<P> The most common oxidation state for sodium is + 1 . It is generally less reactive than potassium and more reactive than lithium . Sodium metal is highly reducing, with the standard reduction potential for the Na / Na couple being − 2.71 volts, though potassium and lithium have even more negative potentials . </P> <P> Sodium compounds are of immense commercial importance, being particularly central to industries producing glass, paper, soap, and textiles . The most important sodium compounds are table salt (Na Cl), soda ash (Na CO), baking soda (Na HCO), caustic soda (NaOH), sodium nitrate (Na NO), di - and tri-sodium phosphates, sodium thiosulfate (Na S O 5H O), and borax (Na B O 10H O). In compounds, sodium is usually ionically bonded to water and anions, and is viewed as a hard Lewis acid . </P> <P> Most soaps are sodium salts of fatty acids . Sodium soaps have a higher melting temperature (and seem "harder") than potassium soaps . </P> <P> Like all the alkali metals, sodium reacts exothermically with water, and sufficiently large pieces melt to a sphere and may explode . The reaction produces caustic soda (sodium hydroxide) and flammable hydrogen gas . When burned in air, it forms primarily sodium peroxide with some sodium oxide . </P>

Sodium or potassium salts of heavier fatty acids are called