Chemistry · Periodicity of Elements and Periodic Properties

NEET (UG) 2023 — Question 66

The element expected to form largest ion to achieve the nearest noble gas configuration is :

Option A:
F
Option B:
N
Correct
Option C:
Na
Option D:
O

Answer: B

Step-by-step solution

Elements form ions to achieve noble gas configuration: F forms $\ce{F^-}$ , N forms $\ce{N^{3-}}$ , O forms $\ce{O^{2-}}$ , Na forms $\ce{Na^+}$ . All these ions have 10 electrons (isoelectronic with neon). For isoelectronic species, ionic radius increases as nuclear charge (number of protons) decreases. Nuclear charges: $\ce{Na^+}$ (11), $\ce{F^-}$ (9), $\ce{O^{2-}}$ (8), $\ce{N^{3-}}$ (7). Thus, ionic radius order: $\ce{N^{3-} > O^{2-} > F^- > Na^+}$ . Therefore, nitrogen (N) forms the largest ion.

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Exam: NEET (UG) 2023
Paper: 2023 paper
Subject: Chemistry
Chapter: Periodicity of Elements and Periodic Properties
Topic: Valency, Diagonal Relationship, Inert Pair Effect & Other Miscellaneous Properties