Question

Why does reactivity increase down the group?

Answer 1

1. Reactivity of an element is its ability to undergo a chemical reaction. This depends on various factors.
2. One of the factors is ionization energy.
3. Ionization energy is defined as the amount of energy required to remove an electron from the outermost shell of an isolated gaseous atom.
4. Considering the elements of Group-1, as we move down a group, the atomic size increases as with every succeeding element in the group, a new energy level is added up.
5. The electrons present in the outermost shells get farther and farther away from the nucleus. It becomes easier to remove an electron from the outermost shell.
6. So, ionization energy decreases down the group.
7. As the ionisation energy decreases, it becomes easier to remove an electron from the outermost shell.
8. So, an element from this group becomes a positive ion more easily and hence is ready to undergo a chemical reaction.
9. Hence, down the group reactivity increases.