JEE Main · 2025 · Shift-ImediumPERI-134

The property/properties that show irregularity in first four elements of group-17 is/are: (A) Covalent radius (B)…

Classification of Elements & Periodicity · Class 11 · JEE Main Previous Year Question

Question

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 answer from the options given below:

Options
  1. a

    B and D only

  2. b

    A and C only

  3. c

    B only

  4. d

    A, B, C and D

Correct Answerd

A, B, C and D

Detailed Solution

🧠 Fluorine breaks every trend in Group 17 The Period 2 element always has a special character because its orbitals are small and electron repulsion is unusually high. For Group 17, Fluorine disrupts covalent radius, electron affinity, ionic radius, and first ionization energy — all four.

🗺️ Why each property is irregular Covalent radius: F is disproportionately small. Electron affinity: Cl >> F due to F's crowded 2p2p cloud. Ionic radius: \ceF\ce{F^-} is smaller than expected compared to the trend. IE1IE_1: F's value is lower than expected from simple period trend relative to other halogens.

All four properties show irregularity. That is option (d).

Answer: (d)\boxed{\text{Answer: (d)}}

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