Which of the following ionic species has the greatest proton affinity to form stable compound?
Which of the following ionic species has the greatest proton affinity to form stable compound?
$\mathrm{NH}_2^{-}$
$\mathrm{F}^{-}$
$1^{-}$
$\mathrm{HS}^{-}$
Solution
Proton affinity decreases in moving across the period from left to right due to increase in charge. Within a group the proton affinities decreases from top to bottom.
$\Rightarrow$ Proton affinity $\rightarrow$ Nitrogen family $ > $ Oxygen family $ > $ Halogens