Subject: Inorganic Chemistry · Chapter: Main Group Elements · Topic: Main Group Elements – General · Exam: CSIR-NET 2018 · Marks: 2 · Difficulty: Easy
Among the elements Zn, Ga, Ge as As, the one with the lowest first ionization energy is -
(a)As
(b)Zn
(c)Ga
(d)Ge
Answer
Answer (as printed): C
Explanation
$\mathrm{Zn} \rightarrow 3d^{10}4s^{2}$; $\mathrm{Ga} \rightarrow 4s^{2}4p^{1}$; $\mathrm{Ge} \rightarrow 4s^{2}4p^{2}$; $\mathrm{As} \rightarrow 4s^{2}4p^{3}$.Fully filled and half-filled orbitals have higher ionization energy. Hence, $\mathrm{Ga}$ has the lowest first ionisation energy because on removal of an electron, $\mathrm{Ga^{+}}$ achieves a stable noble gas configuration.