Chapter 5-Nomenclature
Common Names - Exceptions
• H2O = water, steam, ice
• NH3 = ammonia
• CH4 = methane
• NaCl = table salt
• C12H22O11 = table sugar
Naming Starts with Classifying Compounds
• Binary Compounds = only 2 elements
• Compounds containing polyatomic ions
• Acids = formula often starts with H
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
Binary Ionic
• Made of metal cation and
nonmetal anion
• Name by naming the ions
Metal Cations
Type I Metal Ion
• Metals that can only have one
possible charge
• Determine charge by position on
the Periodic Table
• The name of the ion is the same
as the name of the metal with no
special designations.
Type II Metal Ion
• Metals that can have more than
one possible charge
• Determine metal cation’s charge
from the charge on anion
• Metals that can have two
possible charges are identified
by adding a roman numeral to
the name of the metal. The roman numeral matches the charge of the metal ion.
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
o simple metals are Groups 1A, 2A and Al, Ga & In
 Nonmetal anion named by changing the ending on the nonmetal name to -ide
Type II Binary Ionic Compounds
 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
o Determine charge from anion charge
o Common Type II cations in Table 5.2
 Nonmetal anion named by changing the ending on the nonmetal name to -ide
Determining the Charge on a Cation – Au2S3
 Determine the charge on the anion
a. Au2S3 - the anion is S, since it is in Group 6A, its
charge is -2
 Determine the total negative charge
a. since there are 3 S in the formula, the total negative
charge is -6
 Determine the total positive charge
a. since the total negative charge is -6, the total
positive charge is +6
 Divide by the number of cations
a. since there are 2 Au in the formula & the total
positive charge is +6, each Au has a +3 charge
Type III - Binary Compounds of 2 Nonmetals (Covalent)
• 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!
• Use a prefix in front of each name to indicate the number of atoms
• Never use the prefix mono- on the first element
Compounds Containing
Polyatomic Ions
• Polyatomic ions are charged
entities that contain more than
one atom
– You do not need to
memorize these- look up
names on your ion chart!
• 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
Patterns for Polyatomic Ions
 Elements in the same column on the Periodic Table form similar polyatomic ions
o same number of O’s and same charge
o ClO3- = chlorate  BrO3- = bromate
 If the polyatomic ion starts with H, add hydrogen- before the ions name and add 1 to the charge
o CO32- = carbonate  HCO3- = hydrogen carbonate
Patterns for Polyatomic Ions- You do not need to know this- but this is good to be familiar with.
• -ate ion plus 1 O  same charge, per- prefix
– perchlorate = ClO4• -ate ion
– chlorate = ClO3• -ate ion minus 1 O  same charge, -ite suffix
– chlorite = ClO2• -ate ion minus 2 O  same charge, hypo- prefix, -ite suffix
– hypochlorite = ClOAcids
• Contain H+ cation and anion
• Binary acids have H+ cation and a nonmetal anion
• Oxyacids have H+ cation and a polyatomic anion
Writing the Formulas from the Names
• 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
Summary:
Don’t make naming more difficult that it needs to be
Decide if it is a Type I, II or III
Use the steps to name- BINARY COMPOUNDS ARE EASY!
IONS are EASY!! LOOK UP THE NAMES!