The Stock system name for the ionic compound NaCL is sodium chloride. Stock nomenclature for inorganic compounds is a system used for naming compounds that contain a multivalent metal, a metal capable of forming more than one type of ion.
In this system, the oxidation state or number of the metal is indicated in parentheses by Roman numerals. For example, FeCl2 is written as iron(II) chloride, and FeCl3 is written as iron(III) chloride. In the case of sodium chloride, the name would be sodium(I) chloride(?I). However, the name is long, and such usage is rare.
The system was developed by the German chemist, Alfred Stock. In his own words, he believed the system to be “simple, clear, immediately intelligible, capable of the most general application.”