Why the Names?

How do we clearly and unmistakably identify compounds?

B4.42 Spotlight on a stool
The phrase “in the limelight” means being the centre of attention and was first coined in the 1800s. At that time, a process was invented to spotlight actors on a stage. The process involved heating a piece of quicklime in a flame of burning oxygen and hydrogen. An intense white light was produced that was used to spotlight key actors on the stage.

You probably understand and recognized the substances hydrogen (H) and oxygen (O) but are at a loss for what quicklime is. This was a common problem in the early days of chemistry. Compounds were not named in a systematic way but instead named randomly by their discoverer. The naming was perhaps based on the location of the discovery, the use of the compound, the method of preparation, the appearance of the substance, or a myriad of other reasons. These random names lead to confusion about the identity of the compounds. For example, if the materials list for a chemistry lab included lye, muriatic acid, oil of vitriol, quicksilver, limestone, saltpeter, and slaked lime would you have any idea what chemicals you were working with and thus what precautions you should take?

  Digging Deeper

© Wikimedia Commons
B4.43 Caustic soda

Visit this website that lists many common names of substances. Their scientific and chemical formulas are included. https://www.spectro.in/Chemical-Compounds.html

Learn More

Common names do not indicate the composition of the substance. For example, table salt gives no indication of the constituent elements, whereas the systemic name, sodium chloride, does. Starting in the 1800s, many chemists supported the idea of and put forth recommendations for a naming system. In 1919, the International Union of Pure and Applied Chemists (IUPAC) was established and a set of guidelines were developed for naming substances.

Naming compounds using a fixed set of rules is important so that all compounds are recognized globally by the same name to avoid confusion and misunderstanding. In Science 10, it is expected that you learn the rules and use IUPAC names, instead of common names, for most compounds. There are a few compounds that have widely recognized and used common names, such as water (H2O), ammonia (NH3), and table sugar (C12H22O11).

  Read This

Please read pages 40 and 41 in your Science 10 textbook. Make sure you take notes on your readings to study from later. You should focus on the confusion that is created by the use of common compound names. Remember, if you have any questions or you do not understand something, ask your teacher!

  Practice Questions

Complete the following practice questions to check your understanding of the concept you just learned. Make sure you write complete answers to the practice questions in your notes. After you have checked your answers, make corrections to your responses (where necessary) to study from.

  1. Why was there a need to create a unified set of rules for naming compounds?

    There was a need for unified naming rules to ensure that chemical names are unambiguous (i.e., a name can only refer to one substance.) These standards make it easier to use chemicals; otherwise, scientists everywhere could use different names for the same compound. That could make for some very dangerous situations in chemistry laboratories.
  2. Research! What is the IUPAC name and chemical formula of quicklime?

    calcium oxide, CaO
  3. Research! What is the IUPAC name and chemical formula of lye?

    Lye, commonly used in soapmaking, is used to refer to sodium hydroxide (NaOH) or potassium hydroxide (KOH)