Question 70: The element expected to form largest ion to achieve the nearest noble gas configuration is :
(1) N
(2) Na
(3) O
(4) F
Answer: Option (1)
Explanation:
To achieve the nearest noble gas configuration, nitrogen gains three electrons to form the nitride ion.
The nitride ion has the electronic configuration 1s^2\,2s^2\,2p^6,
which is the same as neon.
Sodium loses one electron to form \mathrm{Na^+}, while oxygen and fluorine gain two
and one electrons to form \mathrm{O^{2-}} and \mathrm{F^-}, respectively.
Among these ions, \mathrm{N^{3-}} has the highest negative charge
and experiences maximum electron–electron repulsion.
This results in the largest ionic radius compared to \mathrm{O^{2-}},
\mathrm{F^-}, and \mathrm{Na^+}.
Hence, the element expected to form the largest ion is nitrogen,
corresponding to option (1).