HH Chemistry
Topic F – Naming and Formulas – 06
Block 051
Ionic Names and Formulas – Part 3
Block 051:
Ionic Names and Formulas – Part 3
Page 1 of 4
NAME: ________________________________
To write the names of an ionic compound, you must first know what ions it is made of. Suppose you want
to name the following compounds:
A) Na2O
B) Sr3(PO4)2
C) FeO
D) Fe2O3
The first step in ionic naming is to break up each compound into positive and negative ions. Disregard the
number of ions of each type, instead focusing on the identity of the ions and their charges.
A) Na2O
B) Sr3(PO4)2
C) FeO
D) Fe2O3
becomes
becomes
becomes
becomes
Na1+ and O2−
Sr2+ and PO43−
Fe??? and S2−
Fe??? and S2−
It should always be possible to identify the negative ions. Oxide, O2−, and sulfide, S2−, are elemental anions,
and their charges (both are 2−) should be determined by their position in the Periodic Table. Phosphate,
PO43−, is a common ion, and should have been memorized by this point.
While the charge on the negative ions will always be simple to determine, the charge on the positive ions
will not always be easy to find. In examples A and B, it is easy to identify sodium, Na1+, and strontium, Sr2+,
as the positive ions. Sodium is in the first column of the periodic table, and always has a 1+ charge.
Strontium is in the second column of the periodic table, and always has a 2+ charge. Examples C and D
involve iron, Fe, a positive ion that does not only form one type of ion. Iron, like many other transition
metals, can make several different ions. If you recall, ions like this require Roman numerals to signify what
charges they make.
The next step in naming a compound is to name the positive ion, followed by the negative ion. If the
positive ion can have more than one possible charge, leave parentheses and space for Roman numerals in
the name.
A) Na2O
B) Sr3(PO4)2
C) FeO
D) Fe2O3
is named
is named
is named
is named
sodium oxide
strontium phosphate
iron ( ) oxide
iron ( ) oxide
HH Chemistry
Topic F – Naming and Formulas – 06
Block 051
Ionic Names and Formulas – Part 3
Page 2 of 4
Examples A and B are now completely solved. Examples C and D are another matter. To solve for
compounds that require Roman numerals, consider drawing models of the compound like the models you
made in the naming and formula writing activity.
In example C, there is one iron ion for every one oxide ion. That means each
iron ion must have a 2+ charge, to balance out the 2− charge on oxide. The
name would therefore be iron (II) oxide.
In example D, there are three oxide ions. Because oxide ions have a 2−
charge, the total negative charge is 6−. This 6− charge must be balanced out
by a 6+ charge. Since there are two iron ions, each one must have a charge of
3+, and the name of the compound would be iron (III) oxide.
Use this method whenever you have to name an ionic compound that involves a positive ion that can make
more than one charge. With enough practice, you will be able to find the name of any ionic compound.
Write the names of the following compounds.
Na3PO4
SrCO3
Fe(ClO3)2
_____________________
_____________________
_____________________
Na2SO4
SrI2
Fe(ClO3)3
_____________________
_____________________
_____________________
CaSO4
PbCO3
Fe2(Cr2O7)3
_____________________
_____________________
_____________________
Cu(CN)2
Ba(BrO3)2
KCl
_____________________
_____________________
_____________________
CuNO3
PbC2O4
(NH4)3AsO4
_____________________
_____________________
_____________________
Au2O3
Al2(CO3)3
Pb(OH)2
_____________________
_____________________
_____________________
HH Chemistry
Topic F – Naming and Formulas – 06
Block 051
Ionic Names and Formulas – Part 3
Page 3 of 4
Write the names and formulas of two polyatomic anions with names that do not end in “-ite” or “-ate.”
How does the formula for perchlorate compare to the formula for chlorate?
How does the formula for hypochlorite compare to the formula for chlorite?
Write the names of the following compounds.
NaClO3 ________________________
CaH2 ________________________
K2CrO4 ________________________
K2SO4 ________________________
Al(IO3)3 ________________________
KHSO4 ________________________
SnO2 ________________________
Pb(SO4)2 ________________________
Fe(C2H3O2)3 ________________________
NaMnO4 ________________________
Fe(C2H3O2)2 ________________________
Al(CN)3 ________________________
HH Chemistry
Topic F – Naming and Formulas – 06
Block 051
Ionic Names and Formulas – Part 3
Write formulas for the following compounds.
potassium permanganate ___________
zinc acetate ___________
calcium carbonate ___________
calcium hydrogen carbonate ___________
potassium hydroxide ___________
lead (II) fluoride ___________
strontium hydroxide ___________
lithium dichromate ___________
iron (II) chlorate ___________
iron (III) perchlorate ___________
iron (II) chlorite ___________
lead (IV) hypochlorite ___________
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