Transcript Nomenclature Chapter 5 1

Nomenclature
Chapter 5
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Common Names - Exceptions
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H2O = water, steam, ice
NH3 = ammonia
CH4 = methane
NaCl = table salt
C12H22O11 = table sugar
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Naming Starts with Classifying
Compounds
• Binary Compounds = only 2 elements
• Compounds containing polyatomic ions
• Acids = formula often starts with H
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Classifying Binary Compounds
• Compounds containing a metal and a nonmetal
are binary ionic
– Type I and II
• Compounds containing two nonmetals
– Type III
• Compounds containing H and a nonmetal =
Acids
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Binary Ionic
• Made of metal cation and nonmetal anion
• Name by naming the ions
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Metal Cations
• Type I
– Metals that can only have one possible
charge
– Determine charge by position on the
Periodic Table
• Type II
– Metals that can have more than one
possible charge
– Determine metal cation’s charge from the
charge on anion
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Type I Binary Ionic Compounds
• Contain Metal Cation + Nonmetal Anion
• Metal listed first in formula & name
¶ Name metal cation first, name nonmetal
anion second
¶ Simple metal cation name is the metal
name
– simple metals are Groups 1A, 2A and Al, Ga &
In
¶ Nonmetal anion named by changing the
ending on the nonmetal name to -ide
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Type II Binary Ionic Compounds
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Contain Metal Cation + Nonmetal Anion
Metal listed first in formula & name
¶ Name metal cation first, name nonmetal anion
second
¶ Metal cation name is the metal name followed by
a Roman Numeral in parentheses to indicate its
charge
– Determine charge from anion charge
– Common Type II cations in Table 5.2
¶ Nonmetal anion named by changing the ending
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on the nonmetal name to -ide
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Determining the Charge on a Cation –
Au2S3
 Determine the charge on the anion
Au2S3 - the anion is S, since it is in Group 6A, its
charge is -2
 Determine the total negative charge
since there are 3 S in the formula, the total
negative charge is -6
 Determine the total positive charge
since the total negative charge is -6, the total
positive charge is +6
 Divide by the number of cations
since there are 2 Au in the formula & the total
positive charge is +6, each Au has a +3 charge
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Type III - Binary Compounds of 2
Nonmetals
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Name first element in formula first, use the full
name of the element
Name the second element in the formula as if it
were an anion
– However, remember these compounds do not contain
ions!
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Use a prefix in front of each name to indicate the
number of atoms
Never use the prefix mono- on the first element
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Prefixes
Subscript
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Prefix
mono(not used on first nonmetal)
ditritetrapentahexaheptaocta-
• Drop last “a” in the prefix if the name begins with
vowel
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Compounds Containing
Polyatomic Ions
• Polyatomic ions are charged entities that
contain more than one atom
– Must memorize name, formula and charge
– Look for Patterns!!
• Polyatomic compounds contain one or more
polyatomic ions
• Name polyatomic compounds by naming
cation and anion
– Non-polyatomic ions named like Type I and II
• Polyatomic Acids contain H+ and a polyatomic
anion
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Patterns for Polyatomic Ions
 Elements in the same column on the
Periodic Table form similar polyatomic
ions
– same number of O’s and same charge
ClO3- = chlorate  BrO3- = bromate
 If the polyatomic ion starts with H, add
hydrogen- before the ions name and
add 1 to the charge
CO32- = carbonate  HCO3- = hydrogen
carbonate
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Patterns for Polyatomic Ions
• -ate ion
– chlorate = ClO3-
• -ate ion plus 1 O  same charge, per- prefix
– perchlorate = ClO4-
• -ate ion minus 1 O  same charge, -ite suffix
– chlorite = ClO2-
• -ate ion minus 2 O  same charge, hypoprefix, -ite suffix
– hypochlorite = ClO-
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Acids
• Contain H+ cation and anion
• Binary acids have H+ cation and a
nonmetal anion
• Oxyacids have H+ cation and a
polyatomic anion
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Writing the Formulas from the Names
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For Type III compounds, use the prefixes
to determine the subscripts
For Type I, Type II, polyatomic
Compounds and Acids
– Determine the ions present
– Determine the charges on the cation and
anion
– Balance the charges to get the subscripts
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