Arrange the following atoms in order of increasing first ionization energy K, Cs, Rb, Ca — Periodic Table and Periodicity Chemistry Question

💡 Solution & Explanation

Ionization energy is the energy required for the removal of one electron from the isolated gaseous atom. Ongoing down the group, the number of shells increases and ionization energy decreases however, across the period, the number of electrons and nuclear charge also increases resulting in the increase in ionization energy. Therefore, the order of increasing ionization energy is as follows- Cs Rb K Ca Thus, the correct option is (a) Cs, Rb, K, Ca.