Question

Arrange the following as per the instruction given in the brackets.
(ii) Na, Li, K (Increasing ionization energy)

Answer 1

Ionization energy is the energy required to remove an electron from the valence shell of an atom in its isolated gaseous state. Ionization energy increases across a period from left to right.

As we go down the group the atomic radius increases, as a result, the distance between the nucleus and electrons increases as well.

Due to this factor, the element loses the valence electrons from its outermost shell more easily and hence the ionization energy decreases.

Therefore the increasing ionization order of the elements is:- $\mathrm{K}<\mathrm{Na}<\mathrm{Li}$.