Chapter 8.
Chemical Nomenclature
Chemical nomenclature is the system
of names used to distinguish chemical
compounds from each other, and the
rules needed to devise these names.
Chemical Nomenclature
Why Bother?
How do you speak Al2(SO4)3 ?
What system do we use?
IUPAC International Union of Pure
and Applied Chemistry
Chemical Nomenclature
Three major categories of compounds:
Ionic
First element in formula is a metal.
Molecular
First element in formula is a nonmetal.
Acid
First element in formula is Hydrogen.
Naming Ionic Compounds
Types of ionic compounds:
Binary, contains two elements:
NaCl, MgBr2, Fe2O3
Ternary, contains three elements;
two are in a polyatomic anion:
NaNO3, NH4Cl, Cr2(SO4)3
Naming Binary Ionic Compounds
What is the charge on the metal ion?
Fixed: Group 1A, +1; Group 2A, +2
Al3+, Ga3+, Zn2+, Cd2+, Ag1+
Examples:
NaCl, Al2O3, CdS
Name cation as element, e.g. sodium
Name anion with stem of element name,
followed by suffix ide, e.g. chloride
Naming Binary Ionic Compounds
What is the charge on the metal ion?
Variable: All other metals
Examples: CuO, FeBr2, Fe2O3
Name cation as element, followed by charge
in Roman numerals, enclosed by
parentheses, e.g. copper(II)
Name anion with stem of element name,
followed by suffix ide, e.g. oxide
Naming Binary Ionic Compounds
What is the charge on the metal ion?
The compound must be electrically neutral.
Use the charge on the anion to figure out
the charge on the metal.
Examples:
FeO, Fe2O3
CuCl, CuCl2
SnF2, SnF4
Hg2Cl2, HgCl2
Naming Binary Ionic Compounds
An older naming system gives the suffix ic to
the ion with the higher charge, and the suffix ous to the ion with the lower charge,
following the (usually Latin) element stem.
FeO ferrous oxide;
CuCl cuprous chloride
SnF2 stannous fluoride
Hg2Cl2 mercurous chloride
Fe2O3 ferric oxide
CuCl2 cupric chloride
SnF4 stannic fluoride
HgCl2 mercuric chloride
Naming Ternary Ionic Compounds
Name metal as you would for a binary, with
charge if necessary.
Name anion as itself. Know these:
CO32NO31PO43SO42OH1-
carbonate
nitrate
phosphate
sulfate
hydroxide
ClO1- hypochlorite
ClO31- chlorate
C2H3O21- acetate
CH3COO1- acetate
CN1- cyanide
Naming Ternary Ionic Compounds
There is one polyatomic cation
NH41+, ammonium
Name it, then name anion properly
Formulas from Names
Write symbol for metal ion first, then anion.
Use the charges on the ions to determine
how many of each ion are present in the
formula. Charges must sum to zero.
If a polyatomic ion appears more than once
in a formula, enclose it in parentheses,
followed by a subscript showing the
number of times the ion occurs in the
compound.
Practice
Give Name
CaCl2
Mg(NO3)2
Al2(SO4)3
FeCl3
AgBr
MnO2
NH4NO3
Give Formula
Mercurous iodide
Mercury(II) iodide
Silver nitrate
Ammonium bromide
Tin(II) hydroxide
Sodium cyanide
Calcium phosphate
Naming Molecular Compounds
These are all binary. Since the atoms do not
have charges, use Greek numerical prefixes to indicate the number of each atom in
the molecule.
Know these:
1
mono
2
di
3
tri
4 tetra
5 penta
6 hexa
Naming Molecular Compounds
How to name them:
1. Prefix for first element in formula,
omit if it's "mono"
2. Name first element
2. Prefix for second element in formula,
3. Give stem of second element followed
by suffix ide.
CO Carbon monoxide
CO2 Carbon dioxide
N2O Dinitrogen monoxide
Naming Molecular Compounds
Details and exceptions:
If last letter of prefix for number and first
letter of element are both vowels, drop the
last letter of the prefix:
CO
carbon monoxide
N2O5 dinitrogen pentoxide
Some compounds are known only by
common names.
H2O water
NH3 ammonia
Formulas from Names
Write symbol for least electronegative
element first, then most electronegative.
Use prefixes to determine subscripts in
formula.
Metalloids are not metals, and their compounds are named as molecular compounds.
Practice
Give Name
NO2
SO3
SiO2
TiO2
NO
P2O5
Fe2O3
Give Formula
Carbon tetrachloride
Phosphorus trichloride
Selenium dibromide
Dinitrogen tetroxide
Sulfur dioxide
Xenon tetrafluoride
Diantimony Trioxide
Naming Acids
Types of acids:
Binary, contains two elements:
HCl, HBr, H2S
Ternary, contains three elements;
two are in a polyatomic ion:
HNO3, H2SO4, H3PO4
Naming Binary Acids
Binary acids are gases as pure compounds.
Symbol: HCl or HCl (g)
Name:
hydrogen + stem of nonmetal
followed by suffix -ide.
hydrogen chloride
Naming Binary Acids
The compounds become acidic in water
solution (aqueous solution); they ionize.
HCl + H2O  H3O1+ + Cl1-
H3O1+ is what makes acids acidic.
Symbol:
HCl (aq)
Name:
prefix hydro- + stem of nonmetal
followed by suffix -ic acid.
hydrochloric acid
Naming Ternary Acids
No distinction is made between pure ternary
acids and those in aqueous (water) solution.
Symbol:
H2SO4
Name:
stem of central atom followed
by suffix -ic acid.
sulfuric acid
Naming Ternary Acids
Know names of these ternary acids. They are
related to "must know" polyatomic anions:
H2CO3
HNO3
H3PO4
H2SO4
HOH
HClO
HClO3
HC2H3O2
CH3COOH
HCN (aq)
Naming Acids and Anions
Useful Generalization:
If the name of an anion ends in -ide,
its aqueous acid is named as
hydrostemic acid.
If the name of an anion ends in -ate,
its acid is named as stemic acid.
Practice
Give Name
HBr (aq)
HNO3
H 2O
H 2S
HF
H3PO4
HI (aq)
Give Formula
Sulfuric acid
Carbonic acid
Hydrogen iodide
Hypochlorous acid
Hydrocyanic acid
Acetic acid
Chloric acid
Naming Mixed Salts
Mixed salts are compounds in which Na1+
or K1+ combine with H1+ and an anion
with -2 or -3 charge.
Symbol:
KHSO4
Name:
metal cation, hydrogen, anion
Potassium hydrogen sulfate
Naming Mixed Salts
If the anion has -3 charge (PO43-), three cations
are required to form a neutral compound.
Symbol:
NaH2PO4
Name:
metal cation, prefix di-hydrogen, anion
Sodium dihydrogen phosphate
Symbol:
K2HPO4
Name:
prefix di-metal cation, hydrogen, anion
Dipotassium hydrogen phosphate
More Practice
Give Name
AgNO3
CaS
NH3
NaHS
ZrO2
H2SO4
Al2O3
Give Formula
Magnesium sulfate
Ferric chloride
Nitric acid
Lead(IV) sulfate
Sodium hydrogen carbonate
Mercuric bromide
Phosphorus trifluoride