Question

The element having the highest first ionization enthalpy is

• A. Si
• B. Al
• C. N
• D. C

Answer 1

The Correct Option is C

The objective is to identify the element with the highest first ionization enthalpy from the provided options. Ionization enthalpy is defined as the energy required to detach an electron from a gaseous atom or ion.

Explanation:

• The elements presented are Silicon (Si), Aluminium (Al), Nitrogen (N), and Carbon (C).
• Across a period, ionization enthalpy generally increases due to heightened nuclear charge, which strengthens electron retention.
• Down a group, ionization enthalpy diminishes as atomic radius expands, increasing the distance of valence electrons from the nucleus and enhancing shielding, thereby reducing effective nuclear charge and facilitating electron removal.

Analysis of each element:

1. Silicon (Si): Positioned below Carbon in the same group, Si exhibits a lower ionization enthalpy than C due to its greater distance from the nucleus.
2. Aluminium (Al): Located in Group 13, after Nitrogen and Carbon, Al's first ionization enthalpy is lower than that of N and C because of its elemental position.
3. Nitrogen (N): In Group 15, Nitrogen possesses a higher nuclear charge than Carbon, allowing for a firmer hold on its electrons compared to Al or Si. Its ionization enthalpy is notably high owing to its compact atomic size and the stability of its half-filled p orbital.
4. Carbon (C): Preceding Nitrogen in the periodic table, Carbon has fewer protons, resulting in a lower ionization enthalpy than Nitrogen.

Based on this analysis, Nitrogen (N) demonstrates the highest first ionization enthalpy among the given elements, attributable to its periodic position, small atomic radius, and stable half-filled electron configuration.

Conclusion: The correct answer is \(N\).