ˈstäk- noun
or stock's system
Usage: usually capitalized 1st S
Etymology: after Alfred Stock, 20th century German chemist
: a system in chemical nomenclature and notation of indicating the oxidation state of the significant element in a compound or ion by means of a Roman numeral that is used in parentheses after the name or part of the name designating this element and ending invariably in -ate in the case of an anion and that is placed above and to the right of the symbol for this element
according to the Stock system nitrous oxide is named nitrogen (I) oxide, ferrosoferric oxide Fe 3 O 4 is iron (II, III) oxide Fe II Fe III 2 O 4 , and potassium manganite is potassium manganate (IV) K 2 Mn IV O 3