A Systematic Approach
Gerhard Lind Metropolitan State College, 1006 11th Street, Denver, CO 80204
Naming inorganic compounds seems to be unsystematic, unim~ortant.and subiect to Dure memorization. This impresgon is ;navoidaLle when the leading textbooks for eeneral chemistnr in the United States are renewed ( I 12). From discu&ions with many colleagues, I alsofeel that many instructors who teach general chemistry do not know the subject of naming inorganic compounds well enough to teach i t adequately and therefore either do a rather poor job or avoid the subject altogether. Being able to name inorganic compounds is, in my opinion, something every student should master after completing one year of college-level general chemistry. Since I am not anadvocate of memorization, I decided to look for the systematics in inorganic nomenclature. I would like to present a semisystematic scheme that I have used successfully for the past four years in our entry-level (college freshmen, general chemistry course. The scheme is divided into three parts: Cations, Anions, and Compounds tsce Figs. 1 3 , . Cations are further subdivided into monatomic andpolyatomic; anions, into monatomic, oxyanions, others and exceptions, and oxyanions containing hvdronen. Compounds are suhdivided into ionic compoun&, iompounds containing hydrogen, and covalent compounds. I am aware t h a t dividing inorganic compounds into "ionic" and "covalent" compounds and then having as a
third category "compounds containing hydrogen" may be a little problematic and artificial,but for the purpose of namiie com~ounds is not. and the fine tuninn can alit ways b;e done in class when the subject is discussGd. Students have eenerallv reacted oositivelv to the as deasured b i t h e students' perscheme, and the re& formance on the subject in examinations are encouraging.
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1917~ ~ d l a lNew York. 1989. a: 11. Whit*", K. W ;Gsiley, K . D: Davis, R. E . Gonrml chpmistry, 3rd . Philadelphia, PA, 1988. 12. Zumdahl, S. S Chemistry, 2nd ed.; Heath: Lexington, MA, 1989. .
Only One Ion
More Than One ion Possible
Rule: Name o element f
Examples: Na* sodium ion Ma2* maonesium ion H' hydiogen ion Comment: The numbero positive f charges is not indicated in the name because it is not necessary
Rule: (a) newer rule: positive charoes indicated bv a roifian numeral. Examples: Fez* iron II) I n o FeJ iron[lll)'ion cu* copper I) ion cu2* copperh)'ion (b) older rule (but st111 used). Latin stem for the element + "ous' for the lesser charge and + 'ic' for the areater charge
(Hg2: ismercury(l1) ion, but that IS a monatomic ion.)
Examples: Cu" Sn" Sn'* gure 1. Scheme for naming cations. Volume 69 Number 6 August 1992
cuprous ion cuprlc I n o stannous ion stannic ion
less oxygen: most oxygen:
Ne ative Ions hnions)
Stem of the element name + 'ide.'...