Nomenclature
Chapter 9
Chemical Formula

Chemical Formulas tell two things:
• Letters = elements
• Subscripts = # of atoms of each element
Ex. Fe2O3 2 iron atoms & 3 oxygen atoms
CaCO3  # elements?
# atoms?
3
5
Al2(SO4)3  # elements? 3
# atoms?
17
Compounds

Binary compound  has 2 elements
• Ex. NaCl

Ternary compound  has 3 elements
• NaNO3
Review of Ionic Compounds

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Attraction of (+) and (-) ions.
(transfer e-)
Metal loses e-  (+)
Nonmetal gains e-  (-)
Cation (metal) is written FIRST!!
The OVERALL charge of the
compound is ZERO.
Binary Ionic Names


How do you know it’s binary ionic?
• metal + nonmetal
Rules:
1) Name the first element as it is on
the periodic table.
2) Change the ending of the second
element to “ide”.
3) Check if the metal is a transition
metal. If so, figure out the charge on
it and use Roman numerals to show the
CHARGE.
Binary Ionic Naming Examples

NaBr  sodium bromide

CaCl2  calcium chloride

Cu2O  copper (I) oxide

Fe2O3  iron (III) oxide

K2S 

Sr3P2  strontium phosphide

CoBr  cobalt (I) bromide

Mn3N  manganese (I) nitride
potassium sulfide
Binary Ionic Naming Exceptions


Lead (Pb) and Tin (Sn) are not
transition metals, but THEY DO NEED
ROMAN NUMERALS!!
Silver (Ag) and Zinc (Zn) are
transition metals, but DO NOT NEED
ROMAN NUMERALS!
• Sliver is ALWAYS +1
• Zinc is ALWAYS +2
Binary Ionic Formulas

Rules:
1) Write the element symbols.
2) Write the oxidation #s (charges).
* If it’s a transition metal, you won’t know
the charge – so look at the Roman
numeral!
3) Criss-cross the charges down.
4) Simplify the ratio if needed.
Binary Ionic Formula Examples

Write the formula for each name:
• copper (II) oxide
CuO
• zinc bromide
ZnBr2
• copper (I) oxide
Cu2O
• barium chloride
BaCl2
• lead (IV) sulfide
PbS2
• calcium nitride
Ca3N2
• iron (III) sulfide
Fe2S3
• aluminum fluoride
AlF3
• silver oxide
Ag2O
Ternary Ionic Compounds

Involve polyatomic ions (group of atoms
with an overall charge)

Most polyatomic ions have “ite” or “ate”,
meaning oxygen is in it.

Treat the polyatomic ion as a unit and
never change its name!! (Don’t use “ide”
for it.)

Put polyatomic ions in parentheses unless
the subscript is 1.

NEVER change the subscripts within the
polyatomic ion!!
Naming Ternary Ionic Compounds
1) Name the (+) ion.
2) Name the (-) ion (no “ide” if it’s a
polyatomic ion!).
3) Use Roman numerals if the metal is
a transition metal, lead or tin.
Name Ternary Ionic Examples

BaSO4
barium sulfate

NH4OH
ammonium hydroxide
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Cu(NO3)2 copper (II) nitrate
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Fe2(CO3)3 iron (III) carbonate
KNO3
potassium nitrate
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Co(OH)2

cobalt (II) hydroxide
Writing Formulas for Ternary Ionic
Compounds
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Use the same criss-cross method as
with binary compounds.
Remember to use ( ) if the subscript
of a polyatomic ion is more than 1!
(Watch out for hydroxide!)
Ternary Ionic Formula Examples

Write the formula for each:
• aluminum sulfate
Al2(SO4)3
• ammonium carbonate (NH4)2CO3
• tin (IV) phosphate
Sn3(PO4)4
• sodium nitrite
NaNO2
• zinc hydroxide
Zn(OH)2
• potassium sulfite
K2SO3
Molecular Compounds

Review of Molecular Compounds:
• Involves a sharing of e• Molecules can exist independently
• Covalently bonded

How do you know it’s molecular?
• All nonmetals!
Naming Molecular Compounds

Use prefixes to indicate the number of
atoms.
• 1 Exception: Do NOT begin a name with
“mono”.

Change the ending of the second element
to “ide”.
mono
1
hexa
6
di
2
hepta
7
tri
3
octa
8
tetra
4
nona
9
penta
5
deca
10
Naming Molecular Compounds Examples

CO
carbon monoxide

CO2
carbon dioxide
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P2O5
diphosphorous pentoxide
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P4O10
tetraphosphorous decoxide
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N2O
dinitrogen monoxide
Molecular Formulas
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The prefix tells you what subscript to
write.
Remember if there is no prefix for
the first element, it is “mono”.
Molecular Formula Examples

dinitrogen monoxide
N2O

sulfur trioxide
SO3

dinitrogen pentoxide
N2O5

nitrogen trihydride
NH3

pentaphosphorous decoxide
P5O10
When you look at a compound:
First – Decided if it’s ionic or molecular!!
* Ionic
m – nm
polyatomic ions
* Molecular
nm - nm
Acids

What is an acid?
• An aqueous solution (in water) of
hydrogen compounds

How do you know something is an
acid?
• It starts with H
Binary Acids


Binary acid  Includes H + one other
element. (Ex. HBr)
To name: “hydro
ic acid”
Naming Binary Acid Examples

Examples:
• HCl
• HBr
• H2S
hydrochloric acid
hydrobromic acid
hydrosulfuric acid
Binary Acid Formulas

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Don’t forget to use the criss-cross
method!
Examples:
• hydroiodic acid
• hydrofluoric acid
• hydrophosphoric acid
HI
HF
H3P
Ternary Acids

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Ternary acid  H + polyatomic ion.
(Ex. HNO3)
If the polyatomic ion’s name ends in “ate”,
the acid’s name ends in “ic”.
(I “ate” it and it made me s”ic”k.)
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If the polyatomic ion’s name ends in “ite”,
the acid’s name ends in “ous”.
Naming Ternary Acids
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phosphoric acid
sulfurous acid
sulfuric acid
H2CO3
HNO2
HNO3
H3PO4
H2SO3
H2SO4
carbonic acid
nitrous acid
nitric acid
MEMORIZE THESE!!
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Hydrochloric acid – HCl
Nitric acid – HNO3
Sulfuric acid – H2SO4
Acetic acid – HC2H3O2 or CH3COOH