Question

Why is there a large increase in ionization energy of the alkali metals?

Answer 1

Ionization energy:

1. Any of the elements found in Group IA of the periodic table like Lithium, Sodium, Potassium, Rubidium, Cesium, and Francium are alkali metals. They have a general electronic configuration ${\mathrm{ns}}^1$
2. They are monovalent, electropositive, and highly reactive metals that produce extremely alkaline hydroxides.
3. Ionization energy or ionization potential is the amount of energy needed to remove an electron from an isolated atom or molecule.
4. The electrons are closely bound and more energy is required for ionization, which results in a significant rise in the ionization energy of the alkali metals.
5. This is because the electrons in the same principal quantum shell do not entirely shield the protons' increasing nuclear charge.

Therefore, because of tightly bound electrons in the last shell, there is a large increase in ionization energy of the alkali metals