Naming Familiar Inorganic Compounds



 

Learning Objective

  • Recognize when it is appropriate to use a common chemical name

Key Points

    • Many frequently used chemicals have familiar common names. A single substance can have several such names.
    • Some common names for chemical substances have historical roots and have been used for thousands of years.
    • Common chemical names are used in spoken or informal written communication by chemists. For some simple compounds, their systematic and common names are the same.

Term

  • common nameThe name by which a species is known to the general public, rather than its taxonomic or scientific name.

Common Names v. Systematic Names

Many chemicals are so much a part of daily life that people know them by their familiar names. Ordinary cane sugar, for example, is more formally known as sucrose, but asking for it at the dinner table by that name will likely be a conversation stopper. Now imagine using its systematic name in the same context: “Please pass the α-D-glucopyranosyl-(1,2)-β-D-fructofuranoside!” But saying “sucrose” would be quite appropriate if you needed to distinguish this particular sugar from the hundreds of other named sugars. And the only place you would come across a systematic name such as the rather unwieldy one mentioned above would be in scientific documentation in reference to a sugar that has no simple common name.

Many common chemical names have very old and intriguing origins, as the following two examples illustrate.

Most people associate the name ammonia (NH3) with a gas with a pungent odor. While its systematic name, “nitrogen trihydride” (which is rarely used), tells you its formula, what it will not tell you is the interesting history of its discovery. Smoke from burning camel dung (the staple fuel of North Africa) condenses on cool surfaces to form a crystalline deposit, which the ancient Romans first noticed on the walls and ceiling of the temple that the Egyptians had built to the sun god Amun in Thebes. They named the material “sal ammoniac,” meaning “salt of Amun.” In 1774, Joseph Priestly (the discoverer of oxygen) found that heating sal ammoniac produced a gas with a pungent odor, which T. Bergman named “ammonia” eight years later.

Arabic alchemy has given us a number of chemical terms. For example, alcohol is believed to derive from the Arabic al-khwl or al-ghawl, which originally referred to a metallic powder used to darken women’s eyelids (kohl). Alcohol entered the English language in the 17th century with the meaning of a “sublimated” substance, then changed to mean the “pure spirit” of anything, and only became associated with “spirit of wine” in 1753. Finally, in 1852, it become a part of chemical nomenclature that denoted a common class of organic compound. But, it is still common practice to refer to the specific substance CH3CH2OH as “alcohol” rather than by its systematic name, ethanol.

General Practices in Naming

The general practice among chemists is to use the more common chemical names whenever it is practical to do so, especially in spoken or informal written communication. Many of the “common” names are known and used mainly by the scientific community. Chemical substances that are employed in the home, the arts, or in industry have acquired traditional or “popular” names that are still in wide use. Many, like sal ammoniac mentioned above, have fascinating stories behind their names.

Sulfuric AcidThe historical name for sulfuric acid is “oil of vitriol”. Medieval European alchemists prepared it by roasting “green vitriol” (iron (II) sulfate) in an iron retort. Its chemical formula is H2SO4.