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Introductory Chemistry (X11)

Naming chemicals. Page 1


Introduction

As you begin to study chemistry, most of the chemicals you will need to name consist of two parts. Example: NaCl consists of sodium ion and chloride ion; it is named sodium chloride. What complicates matters for a beginner is that there are three rules for assigning the correct name. Your first job in assigning a name is to figure out which of the three rules applies.

This is an exercise in naming these two-part compounds. To "force" you to explicitly think first about which rule applies, the exercise is broken into two steps. In step 1, you are asked simply to classify the compound. Do this step, and check yourself on the classifications. Then go on to step 2, and name the compounds, guided by the classifications. Then check yourself on the naming. Both answer sheets posted here give explanations.

This exercise is also available as a Word DOC file (the form in which it is used for classes, as a handout). This web page gives an expanded version of the introduction; what is written on the handout may be sufficient. If you use the DOC file, you can check your answers here; links to the answer sheets are at the bottom of this page. The Word DOC file is at "Naming chemicals" doc file. However, visitors may choose to just use this web page, which really stands on its own.

   Bottom of page; answer keys, return links and contact information

Each question below gives the formula for a chemical. For each...
* First, determine which type of chemical it is. The types are listed in the green box below; these types correspond to the three naming rules.
* Check yourself for this step, using the answer sheet posted here. Page 2: answer sheet for "type".
* Then, name the chemical according to the rules for that type.
* Check yourself for this step, using the answer sheet posted here. Page 3: answer sheet for "name".

 
Types of compounds (for deciding how to name them):

1. Ionic, with "predictable" cation. (Name: just name the cation and the anion.)
2. Ionic, with "unpredictable" cation. (Name: As above, but include the cation charge = oxidation number, as a roman numeral.) (Don't worry about the "old system" -- using -ous and -ic suffixes.)
3. Covalent (two non-metals). (Name: Use Greek prefixes to show how many of each atom.)

The distinction between "predictable" and "unpredictable" cations (types 1 vs 2) ultimately requires that you remember which are which. However, it is a useful "rule of thumb" for getting started that metals in the main groups give predictable cations (predictable from the group number), whereas transition metals give unpredictable cations (i.e., the metal has more than one common cation). This rule-of-thumb is not completely correct, in either direction, as you can see from Fig 6.3 of Cracolice (2/e and 3/e); however, it is reasonably helpful at the start, and will be adequate for all the problems in this set.

This is a brief explanation; see the book for details and examples. In Cracolice (2/e and 3/e), most of this is in Sect 6.3 and 6.4, although the complex (polyatomic) ions are discussed in later sections.


To do. For each chemical listed, classify it into one of the three types listed above. Check yourself, on Page 2, the answer key, which includes explanations. Be sure you understand why each chemical is classified the way it is. After classifying all these chemicals correctly, then you can name them, and check your names (Page 3).

You may be able to check yourself as you go. Each item contains a "link" labeled "answer". Move the cursor over that link; a brief answer will appear, after a momentary delay, in a balloon right near the link. These are only brief answers; for the full answers, with explanations, see Page 2, as discussed above.

There is a "text box" available, so that those who work on this online can write their answers on the screen. Just position your cursor in the text box, and type or delete characters as you wish. The text box is entirely for your convenience; there is no computer processing of anything you type.

You may -- and should -- use a periodic table (PT).

I encourage you to try to go through this set in the order given. To some extent, the order gives hints. Except possibly for the last one, these are all intended to be straightforward examples of the rules.

The questions:

question
number 		formula type -- You fill in this column, using the
types listed above. See To do, above.
1 NaF answer
2 CuF answer
3 CuF2 answer
4 CuS answer
5 Cu(NO3)2 answer
6 ClO2 answer
7 Cl2O answer
8 N2S5 answer
9 CaSO4 answer
10 FeSO4 answer
11 Fe2(SO4)3 answer
12 (NH4)2SO4 answer

Notes

You can get more problems for practice from the textbook. I encourage you to follow the approach here: first figure out which type of chemical it is, then name it. By using this two step approach, we can see where you have a problem.

The ions shown here are important ones, which you should know. (After all, I wrote these questions, so I chose the ions.)

Top of page

The pages of "Naming chemicals":
Page 1 Page 2 Page 3
Introduction, and the questions Answers for "type of compound" Answers for "name of compound"
This page Next page; check your answers for "type"  

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Chemistry practice problems. Includes link to the Naming Chemicals handout, under Self-help worksheets. Also includes Practice quizzes, Sample tests, Homework.

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Last update: January 18, 2009

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