The correct arrangement of the elements in the order of decreasing ionization energies is — Periodic Table and Periodicity Chemistry Question

💡 Solution & Explanation

Generally, Ionization energy increases on moving from left to right in the periodic table due to the decrease in atomic size. So, the order should be Al>Mg>Na However, in case of Aluminium, outermost electron in the 3p orbital is slightly farther away from the nucleus and is well shielded by 3s orbital. Therefore, it requires less ionization energy than removing outermost electron from Magnesium. Hence, the correct order is (d) Mg>Al>Na.