Nomenclature is the process of
naming chemical compounds
with different names so that
they can be easily identified as
separate chemicals.

• ionic compounds
• molecular compounds

• are compounds made of metal and nonmetal
• where the compound name has an ending of –
ide.
• Cations have positive charges while anions have
negative charges.
• The net charge of any ionic compound must be
zero which also means it must be electrically
neutral. For example, one Na+ is paired with one
Cl-; one Ca2+ is paired with two Br-

The subscript of the cation is numerically equal
to the charge on the anion, and the subscript of
the anion is numerically equal to the charge on
the cation.
Example:

Write the formula of the following ionic compounds.

Write the formula of the following ionic compounds.

BINARY - composed of two elements – a metal
and a nonmetal
There are two rules that must be followed:
• The cation (metal) is always named first
with its name unchanged
• The anion (nonmetal) is written after the
cation, modified to end in –ide

EXAMPLES
1. NaCl
2. CaO
3. Al2S3
4. MgI2
5. BaNa2
-Sodium Chloride
-Calcium Oxide
-Aluminum Sulfide
-Magnesium Iodide
-Not an ionic compound

What is the name of
this compound:
HIJKLMNO?

Write the name of the following compound.
• NaBr
• MgF2
-Sodium Bromide
- Magnesium Fluoride

Write the formula of the following compound.
•Potassium Chloride
•Aluminum Oxide
K+Cl- -> KCl
Al2
3+O3
2- -> Al2O3

What about the transition metals and using roman
numerals? How does that work? Let’s see.
FeO Notice – metal and nonmetal.
Name the first ion. Since the first ion is a
transition element, you must use a
Roman Numeral to represent the
charge.
How do you know the charge?
Deductive reasoning.
All compounds are neutral.
Oxygen has a -2 charge (group 16)
Therefore ….. Iron must have a +2
charge since there is one iron and one
oxygen. Iron gets a Roman Numeral II.
Iron (II) Oxide
Isn’t this easy
and FUN!!!

Cu2S Name the first ion. Since it is a transition
metal, you must use a Roman Numeral.
Which Roman Numeral? The Roman
Numeral is the same as the charge of the
ion.
How do you find the charge?
Deductive reasoning!
All compounds are neutral
Sulfur has a -2 charge (group 16)
There are two coppers.
Therefore each copper must have a +1
charge for all ions to be neutral
Copper (I) Sulfide

1. MnO2
2. CuCl2
3. FeI2
4. PbCl4
5. FeS
- Manganese (IV) oxide
- Copper (II) chloride
- Iron (II) iodide
- Lead (IV) chloride
- Iron (II) sulfide

So why must we use Roman Numerals with transition elements?
• The metals in groups 1, 2, and 13 have single, definite charges.
Group 1 metals have a +1 charge.
Group 2 metals have a +2 charge.
Group 13 metals have a +3 charge.
• Transition metals may have multiple charges – usually two
different positive charges.
For example, there are two copper oxide compounds:
Cu2O and CuO
We can’t just say Copper oxide. Which one
of these is Copper oxide? We must
distinguish these by using a Roman Numeral
Cu2O
Copper I oxide
Copper is +1
CuO
Copper II oxide
Copper is +2

There are three transition elements which do not require
a Roman Numeral because they have single definite
charges. These are
Zinc – Zn+2
Cadmium – Cd+2
Silver – Ag+1
You need to remember
the charges for these.
Ag2O Name the first ion.
Silver Name the second ion
changing the suffix to –ide.
oxide
ZnCl2 Name the first ion.
Name the second ion
changing the suffix to –ide.
Zinc chloride
No
Roman
Numerals
needed
for these.

Sometimes you will see the transition elements named
using common names. Transition metals named with
Roman Numerals involves stock names.
The common names use the Latin derivative of the
element’s name with a suffix of either –ous or –ic.
The –ous suffix name corresponds with the smaller
charge.
The –ic suffix name corresponds with the larger charge.
Cuprous = Copper I
Cupric = Copper II
Ferrous = Iron II
Ferric = Iron III
Plumbous = Lead II
Plumbic = Lead IV
There are many more – just be
familiar with these six common
names.

Stock name Common Name
Copper I Cuprous
Copper II Cupric
Iron II Ferrous
Iron III Ferric
Lead (II) Plumbous
Lead (IV) plumbic
In Summary

How do you write formulas for binary
ionic compounds given the name?
Two simple steps:
1.Write the symbol and charge of each ion
2.Balance the charges by providing subscripts
Magnesium chloride Write the symbol and charge of
each ion.
Mg+2 Cl-1
Balance the charges by supplying
subscripts. Subscripts tell how many
of each atom is present.
You need a second Cl-1 to balance
the charges
Cl-1
MgCl2

More examples: Iron III bromide
Write the symbol and charge of
each ion. The charge of the iron
is provided by the Roman
Numeral.
Fe+3 Br -1
Balance the charges by
supplying subscripts. The
subscripts tell how many of
each ion is needed to balance
the compound.
You’ll need three bromine ions to
balance the one iron.
Br -1
Br -1
FeBr3

Aluminum Sulfide Write the symbol and charge of each
ion.
Al+3 S-2
Balance the charges by supplying
subscripts.
In this case the charges do not
evenly divide into each other. You
must find the least common
multiple. SIX
How many aluminums are needed
to arrive at a +6 charge?
How many sulfurs are needed to
arrive at a -6 charge?
2
3
Al+3 S-2
S-2
Al2S3

Ternary Ionic Compounds. These compounds
contain at least one polyatomic ion.
What is a polyatomic ion?
Let’s look at the name to try to understand.
It is an ion – that means it has a charge.
It is polyatomic – that means it is made of more
than one atom.
Simple as that!!
Let’s look at some examples of polyatomic ions.

CO3
-2 carbonate This ion is composed of one carbon
and three oxygens and the entire
group has a charge of -2.
Polyatomic ion – Group of atoms that act as a unit and
carry a charge.
More examples:
SO4
-2 Sulfate
SO3
-2 Sulfite
ClO4
-1 Perchlorate
ClO3
-1 Chlorate
ClO2
-1 Chlorite
ClO-1 Hypochlorite
PO4
-3 Phosphate
C2H3O2
-1 Acetate
OH-1 Hydroxide
NO3
-1 Nitrate
NO2
-1 Nitrite
You need to learn these!!!
NH4
+1 Ammonium
(only positive PI)

How do you recognize Ternary Ionic Compounds?
Composed of two ions in which at least one is a
polyatomic ion.
There is only one positive polyatomic ion (NH4
+1)
Three possible types of Ternary Ionic
Compounds:
•Ammonium + negative ion (nonmetal)
•Metal (positive ion) + negative polyatomic ion
•Ammonium + negative polyatomic ion
Polyatomic Ions

How do you name Ternary Ionic Compounds?
EASY! PIECE OF CAKE! NO PROBLEM!
Name the first ion.
Name the second ion. Isn’t that simple??!!
Examples:
Na2CO3
When you look at this compound you
should recognize that this is NOT
binary. There are THREE elements
present. When you see this,
immediately look for a polyatomic ion.
Carbonate is present here.
Name the first ion.
Sodium
Name the second ion.
carbonate
Notice that you do
NOT change the
suffix – just name
the polyatomic ion

A few more examples:
Fe(OH)3 Name the first ion.
Iron Remember that iron requires a
Roman Numeral since it is a transition
element. What Roman Numeral
should be used?
The Roman Numeral comes from the
charge of the ion. How do you find the
charge of the iron?
You know two things:
•All compounds are neutral.
•You know the charge of OH (-1)
Since there are
3 OH groups,
each with a -1
charge, the
charge of the
iron must be +3
for the
compound to be
neutral
III
Name the polyatomic ion.
hydroxide

NH4Cl Name the first ion.
Ammonium Name the second ion.
chloride
Notice that since the second ion is a nonmetal that, like
binary ionic compounds, the suffix of the nonmetal
changes to –ide.
(NH4)3PO4
Name the first ion.
Name the second ion.
Ammonium phosphate
Looks like a monster, but it’s really a pussycat.

ONE more example:
Cu2SO4
Name the first ion.
Copper
You should realize that you
need a Roman Numeral
since copper is a transition
metal.
The Roman Numeral is the
same as the charge.
What is the charge?
The charge of sulfate is -2.
Since there are two coppers,
the charge of the copper
must be +1.
I sulfate
Name the second ion.

How do you write formulas for Ternary Ionic
Compounds?
Very much like writing formulas for Binary Ionic
Compounds.
Two steps:
•Write the formulas/symbols of each ion.
•Balance the charges by supplying subscripts.
•If a subscript is needed for a polyatomic ion, it
must be put in parentheses with the subscript
on the outside.
Let’s do some!!

Aluminum nitrate First, you can tell from the name
that there is a polyatomic ion
present (nitrate). All binary ionic
compounds have suffixes of –ide.
Write the formula/symbol and charge of each ion.
Al+3 NO3
-1
Balance the charges by supplying subscripts.
Since Al is +3 and NO3 is -1, you need a total of
3NO3
-1 to balance one Al+3
Since you will need a subscript of 3 for NO3
-1, you
need to put this in parentheses with the 3 outside.
Al(NO3)3

Lead (IV) acetate Write the formula/symbol and
charge of each ion.
Pb+4 C2H3O2
-1
Balance the charges by supplying
subscripts. Since Pb is +4 and
C2H3O2 is -1, you will need 4 C2H3O2
-
1 to balance 1Pb+4
Pb(C2H3O2)4
Calcium phosphate
Write the formula/symbol and
charge of each ion.
Balance the charges by supplying
subscripts. Since Ca is +2 and PO4 is
-3, you will need 3 Ca+2 to balance 2
PO4
-3
Ca+2 PO4
-3
Ca3(PO4)2

BINARY - composed of two elements – a metal
and a nonmetal
There are two rules that must be followed:
• The cation (metal) is always named first
with its name unchanged
• The anion (nonmetal) is written after the
cation, modified to end in –ide