d. Rule of Crossing Valences. A convenient rule for determining what
subscripts are necessary in writing formulas is the rule of crossing valences. This rule
states that one can take the valence of the element at the left and make it the subscript
of the element at the right, and in like manner take the valence of the element at the
right and make it the subscript of the element at the left. For example:
Fe+3
SO4 2
becomes Fe2(SO4)3
Section II. RULES OF INORGANIC NOMENCLATURE
1-8.
INTRODUCTION
a. This section discusses how to name a compound from its formula. The
interrelationship of names and formulas is very important to you. You will be required to
recognize both, in interpreting, preparing, and using these chemicals.
b. This section is in the format of programmed instruction. Each frame
presents some material, and then asks some questions in which you apply the material
presented. The correct answers follow so that you can check your answers for
accuracy. It is important that you use a piece of paper to cover the answers as you
work the program. You should fill in the answers as you work each frame and then
check your answers. If you answered any questions incorrectly, go back and review the
frame so that you understand the correct answer.
1-9.
GENERAL TERMS
There are several general terms we use that give us information about inorganic
compounds. To describe the number of different elements in a compound we use the
terms binary, ternary, and quaternary. A binary compound contains two different
elements, such as NaCl. A ternary compound contains three different elements, such
as H2SO4. A quaternary compound contains four different elements such as NaHCO3.
a. Questions.
(1) CO2 is a ______________________ compound because it contains
________ different elements.
(2) Al(OH)2Cl is a ______________________ compound because it
contains ________ different elements.
(3) KNO3 is a ______________________ compound because it contains
________ different elements.
MD0803
1-19
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