The element having the highest first ionization enthalpy is

We need to determine which element among Si, Al, N, and C has the highest first ionization enthalpy.

The first ionization enthalpies (approximate values) are:

Al (Z = 13): 577 kJ/mol

Si (Z = 14): 786 kJ/mol

C (Z = 6): 1086 kJ/mol

N (Z = 7): 1402 kJ/mol

General trend: Ionization enthalpy increases across a period from left to right. However, there are exceptions due to electronic configuration stability.

Why Nitrogen has the highest IE among these elements:

Nitrogen has the electronic configuration $$1s^2\, 2s^2\, 2p^3$$. The $$2p$$ subshell is exactly half-filled, with one electron in each of the three $$2p$$ orbitals. This half-filled configuration provides extra stability due to:

1. Maximum exchange energy

2. Symmetrical distribution of electrons

This extra stability makes it significantly harder to remove an electron from nitrogen compared to the other elements listed.

The correct answer is Option 3: N (Nitrogen).