In case of isoelectronic species the size of $\mathrm{F}^{-}$, Ne and $\mathrm{Na}^{+}$ is affected by:

(A) Principal quantum number (n)

(B) None of the factors because their size is the same

(C) Electron-electron interaction in the outer orbitals

JEE Main · 2024 · 01 Feb 2024 · Shift 1 · Classification of Elements and Periodicity

In case of isoelectronic species the size of

F^{-}

, Ne and

Na^{+}

is affected by:

(A)Principal quantum number (n)
(B)None of the factors because their size is the same
(C)Electron-electron interaction in the outer orbitals
(D)Nuclear charge (z)✓ Correct

Answer: (D)

Solution

^{-}

, Ne and Na

^{+}

are isoelectronic (each has 10 electrons, configuration

1 s^{2} 2 s^{2} 2 p^{6}

). With the same number of electrons, their size is governed entirely by the nuclear charge: higher nuclear charge pulls the same electron cloud in more tightly. Since

Z

(F)

<

Z

(Ne)

<

Z

(Na), size decreases in that order. So size is affected by nuclear charge (

Z

JEE Main · 2024 · 01 Feb 2024 · Shift 1 · Single correct option

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