Question

Value of shielding constant $\sigma$ for $Ne$ is $4.15$ . Find the effective nuclear charge on $N{a}^{+}$ and $F^{-}$ , respectively.

• A. $4.85,6.85$
• B. $5.85,6.85$
• C. $6.85,4.85$
• D. $4.85,4.85$

Answer 1

Answer: (C)

$Ne,N{a}^{+},F{e}^{-}$ are all isoelectronic species..
Electronic configuration of each species is given as
$\_{10}^{}Ne:1s^2,2s^{2}2p^6\_{11}^{}N{a}_{}^{+}:1s^2,2s^{2}2p^6\_9^{}{F}_{}^{-}:1s^2,2s^{2}2p^6$
All have shielding constant.
Also, $Z_{eff}=Z-\sigma$
$\therefore Z_{eff}\left({\left(Na\right)}^{+}\right)=11-4.15=6.85$
and $Z_{eff}\left(F^{-}\right)=9-4.15=4.85$