CHEMICAL TERMINOLOGY 

C HEMICAL TERMINOLOGY AND USAGE are number as a left superscript, as 14C, is gradually 

governed by the International Union of Pure and becoming universal. Ratios, however, are generally 

Applied Chemistry (IUPAC). Various commissions more readable if the superscript follows the symbol, 

within the IUPAC periodically update, revise, or as Rb85/Rb87. Thus, an admixture of the two practices, 

clarify terminology in many areas of specialty. These even in the same paper, seems permissible. If the 

revisions appear as recommendation articles in "Pure author chooses to use the form Rb85/Rb87, it Should be 

and Applied Chemistry," the official journal of the used consistently for all ratios. Where the full name 

IUPAC. Recommendations published through 1979 of an element is used in text matter, the mass numare available in a handbook (International Union of ber is presented with a hyphen, as carbon-14. The 

Pure and Applied Chemistry, 1979), which is com- atomic number is commonly omitted but, if used, is 

monly referred to the "green book" of the IUPAC. written as a left subscript: 1:~. Ionic charge is always Recent editions of the Chemical hbber Company's indicated as a superscript numeral followed by a plus (CRC) "Handbook of Chemistry and Physics" (Weast, or minus sign. 1984) also contain much of this information. IUPAC rules call for use of Greek terms for 

Chemical names, rather than symbols, are generally adjectives and prefixes pertaining to valences and 

used in text except for the following: other stoichiometric properties. Thus "monovalent," 

"divalent," "trivalent," "tetravalent," "pentavalent," 1 In a list, if the name list exceeds five elements, ,d "hexavalent" are preferred. atomic symbols should be used for the sake of The results of chemical analyses of rocks and 

brevity: Analysis shows the presence of Mg, Sbs minerals are generally reported in terms of weight Rb, Pt, Ag, and Au. percent of the oxides present. This practice naturally 2. In a complex term: Ca-Mg-SO3-NO, solution. leads geologists to describe chemical changes in terms 

3, In proximity: Ca+ and Mg+ ions combine with of the oxides, as "The introduction of silica and aluC0,- and SO4-, respectively. mina during metasomatism * * *." This usage is generally proper, but inconsistencies may arise because 

Symbols should also be ~ed in tables and equations there is no convenient term for total iron oxides. Conand within text where failure to do so would result sider, for example the sentence "Silica, magnesia, and 

in complex or ambiguous terms. A table of atomic iron were introduced," in which two oxides and one 

names, symbols, and weights (International Union of element are mentioned. Such difficulties can be 

Pure and Applied Chemistry, 1984) is reproduced in avoided by describing chemical changes in terms of 

table 2, in the section on "Abbreviations, Signs, and elements or perhaps by using the 

Symbols." for the several oxides. 

Correct usage of chemical symbols as dictated by Any table reporting chemical analyses should clearly the International Union of Pure and Applied distinguish between reporting oxides and ions. Most 

Chemistry is illustrated as follows: researchers follow the reporting scheme used in Deer 

and others (1966) in which analyses are reported from 

$a: highest to lowest oxidation-state cations (as oxides) 

followed by anions. The rare earth elements should 

Field Contents never be referred to as rare earths. A rare earth is 

1 ------ mass number an oxide of a rare earth element; hence, the two 

2-- atomic number (usually omitted) terms are not interchangeable. Rare earths are 

3- charge generally reported together as a group. 

4 ---- number of atoms The words "analyze" and "analysis" are often misused for "determine" or "determination." A report of 

Isotopes are commonly designated by the atomic "15 copper analyses" properly refers to 15 samples of 

number (the number of protons in the nucleus) and copper ore that were analyzed for copper or for other 

the mass number (the sum of the protons and neu- elements; a report on the copper content of 15 rocks 

trons in the nucleus). The custom of writing the mass should refer to "15 copper determinations." 

Chemical terminology 
The spellings "sulfur," "sulfide," and "sulfate" contains niobium as an essential element, is still called 

have replaced the older spellings "sulphur," "sul- columbite). "Mercury" is the correct term for the 

phide," and "sulphate." "Beryllium (Be)" and chemical element, but "quicksilver" is correct in 

"niobium (Nb)" have replaced the names "glucinium technical or industrial usage. 

(GI)" and "columbium (Cb)," but "columbium" is still The term "lime" (CaO) is commonly misused for 

correct in some technical references such as to ferro- calcium (Ca). "Soda," meaning sodium carbonate 

columbium alloys (and the mineral columbite, which (N+CO,), and "potash," meaning potassium carbonate (GCO,), are also commonly misused, both when 

the elements are meant, as in "potash feldspar," and 

when the oxide is meant, as in "The analysis shows 

4.35 percent potash," meaning potassium oxide (K,O). 

Be explicit, therefore, and write "potassium oxide" 

and "potassium carbonate" when referring to these 

compounds. In technical usage, the term "potash," as 

in "potash deposits of the United States," is deeply 

entrenched and should be retained. 

92 Chemical terminology