Question

Name an Alkali metal having the lowest ionization energy.

Answer 1

1. Ionization energy- It is the minimum energy needed to remove the valence electron of an isolated neutral atom. The more difficult it is to remove the electron, the higher is the ionization energy.
2. Alkali metals- Group 1 elements are known as Alkali metals. Their general valence shell configuration is ns¹. They include Hydrogen (H), Lithium (Li), Sodium (Na), Potassium (K), Rubidium (Rb), and Cesium (Cs).
3. Trend of ionization energy across the group- As we move down the group, the size of the atom increases and so is the distance between the valence shell electron and the nucleus, Thus, it becomes easier to remove the valence electron on moving down the group.
4. Hence, ionization energy decreases on moving down the group.
5. Cesium is the alkali metal having the lowest ionization energy.