Chemistry S & P Block Elements PMC 2021
PMDC Verified Question 64 of 104
Sodium is not observed in +2 oxidation state because of its
A
High first ionization potential
B
High second ionization potential
C
High ionic radius
D
High electronegativity
Tap any option to test your recall and reveal the step-by-step Propolis autopsy.

Propolis Cognitive Error Autopsy

Official Correct Choice:
Option B: High second ionization potential
Concept:

The likelihood of an element achieving a specific oxidation state depends on the gap between sequential ionization energies.

Solution:

  • Sodium (Na) has the electronic configuration \( 1s^2 2s^2 2p^6 3s^1 \).
  • It effortlessly loses its one valence electron (low first ionization potential) to achieve the incredibly stable, noble gas configuration of Neon (\( 1s^2 2s^2 2p^6 \)). This forms \( \text{Na}^+ \).
  • Trying to remove a second electron requires ripping an electron out of a perfectly stable, fully filled octet shell (the 2p subshell) that is much closer to the nucleus.
  • This requires a gigantic, chemically unfeasible amount of energy (High second ionization potential), which is why \( \text{Na}^{2+} \) never forms in chemical reactions.


Why other options are incorrect:

  • Sodium has a very low first ionization potential and a low electronegativity, which is why it readily forms +1 ions.

Quality & Fidelity Assurance: Every question on BeambePrep is rigorously curated against the official PMDC syllabus with zero filler, zero out-of-syllabus content, and zero typos. When an authentic past paper originally contained a historical mistake or ambiguity from the examining board (such as UHS or NUMS), BeambePrep faithfully reflects the original paper while detailing the nuance and scientific consensus in the autopsy above.

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