Answer to Question #170735 in Inorganic Chemistry for Pradeep Chandra Joshi

Question

e first ionization energy of copper is higher than that of potassium whereas the second ionization energy is in the opposite order.

Answer 1

The electron configuration of K and Cu are given below:

K = [Ar]4s¹

Cu = [Ar]3d¹⁰4s¹

Both Cu and K have 1electron in their outermost shell, but Cu also has 10 electrones in its d shell, both elements are in the same period. Therefore, the attraction between the nucleus and electrons in Cu is greater than K.Therefore, atomic size of K is greater than Cu. Greater the atomic size decrease the ionization energy. Therefore, first ionization energy of K is lower than that of Cu.

But After donating one electron the electron configuration of K⁺ and Cu⁺ are:

K⁺ = [Ar]

Cu⁺ =[Ar]4d¹⁰

K⁺ ion has stable electron configuration and its atomic size is smaller than Cu⁺. On the other hand, Cu⁺ have some electrones in its outermost shell. So one can be easily removed. Therefore, the 2nd ionization energy of Cu is lower than the 2nd ionization energy of K.