Which Is The Most Reactive Element In The Periodic Table?

The reactivity of an element is a function of how easily an element loses or gains electrons. To determine an element's reactivity, we can learn a lot from the periodic table, and its particular trends.

The first element in the halogen group is fluorine. It’s a pale yellow, diatomic, highly corrosive, flammable gas with a pungent odor. Its atomic number is 9, and has a jam-packed 7 electrons in its valence shell. Moreover, it resides in the second row, which implies that all its 9 electrons are somehow crammed into only 2 shells.

A 7-electron valence shell requires it to gain only a single electron to complete its final shell and achieve stability, which isn’t a big feat when you consider its small size and vigorous nuclear pull. Fluorine is identified as the most electronegative element in the periodic table, making it the strongest oxidizing agent.