Naming Ionic Compounds
Ionic Compounds in water
Water’s formula is
H2O.
 Take a look at pg
189

Ionic Compounds
 Positive
Ion is called a
CATION. They are metals.
 Negative
Ion is called an
ANION. They are nonmetals.
Ionic Compounds
Notice the cross
over of Charges
 The Cation is
always written
FIRST, Anion
Second.
 Ionic compounds
are made up of
metals and nonmetals, the metal
is written FIRST.

Formation of Ionic Compounds
Crossing Rule
+2
-1
Ca + Cl
CaCl2
Naming Rules
Step 1: The name of the metal is written
first, the same way it is written on the
periodic table
 Step 2: Write the name of non-metal
second, BUT change the ending of the
element to –ide.
 Step 3: Remember the crossing rule and
remember to reduce!

Example
+2
-1
Ca + Cl
Calcium + Chlorine => ide
Chloride
Note: Oxygen becomes oxide
CaCl2
Calcium
Chloride
Multiple Ionic Charges & Names

Some Transition metals can have more than one
charge and therefore more than one name.
Element name
Symbol Ionic
Charges
Roman
numeral
Copper
Cu
+1, +2
I, II
Iron
Fe
+2, +3
II, III
Lead
Pb
+2, +4
II, IV
Tin
Sn
+2, +4
II, IV
When writing the names
Write the name of the element followed
by the Roman numeral.
 EX: Cu2+ is written
Copper(II)
 So, what is the name of Fe3+ ?
 How would you write the name of
PbCl4?

Polyatomic Compounds
What is a polyatomic ion?
 Polyatomic
ions: groups of
atoms that tend to stay
together and carry an overall
ionic charge. See pg 196-197
Table of Common Polyatomic Ions
Name of polyatomic
ion
Ion fomula
Ionic Charge
Nitrate
NO3OHHCO3-
-1
ClO3-
-1
-2
-2
-3
+1
Hydroxide
Bicarbonate (hydrogen
carbonate)
Chlorate
Carbonate
Sulfate
Phosphate
Ammonium
CO3-2
SO4-2
PO4-3
NH4+
-1
-1
Polyatomic Compound Formulas

Formulas for polyatomic compounds is
determined the same way as ionic
compounds. Cation first, Anion second,
cross over rule
Al+3 + CO3-2
Al2(CO3)
Naming Polyatomic Compounds

Step 1: Write the name of the metal first.

Step 2: Write the name of the polyatomic
ion second.

Step 3: Smile, you’re done!