Question

Although most of the elements in 'd' block has 2 electrons in their valence 's' shell yet their ionization energies are higher than Group 2 elements.

Answer 1

The atom's size decreases across the period. So, the "ionization energy" of elements "increases" as we move towards right from left in the "Periodic table". Due to the increased "nuclear charge", the valence electrons move "closer to the nucleus" of the atom when moving from "left to right". This makes the "force of attraction" between the "nucleus" and "electrons" to increase, so that to "remove an electron" from the "valence shell" more energy is required. Hence, the ionization energy of "'d' block elements" is "higher" than the Group 2 elements.