The element that has only one valence electron is hydrogen (H). Hydrogen is unique because it has a single electron in its outermost shell, making it similar to the alkali metals in terms of its valence electron configuration.
However, hydrogen cannot be considered an inert gas like helium (He), neon (Ne), argon (Ar), and other noble gases. This is because the inertness of noble gases arises from their full electron shells, which makes them highly stable and unlikely to form chemical bonds with other elements. In contrast, hydrogen has a single electron and can readily form bonds with other elements to achieve a more stable electron configuration.
While hydrogen can exist as a diatomic molecule (H2), where two hydrogen atoms share their electrons, it is still highly reactive compared to inert gases. It readily reacts with elements such as oxygen, chlorine, and fluorine to form compounds like water (H2O), hydrogen chloride (HCl), and hydrogen fluoride (HF).
Therefore, due to its reactivity and inability to achieve a stable electron configuration on its own, hydrogen cannot be considered an inert gas like helium, neon, argon, and others.