Chemical
Nomenclature
Learning Targets
•Write name & write
symbol of selected
elements
•Write name & write
formula of a variety of
compounds.
Naming Inquiry
Formula
 NaCl
 KI
 MgCl2
Name
Sodium Chloride
Potassium Iodide
Magnesium Chloride
What is a binary compound?
Naming Inquiry
Formula
Name
 NaCl
Sodium Chloride
 KI
Potassium Iodide
 MgCl2
Magnesium Chloride
What does the chemical
formula of each indicate?
Naming Inquiry
Formula
Name
 NaCl
Sodium Chloride
 KI
Potassium Iodide
 MgCl2
Magnesium chloride
Why are there two chlorines for
one magnesium?
Naming Inquiry
Formula
 NaCl
 KI
 MgCl2
Name
Sodium Chloride
Potassium Iodide
Magnesium Chloride
What are some naming rules
that can be discovered
from these examples?
I.
Elements (periodic table)
A. Symbols: come from the first
letter, or first two letters of the
element’s name.
1. First letter is always UPPERCASE,
second letter always lower case.
a. Co, cobalt
vs.
b. No, nobelium vs.
CO, carbon monoxide
NO, nitrogen oxide
2. Some use latin name for symbol, ex. Gold
(latin name = aurum or Au)
NOTES
II.
Formula: Represents composition
of a compound
A. Tells proportions of elements in
a compound relative to each
other.
1.
2.
Subscripts are used to indicate number
of atoms of each element in a compound.
(ALWAYS Whole numbers!!)
The subscript follows the atom or atoms
it refers to. If subscript follows “( )” then
everything inside the “( )” is multiplied
by the subscript.

Examples:
CO2
One atom of C, 2 atoms of O
H2 O
2 atoms of H, one atom of O
Fe3(PO4)2
3 atoms of Fe, 2 atoms of P &
8atoms of O
Formulas, continued
B. All atoms have oxidation numbers
(valence charge). This is the combining
power of the atom.
ex : Everything in Group 1 has a
+1 charge. Group 17 has -1
charge
Na +1
Cl -1 combined = 0
** You want your valences to always = 0
Examples continued
What happens when it doesn’t = 0?
Mg+2
Cl-1 = 0
You add another Cl-1
-2
so… it now looks like this:
MgCl2
Now the “combined power” is 0

You Try
Ca+2
N-3
K+
P-3
Al+3
O-2
C. Polyatomic ions or “radicals” are
groups of atoms that behave as if
they are single atoms. They also
have oxidation numbers. Examples:
SO4-2 (sulfate ion), NO3-1 (nitrate
ion)
D. We will use the concept of valence to
write formulas
1. Valence is either “+” or “-”
2. In ALL compounds, the sum of the
valences adds up to zero.
3. Metals are always “+”
4. Non-metals can be “+” or “-”
5. Most radicals are “-”, only common
“+” radical is NH4+1 (ammonium)
Application
1. Example 1: Lithium Chloride …Li 1+
and Cl 1-, so the formula must be
LiCl.
2. Example 2: Calcium Oxide …Ca 2+
and O 2-, so the formula must be CaO
3. Example 3: What about Lithium
Oxide?
4. Answer: you need two lithium atoms
for every one oxygen to
balance…Li2O
E. Atoms that have a constant
valence:
1. (+1) = first column and Ag,
2. (+2) = 2nd column plus Zn and Cd
3. (+3) Al. (See columns already
marked on your periodic table.)
(H can be -1 in some special cases)
III. Naming Binary Salts & Writing their
Formulas
A. Metal plus a non-metal (two elements).
B. Named by adding the name of the first
element (metal) to the second element
(non-metal) whose name is modified to
end in “ide.”
1. Examples:
•
•
•
•
oxygen becomes “oxide”
chlorine becomes “chloride”
sulfur becomes “sulfide”
etc…
Now… The Rules

•
Rule #1: ends in “ide” = Binary salt
NaCl
Sodium chloride
Al2O3
Aluminum oxide
KI
Potassium iodide
Rule #2: valences must = 0
C. Most metals have a variable valence and this
must be indicated in the name of the
compound.
1. The Stock System: The valence (+) of the
metal is given as a Roman numeral.
2. How does the Stock System Work?
How does the Stock System
Work?
For metals in Groups 3-16
 Iron (II) chloride
 The (II) tells me the valence of Fe.
 I know that each Cl has a -1 charge.
I have 2 Cl’s for a total charge of -2,
so the Fe has to be +2 to make the
valences add up to zero
 FeCl3 what is the oxidation of Fe?
 Iron (III) chloride, Fe+3

You Try 



Write the name or the formula using the
Stock System
CuCl
– Copper (I) chloride
CrO3
– Chromium (VI) oxide
Tin (IV) oxide
– SnO2**if you have subscripts that can be reduced… DO IT!!
– Nickel (II) oxide
– NiO
IV.Salts with Radicals
(polyatomic ions)
A.Four ways to identify salts
1. Metal + non-metal (binary)
2. Metal + Radical
3. Radical + Non-metal
4. Radical + Radical
IV.Salts with Radicals (polyatomic
ions)
Rule #3:
B. Naming Salts (other than
binary)
1. Name of metal + name of
radical
2. Name of radical + name of
non-metal (still ends in “ide”)
or radical
IV.Salts with Radicals (polyatomic
ions)
C.The “common-form” of the
radical MUST BE MEMORIZED
1. “common form” = “ate”
ending
a. Make Flash-Cards!!!!!
2. Other endings are based on
“ate” ending
You Try: Write formula or name
Calcium phosphate
= Ca3(PO4)2
Ca+2 PO4-3
Potassium acetate
+1
-1
K
C2H3O2
= KC2H3O2
NaOH
= Sodium hydroxide
Al2(CO3)3 = Aluminum carbonate
IV. Salts with Radicals (polyatomic ions)
3. More Rules:
Rule #4: if there is one less
oxygen, then name ends in “ite”
Rule #5: If there are 2 less
oxygens the name starts with
“hypo” & ends in “ite”
Rule #6: I more oxygen then
common form starts with “per”
and ends in “ate”
 4.
Examples: NaNO3, NaNO2,
NaNO, and NaNO4
Naming compounds w/Radicals:
One more Oxygen:
 Common Form:
 One less Oxygen:
 2 less Oxygen:


4. Examples: NaNO3, NaNO2, NaNO, and
NaNO4
Naming compounds w/Radicals:
One more Oxygen: NaNO4 – Sodium pernitrate
 Common Form:
NaNO3 – Sodium nitrate
 One less Oxygen:
NaNO2 – Sodium nitrite
 2 less Oxygen:
NaNO – Sodium hyponitrite
So… what is the difference?

http://www.edinformatics.com/interactive_molecules/nitrite_and_nitrate_molecules.htm
You Try
Na2SO5
– Sodium persulfate
 Ca3(PO2)2
– Calcium hypophosphite
 Magnesium hypoflourite
– Mg(FO)2
 Iron (II) nitrite
– Fe(NO2)2

V. Naming Acids (Yep…More Rules!! )
1. Binary Acids: all have H as first element
and are aqueous  dissolved in water.
2. Can be named as common salts if not
dissolved in water.
hydrogen + non-metal.
Rule #7 - Named by:
a. Change hydrogen  hydro
b. Change non-metal -ide  -ic.
c. Followed by the word acid.
d. Example: HCl (aq) is Hydrochloric acid
You Try…

What would these be?
– HF (aq)
– Hydrofluoric Acid
– HBr (aq)
– Hydrobromic Acid
(Most are from Group 17)
H2S (aq)
 hydrosulfuric acid

3. Ternary Acids: hydrogen + radical.
a. Rule #8: Named for the radical. “ate”
ending changes to “ic” & is followed by
“acid”
1. Ex: HNO3 (aq) = Nitric Acid
b. Rule #9: “ite” ending (Rule #4) changes
to “ous”
• Ex: HNO2(aq)
Common form = NO3-1 “nitrate”
one less O, nitrous acid
c. Also uses “hypo” “ous” & “per” “ic”
You Try – Ternary Acids
Name
Formula
# of Oxygens
+1
Perchloric acid
HClO4 (aq)
Chloric acid
HClO3 (aq)
Chlorous acid
HClO2 (aq)
-1
HClO (aq)
-2
Hypochlorous acid
Common form
REVIEW…so far
Binary Salts
 Ternary Salts
 Ternary Salts
– Different # of O
 Binary Acids
 Ternary Acids
 Ternary Acids
– Different # of O

How do you
recognize…what
are the clues?
VI. Molecular Compounds
A. Greek System of naming
1. Only used for 2 non-metals
2. Ends in “ide”
3. Number of each kind of atom
is indicated by a Greek
numerical prefix (list on next
slide)
Greek prefixes used for
molecular compounds.
Mono = 1
Hexa = 6
Di = 2
Hepta = 7
Tri = 3
Octa = 8
Tetra=4
Nona = 9
Penta=5
Deca = 10
Examples
CO2
 Carbon dioxide
 You Try: P2O5, N2O4, PCl3, Chlorine
heptoxide
– Diphosphorous pentoxide
– Dinitrogen tetroxide
– Phosphorous trichloride
– ClO7

Can you fill in the blanks?
Formula
Name
CO2
N2O 5
N2O 4
_____
Carbon Dioxide
______________
_______________
Phosphorous
Trichloride
_______________
P4O10
A few more rules for naming binary compounds
of non-metals:
Rule #10: The prefix mono- is usually
omitted except where it is used for
emphasis, as in carbon monoxide.
Rule #11: Common usage omits the double
vowel – as in the example above carbon
monoxide is not carbon mono-oxide.
FYI: Some names for compounds don’t fit
the rules (ex: H2O = water NH3 = ammonia)