Given below are two statements: Statement I: Fluorine has most negative electron gain enthalpy in its group. Statement II: Oxygen has least negative electron gain enthalpy in its group. In the light of the above statements, choose the most appropriate from the options given below.

Solution & Explanation

Related Formula

Electron Gain Enthalpy (ΔegH) trends in Group 16 and Group 17 elements.

Core Logic

Evaluating both statements:

  • Statement I is false: Due to its small size, strong inter-electronic repulsions in the compact 2p subshell of Fluorine limit incoming electrons compared to Chlorine. As a result, Chlorine (Cl) has the most negative electron gain enthalpy in Group 17.
  • Statement II is true: Similarly, the exceptionally small size of the Oxygen atom creates intense electron-electron repulsions. Consequently, it has the least negative electron gain enthalpy among all elements in Group 16.
Step 1: Final Assessment

Therefore, Statement I is false while Statement II is true, matching choice (4).

Pattern Recognition

Third-period elements (Cl, S) exhibit more negative electron gain enthalpies than their second-period counterparts (F, O) due to lower inter-electronic repulsion in their larger valence shells.

Chapter Mix

Class 11 Chemistry: Classification of Elements and Periodicity

Reference Study Guides

Classification Of Elements And Periodicity

More Classification of Elements and Periodicity Previous-Year Questions — Page 8

Q70 jee_main_2024_31_jan_morning Electron Gain Enthalpy
The correct sequence of electron gain enthalpy of the elements listed below is A. Ar B. Br C. F D. S Choose the most appropriate from the options given below:
  • A. C > B > D > A
  • B. A > D > B > C
  • C. A > D > C > B
  • D. D > C > B > A

Solution

Core Logic

Electron gain enthalpy (ΔegH) values are considered with their signs when ordering from largest to smallest algebraically.

ElementΔegH (kJ/mol)
F-333
S-200
Br-325
Ar+96

Arranging these algebraically from highest to lowest: +96 > -200 > -325 > -333 Thus, Ar > S > Br > F, which corresponds to A > D > B > C.

Pattern Recognition

Noble gases always have positive electron gain enthalpies (highest algebraically). Halogens have highly negative values (lowest algebraically). Fluorine is highly negative, Bromine is slightly less negative. Sulfur sits in between.

Chapter Mix

Class 11 Chemistry: Classification of Elements and Periodicity in Properties

More Classification of Elements and Periodicity Questions — jee_main_2024_29_january_evening

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