from an isolated gaseous atom. Higher ionization enthalpy indicates a stronger hold on the outermost electron.

2. **Given Electronic Configurations**:
- 1s² 2s² 2p¹ (Boron)
- 1s² 2s² 2p⁵ (Fluorine)
- 1s² 2s² 2p³ (Nitrogen)
- 1s² 2s² (Beryllium)

3. **Trends in Ionization Enthalpy**:
- Ionization enthalpy generally increases across a period from left to right due to increasing nuclear charge, which increases the attraction between the nucleus and the electrons.
- Smaller atomic size leads to higher ionization enthalpy because the outermost electrons are held more tightly by the nucleus.

4. **Analyzing Each Configuration**:
- **Beryllium (1s² 2s²)**: Has a full 2s subshell, relatively low ionization enthalpy.
- **Boron (1s² 2s² 2p¹)**: Has three valence electrons, higher than beryllium but still relatively low.
- **Nitrogen (1s² 2s² 2p³)**: Has a half-filled p subshell, which is stable, but its atomic size is larger than fluorine.
- **Fluorine (1s² 2s² 2p⁵)**: Has a nearly full p subshell and the smallest atomic size among the given configurations, leading to the highest ionization enthalpy.

5. **Conclusion**:
- Among the given configurations, **Fluorine (1s² 2s² 2p⁵)** will show the highest first ionization enthalpy due to its small atomic size and high nuclear charge, which results in a strong attraction to its outermost electron.

### Final Answer:
The electronic configuration that shows the highest first ionization enthalpy is **1s² 2s² 2p⁵ (Fluorine)**.

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