Question

After the transition elements, $(IE{)}_1$ drops abruptly in $Ga,In$ and $Tl$. This is due to

• A. Decrease in effective nuclear charge
• B. Increase in atomic radius
• C. Removal of an electron from the singly occupied $np-$ orbitals of higher energy than the $ns-$ orbitals of $Zn,Cd$ and $Hg$
• D. None of the above

Answer 1

The correct option is C Removal of an electron from the singly occupied $np-$ orbitals of higher energy than the $ns-$ orbitals of $Zn,Cd$ and $Hg$

The general electronic configuration of $Ga,InandTl$ is $n{s}^2(n-1)d^{10}n{p}^1$. In the formation of $G{a}^{+}/I{n}^{+}/T{l}^{+}$ unpaired electron from $np$ orbital is removed.

While general electronic configuration of $Zn,CdandHg$ is $n{s}^2(n-1)d^{10}$. So in the formation of $Z{n}^{+}/C{d}^{+}/H{g}^{+}$, paired electron from ns orbital is removed.

Since, energy of $np>ns$ and unpaired electron is removed more easily than paired electron, hence following the transition elements, $(IE{)}_1$ drops abruptly in $Ga,InandTl$