Zumdahl • Zumdahl • DeCoste
World of
CHEMISTRY
Chapter 4
Nomenclature
Goals of Chapter 4
1. Name binary compounds of metal and nonmetal
2. Name binary compounds containing only
non-metals
3. Learn names of polyatomic ions and how to
use them in naming
4. Learn common acids and how to name
them
5. Write the formula of a compound when
name is given
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Binary compound: composed of two
elements (bi-)
• Compounds that contain a metal and nonmetal
• Compounds that contain two nonmetals
• Binary ionic compound: contain a positive ion (cation)
and a negative ion (anion)
• To name these compounds, you simply name the
ions
• Positive ion always named first, negative ion
named last
• Example: NaCl (sodium chloride), not ClNa
(Chloride sodium)
• Sum of all charges must equal zero
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Table 4.1
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Type I Binary Compounds: The metal
present only forms one type of cation.
• Group 1 and 2 metals (sometimes Group 3)
• See Table 4.1
• Rules for naming
• The cation is always named first and the anion
named second
• A simple cation (obtained from a single atom)
takes its name from the name of the element
• A simple anion (obtained from a single atom) is
named by taking the first part of the element name
(the root) and adding –ide.
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Examples of Type I Binary Compounds
• NaCl
• Sodium Chloride
• Na+1 combines with Cl-1, sum is zero
• KI
• Potassium Iodide
• K+1 combines with I-1, sum is zero
• MgCl2
• Magnesium Chloride
• Mg+2 combines with 2 Cl-1, sum is zero
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Type II Binary Compounds: The metal present can
form two (or more) cations that have different
charges.
• Many transition metals (some Group 3)
• See Table 4.2
• Rules for naming
• Use basically same procedure as Type I, except
• Use Roman Numerals to designate charge on cations (i.e.
Fe2+ = Iron (II))
• Old system (sometimes still used): Ion with the higher
charge has a name ending in –ic and ion with the lower
charge has a name ending in –ous. For example Fe2+ =
ferrous ion and Fe3+ = ferric ion.
• Do not use Roman numerals for Type I compounds!
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Example of Type II Binary Compounds
• FeCl2
• Chloride is Cl-1, since there are 2 Chloride
ions, the total charge is -2
• Iron is transition metal with unknown
charge
• Sum must be zero, so Fe must be +2
• Proper way to write name is Iron (II)
chloride
• Page 91 has more examples
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Table 4.2
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Type III Binary Compounds: compounds
containing only nonmetals
• See prefixes in Table 4.3
• Rules for naming
• The first element in the formula is named first
• The second element named as though it were an anion
(oxygen → oxide)
• Prefixes are used to denote the numbers of atoms present
(O2 = dioxide)
• The prefix mono- is never used when naming the first
element. (CO is carbon monoxide not monocarbon
monoxide)
• To avoid awkward pronunciation, drop final o or a of prefix
when second element is oxygen
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Some compounds are always referred to
by the common names:
• H2O = water
• NH3 = ammonia
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Figure 4.1: A flow chart for naming binary compounds.
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Polyatomic Ions: charged entities composed of
several atoms bound together
• Entire group has a positive or negative charge
• Oxyanions: contain atom of a given element and different
numbers of oxygen atoms (i.e. nitrate, nitrite)
• Name of one with smaller number of oxygen atoms ends in –ite
(nitrite, sulfite)
• Name of one with larger number of oxygen atoms ends in –ate
(nitrate, sulfate)
• When more than two oxyanions in series, use hypo- (less than – for
fewest) and per- (more than – for most) (hypochlorite, chlorite,
chlorate, perchlorate)
• Rules for naming
• Must recognize the polyatomic ion (break into two parts)
• Use rules similar to naming binary ionic compounds
• Treat polyatomic same as individual element, determine whether
Type I, II, or III
• See flow chart on page 102
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Table 4.4
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Acids: molecules that produce H+ ions when
dissolved in water
•
•
•
•
First recognized by sour taste
Molecule with one or more H+ ions attached to an anion
Naming depends on whether or not oxygen present in anion
Rules for naming
• If anion does not contain oxygen: acid named with the prefix
hydro- and the suffix –ic attached to the root of the name of
the element (i.e. hydrochloric acid = HCl, hydrocyanic acid =
HCN)
• When anion contains oxygen: the acid name is formed from
the root name of the central element of the anion or the
anion name with a suffix of –ic or –ous. When the anion
name ends in –ate, the suffix –ic is used (i.e. H2SO4 =
sulfuric acid). When anion name ends in -ite, the suffix –
ous is used (i.e. H2SO3 = sulfurous acid)
• See flow chart on page 105
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Writing names from formulas
Use naming process
and work backwards
Figure 4.2: Overall strategy for naming
chemical compounds.
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