Why is Rubidium More Reactive Than Sodium?

Rubidium is more reactive than sodium primarily due to its electron configuration and position in the periodic table.

Both sodium (Na) and rubidium (Rb) belong to Group 1 of the periodic table, known as the alkali metals. They each have one electron in their outermost electron shell, which makes them highly reactive as they seek to lose this electron to achieve a stable electron configuration.

However, the key difference is their atomic structure:

1. Position in the Periodic Table: Sodium is in the third period, while rubidium is in the fifth period. This means rubidium has more electron shells (five) compared to sodium’s three. The increased distance of the outer electron from the nucleus in rubidium results in a weaker electrostatic attraction between the positively charged nucleus and the negatively charged outer electron.
2. Ionization Energy: The reactivity of an element increases with decreasing ionization energy, which is the energy required to remove an electron. Rubidium has lower ionization energy than sodium because its outer electron is farther from the nucleus and experiences more shielding from the inner electron shells. This makes it easier for rubidium to lose its outer electron compared to sodium.

As a result of these factors, rubidium is more willing to participate in chemical reactions by losing its outer electron, making it more reactive than sodium.