Nomenclature
Chapter 5
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5.1 Naming Compounds
• Many compounds have common names:
Ex:
H2O = water
NH3 = ammonia
CH4 = methane
• There must be system for naming
(nomenclature) the thousands of known
chemical compounds.
• Compounds named in this chapter:
 Binary compounds -- those composed of two
elements:
• Metal with a nonmetal (ionic)
• Two nonmetals (nonionic)
 Polyatomic compounds -- composed of a
metal and a PA anion, or two PA ions.
 Acids -- H+ and an anion.
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5.2 Naming Compounds that
Contain a Metal and a
Nonmetal
• Binary ionic compounds contain a metal
cation and a nonmetal anion.
• Rules for naming:
 Name the metal cation first, then name
the nonmetal anion.
 The metal cation name is the metal
name.
 The nonmetal anion name uses the
root of the element name and adding –
ide suffix.
See table 5.1
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 For metals that can form more than
one type of cation -- such as transition
metals, and Group 4A metals -- the
cation name is the metal name
followed by a Roman numeral in
parentheses to indicate its charge.
 See Table 5.2
• The net charge on an ionic compound is
always zero.
• Examples: text pg 126-127, 129
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5.3 Naming Binary Compounds
Containing only Nonmetals
•
These compounds do not contain ions.
•
Rules for naming:
 Name the first element in formula
using the full name of the element.
 Name the second element in the
formula as if it were an anion (root
name plus –ide suffix).
 Use a prefix in front of each name to
indicate the number of atoms. (See
Table 5.3)
 Never use the prefix mono- on the
first element.
 Drop last “a” in the prefix if the name
begins with vowel.
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Table 5-3
Subscript
1
Prefix
mono(Not on first element)
2
3
4
5
6
7
8
ditritetrapentahexaheptaocta-
Examples: see pages 132 -133
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5.4 (Skip)
5.5 Naming Compounds that
Contain Polyatomic Ions
• Polyatomic ions are charged entities
composed of several atoms bound
together.
• Must memorize name, formula and
charge.
 See list of PA ions given you, or Table 5.4
 Oxyanions – polyatomic anions that contain a
given element with different numbers of
oxygen.
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• Polyatomic compounds:
 are ionic compounds because they
contain ions bonded together.
 are not binary compounds because
they contain more than two
elements.
 Contain a metal combined with a
polyatomic ion or can be composed
of two polyatomic ions
 Examples:
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• Rules for naming:
 Name metal cations as in binary ionic
compounds. (Use Roman numerals
when necessary.)
 Use the name of the polyatomic ion
part of the compound as written.
 Put parentheses around polyatomic
ions when more than one is present.
 Examples:
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5.6 Naming Acids
• Acids are compounds that produce H+
cations and an anion when dissolved in
water.
• Rules for naming: see handout
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5.7 Writing the Formulas from
the Names
•
For binary ionic compounds (metal and
a nonmetal), polyatomic compounds,
and acids:
 Determine the ions present.
 Determine the charges on the cation
and anion.
 Balance the charges to get the
formula subscripts.
•
For binary compounds composed of
two nonmetals, use the prefixes to
determine the formula subscripts.
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