NA2

Na2 is the diatomic molecule consisting of two sodium atoms. In contrast to metallic sodium, which exists as a bulk solid, Na2 is a transient species that forms primarily in high-temperature gas phases, flames, or plasmas and is not a stable compound under ordinary conditions.

Chemical bonding and structure: Each sodium atom has one valence electron, and in Na2 those two electrons are shared to form a single covalent bond. The bond order is one, and the bond length tends to be relatively long for a diatomic molecule, reflecting the large atomic radius of sodium. The molecule is weakly bound compared with many other diatomics and can be dissociated by moderate heating or collisions.

Formation, detection, and spectroscopy: Na2 can be produced by vaporizing sodium or by high-temperature reactions in flames and discharge conditions. It has been studied extensively by molecular spectroscopy to characterize its electronic states and transitions. The spectral features of Na2 provide insight into alkali-metal bonding and the electronic structure of light diatomic species.

Occurrence and context: Na2 is not a component of bulk sodium metal or common sodium compounds. It is principally of interest to researchers studying fundamental chemical bonding, gas-phase chemistry of alkali metals, and its role in combustion or plasma environments where sodium-containing species form. Compared with other homonuclear alkali diatomics, Na2 exhibits a longer bond length and relatively low bond dissociation energy, consistent with the properties of large, highly electropositive atoms.