Chemical Nomenclature
Section 2.2
Nomenclature
-system used in
chemistry to name
compounds
Ionic
Compounds
Covalent
Compounds
Naming Ionic Compounds
Binary compounds and
Polyatomic compounds
Binary Compounds
Binary Compounds- are inorganic
compounds that contain
2 elements
 Write the full name of the cation (metal)
 Write the root of the anion (non-metal) next to
the cation
 Write the ending –ide next to the root of the
anion
 Ex: AlCl3 = aluminum chlorine 
Aluminum chloride
Transition Metal Ions
 Some elements may form more than one cation
(ions with different charges), these are called
multivalent ions.
 You will indicate the charge of the ion by writing
the charge in roman numerals after the cation
name
 Use the cross up rule to find charges!
Ex:
Fe2O2 and Fe2O3
______________ and ______________
Multivalent (Two Valences)
Element
Copper
Mercury
Lead
Ion
Stock System
Classical System
Cu+
Copper (I)
cuprous
Cu 2+
Copper (II)
cupric
Hg+
mercury (I)
mercurous
Hg2+
mercury (II)
mercuric
Pb2+
lead (II)
plumbous
Pb4+
lead (IV)
plumbic
Example of Multivalents
 Write the name using the classical system
and the stock system for the following:
 HgO
PbO2
 Write the chemical formula from the following
names.
 Cobaltic iodide
stannous fluoride
Polyatomic Compounds
 Polyatomic Ions-
 compounds that contains 3
elements (often called tertiary
compounds).
Polyatomic Ions you should know!
Common Polyatomics
 OH-  Hydroxide
 NO2-  Nitrite
 SO32-  Sulfite
 ClO2 -  Chlorite
Weird Polyatomics
 CN-  Cyanide
 CH3COO-  Acetate
 NH4+  Ammonium
 ClO3-  Chlorate
 CO32-  Carbonate
 NO3-  Nitrate
 SO42-  Sulfate
 PO43-  Phosphate
Page 98 Table 3.4
MORE TO KNOW 
Naming Polyatomic Ionic Compounds
 Naming a polyatomic ionic compound is a
similar process to naming a binary
compounds only the ending of the anion is
given from the chart …and does not
change!
 Examples:
 Calcium Chlorite
 Ca(ClO3)2  Calcium Chlorate
 Ca(ClO2)2
Naming
Molecular Compounds
Molecular Compounds
 Molecular compounds= 2 non-metals
 The system of naming molecular compounds
is based on the use of prefixes
Pre-fixes you need to know
 1  Mono-
 6  Hexa-
 2  Di-
 7  Hepta-
 3  Tri-
 8  Octa-
 4  Tetra-
 9  Nona-
 5  Penta-
 10  Deca-
Naming Molecular Compounds
 Prefixes are used to designate how many
atoms of each element are present.


RULES:
NOTE: The prefix mono- is not used with
the first elements name.
1. The first element is named with the
appropriate prefix
2. The second element’s root name with the
appropriate prefix and ending -ide
Examples
 Name the compound: N2O4
2 Nitrogens  Di-nitrogen
4 Oxygens  Tetra – oxy – ide
Dinitrogen Tetraoxide
 Name the compound: SO2
1 Sulfur  Sulfur
2 Oxygens  Di – oxy – ide
Sulfur Dioxide
Naming Acids
(Chapter 10)
Naming Acids: Rules
 There are 2 main kinds of acids:
1.binary acids
2. oxoacids
Binary Acids- composed of 2 elements
Hydrogen + non-metal
General Formula: HX (aq)
Examples: HF (aq) =hydrofluoric acid
HCl (aq) = hydrochloric acid
Naming Binary Acids
1)
If the name of the anion ends in “–ide”, the
acid name begins with the prefix “hydro-”,
then the stem of the anion is given and
finally the suffix “-ic” is added and is
followed by the word “acid”.
Example:
H2S (aq)
(anion: sulfide)  hydro + stem + ic + acid
Hydrosulfuric Acid
Naming Binary Acids
 Every acid formula starts with “H”, as the cation.
To name an acid, look at the anion the hydrogen is
bonded to.
Name: HCl (aq) =hydrochloric acid
Prefix + root name of non-metal + suffix + “acid”
Hydro +
chlor
+ ic + acid
 How do you know when to do this?
What about these?
 H2S
 H2SO3
 H2SO4
anion = sulfide ion
Add one
more “O”
anion = sulfite ion
anion = sulfate ion
Oxoacids- an acid formed from a polyatomic ion.
Hydrogen + Oxygen +Element
General Formula: HXOn (aq)
Examples: HClO4 (aq)
Naming Oxoacids
“ITE”  “OUS”
If the name of the anion ends in “–ite”, the
acid name is the stem of the anion with the
suffix “–ous” and is followed by the word
“acid”.
H2SO3 (aq) Stop and think about the anion SO322)
(anion: sulfite)  stem + ous + acid
Sulfurous Acid
Naming Oxoacids
“ATE”  “IC”
3)
If the name of the anion ends in “–ate”, the acid
name is the stem of the anion with the suffix “–
ic” and is followed by the word “acid”.
H2SO4 (aq) Stop and think about the anion SO42(anion: sulfate)  stem + ic + acid)
Sulfuric Acid
Adding Oxygens
Polyatomic
Ion
Prefix
Suffix +
acid
ClO-
hypo
ous acid
ClO2-
-
ous acid
ClO3-
-
ic acid
ClO4-
per
ic acid
Writing Formulas/Naming Acids
 Remember the following statements…
“I ate it and it was icky.”
-ate becomes -ic
“Rite ous” as (Righteous)
-ite becomes -ous
Naming Acids Flowchart
Does the formula
contain Oxygen?
No=Binary Acid
Yes=Oxoacid
Hydro “stem”ic acid
Anion end in __ ?
“ate”
“stem”ic acid
“ite”
“stem”ous acid
Writing Formulas for Acids
 If the name starts with “hydro”
Hydroselenic Acid
Write the hydrogen ion with charge.
H+1
Write the anion with the proper charge.
Se-2
Balance the charges using subscripts.
H2Se (aq)
Writing Formulas for Acids
 If the name contains the suffix “–ous”
Nitrous Acid
Write the hydrogen ion with charge.
H+
Look up the polyatomic ion (nitrite) and write
it with the correct charge.
NO2Balance the charges using subscripts.
HNO2
Writing Formulas for Acids
 If the name contains the suffix “–ic” without
the prefix “hydro”
Phosphoric Acid
Write the hydrogen ion with charge.
H+
Look up the polyatomic ion (phosphate) and
write it with the correct charge.
PO4-3
Balance the charges using subscripts.
H3PO4
Naming Bases
 Bases are named using the traditional ionic
naming system.
Metal name + polyatomic ion name
Examples:
Ca(OH)2 = calcium hydroxide
NaOH
= sodium hydroxide
Al(OH)3
= aluminum hydroxide
Writing Base Formulas
 Base formulas are written using the
traditional ionic system.
Look up the metal ion. Write the symbol
with the proper charge. Ca+2
Look up the polyatomic ion. With bases,
this will always be hydroxide, OH-1.
Balance the charges using subscripts.
Ca(OH)2