The element having the highest first ionization enthalpy among Si, Al, N and C is:
Classification of Elements & Periodicity · Class 11 · JEE Main Previous Year Question
The element having the highest first ionization enthalpy among Si, Al, N and C is:
- a
Si
- b
Al
- c✓
N
- d
C
N
🧠 Half-filled p-subshell in N gives it extra stability and higher IE Nitrogen () has exactly 3 electrons in 3 separate p-orbitals — no pairing, no repulsion. This half-filled configuration is extra stable, so more energy is needed to remove an electron.
🗺️ Compare the four elements Al (Group 13, Period 3) has the lowest IE among the four. Si (Group 14, Period 3) is next. C (Group 14, Period 2) is higher. N beats C because of the half-filled stability. So N is highest.
⚠️ Common mistake O comes after N in the period, but O's IE is LOWER than N's because pairing one p-orbital in O introduces extra electron repulsion. N's half-filled state is uniquely stable.
Practice this question with progress tracking
Want timed practice with adaptive difficulty? Solve this question (and hundreds more from Classification of Elements & Periodicity) inside The Crucible, our adaptive practice platform.
More JEE Main Classification of Elements & Periodicity PYQs
The property/properties that show irregularity in first four elements of group-17 is/are: (A) Covalent radius (B) Electron affinity (C) Ionic radius (D) First ionization energy Choose the correct…
Electronic configuration of four elements A, B, C and D are given below: (A) 1s2 2s2 2p3 (B) 1s2 2s2 2p4 (C) 1s2 2s2 2p5 (D) 1s2 2s2 2p2 Which of the following is the correct order of increasing…
The atomic number of the element from the following with lowest 1st ionisation enthalpy is:
The correct order of the first ionization enthalpy is:
The correct order of first ionization enthalpy values of the following elements is: (A) O (B) N (C) Be (D) F (E) B