Chemistry Reference
In-Depth Information
Lesson 5-1 Review
Use your knowledge of the information found in the Rules for Assign-
ing Oxidation Numbers to assign oxidation numbers to the requested ele-
ments in numbers 1-8.
1. What is the oxidation number shown by nitrogen in a molecule of N
2
?
2. What is the oxidation number of chlorine in a formula unit of NaCl?
3. What is the oxidation number shown by potassium in K
2
S?
4. What is the oxidation number shown by oxygen in a molecule of water?
5. What is the oxidation number of calcium in CaO?
6. What is the oxidation number of sulfur in BaSO
4
?
7. What is the oxidation number of sulfur in Li
2
SO
3
?
8. What is the oxidation number of carbon in CaCO
3
?
Lesson 5-2: Writing Chemical Formulas
We are now ready to go over the very important skill of writing chemi-
cal formulas. Recall the analogy that I made use of in Chapter 3, when I
referred to the chemical formulas as the “words” that make up the chemi-
cal equations that you will need to learn how to write. These chemical for-
mulas, in turn, are made up of the elemental symbols, which represent the
“letters” in the language of chemistry. This will be one of the most impor-
tant lessons that you will cover in chemistry. Learning this lesson well will
allow you to develop the confidence to succeed in this subject. I urge you to
take the time to master this topic by practicing as many examples that you
can get your hands on.
The tools that you use for this lesson will be one or more oxidation
tables. These tables look different in different topics, but the information
that they contain is the same. Some periodic tables will include oxidation
numbers, so your instructor may ask you to work from that. It is probably
more likely that your instructor will give you a separate set of tables with
oxidation numbers, so I will follow that format in this text. Often, the oxi-
dation numbers are divided into two tables, one for monatomic (single-
atom) ions and one for polyatomic (multiple-atom) ions, as shown here. It
doesn't matter where you get the information from, as long as you can use
the oxidation numbers to write proper chemical formulas.
