<P> In chemistry , Roman numerals are often used to denote the groups of the periodic table . They are also used in the IUPAC nomenclature of inorganic chemistry , for the oxidation number of cations which can take on several different positive charges . They are also used for naming phases of polymorphic crystals , such as ice . </P>
when do you use the roman numerals in chemistry
to denote the groups of the periodic table