Sodium chloride (NaCl) is a white, crystalline solid that’s readily soluble in water. It’s famous for its role as table salt, but this compound has many other uses too. It acts as a wood preservative, chemical reagent, insecticide, and source of fluoride ions. It’s also used in the production of other essential chemicals such as sodium hydroxide, baking soda, and hydrochloric acid.
Unlike most of the alkali metals, elemental sodium doesn’t occur in nature as a free metal. It’s found in the mineral halite and as compounds such as common salt (NaCl). The major use of sodium is in the form of its salts, which are responsible for most of the salinity of seawater. These salts are produced by evaporating seawater or mineral-rich spring waters.
The sodium cation, Na+, is very reactive and forms a wide range of compounds. Normally it exists in the +1 oxidation state, but it is extremely quick to lose its single valence electron, yielding the colorless Na- anion. Consequently, the element can react with almost all inorganic and organic anions to form a variety of salts.
Sodium reacts with most halogen gases, producing salts containing the corresponding halide ions. It also reacts with a number of strong mineral acids to form the corresponding salts. For instance, it reacts with the fumes of nitric acid to produce sodium nitrate and with acetic acid to produce sodium acetate. Moreover, it can be alloyed to an appreciable extent with mercury. This is useful for reactions in which pure elemental sodium would be violently reactive.