On moving down a group in the periodic table, which of the following…
2019
On moving down a group in the periodic table, which of the following statements are correct?
A. Electronegativity decreases.
B. Atomic radius increases.
C. Ionisation enthalpy decreases.
- A.
A, B and C
- B.
Only A
- C.
Only B
- D.
Only C
Attempted by 2 students.
Show answer & explanation
Correct answer: A
Concept
On moving down a group, each successive element has an additional electron shell. The greater distance and increased shielding reduce the effective attraction experienced by valence electrons. Thus atomic size grows, while the tendency to attract or hold outer electrons generally declines.
Application
Statement A follows because the weakened attraction for a shared electron pair generally lowers electronegativity.
Statement B follows because an additional occupied shell makes the atomic radius larger.
Statement C follows because increased shielding makes removal of the outer electron easier, so ionisation enthalpy generally falls.
Contrast
Only A ignores that shell addition also changes atomic size and electron removal.
Only B notices the size trend but omits the accompanying changes in attraction and electron removal.
Only C considers electron removal but omits the simultaneous size and electronegativity trends.
Cross-check
Comparing successive members of a group gives the same pattern: the lower member is larger and generally has lower electronegativity and ionisation enthalpy.
Therefore, statements A, B and C are all correct.