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Nomenclature
Naming compounds
 Writing Formulas

Naming Compounds

Binary Compounds

Compounds that contain two elements
• Name the first element
• Name the second element using an “ide”
ending
• Check the oxidation number of the first
element
• If it has more than one positive value, use a
Roman numeral to indicate the number that
was used
CaCl2
Calcium
 Calcium chloride
 Ca is +2 only


No Roman numeral needed
Calcium chloride
CCl4
Carbon
 Carbon chloride
 C is -4, +2 and +4


Since there are two positive choices,
use a Roman numeral
+4
-4
+4
-1
=0
C Cl4
Carbon IV chloride
Naming Compounds

Ternary Compounds
 Compounds that contain more than two elements
• Polyatomic ion is present
• Two or more elements that join together and act like one
substance
• Found on Table E




Identify the polyatomic used
Name the first substance
Name the second substance
Check the oxidation number of the first element
• If it has more than one positive value, use a Roman
numeral to indicate the number that was used
K2SO4
Potassium
 Potassium sulfate
 Potassium is +1 only


No Roman numeral is needed
Potassium sulfate
Cu(NO3) 2
Copper
 Copper nitrate
 Copper can be +1 or +2


Needs a Roman numeral
+2
-2
+2
-1
=0
Cu (NO3)2
Copper II nitrate
NH4Cl
Ammonium
 Ammonium chloride
 Ammonium ion is +1


No choice means no Roman numeral
needed
Ammonium chloride
Prefix System
Use a prefix INSTEAD OF a Roman numeral
 Mono


2 elements
Tri


only used for the 2nd element
Di


1
3 elements
Tetra

4 elements
CO2
Carbon dioxide
Suffix System
Used INSTEAD OF a Roman numeral
 “-ic


Highest oxidation state
“-ous”

Lowest positive oxidation state
NiCl2
Nickel II chloride
Nickelous chloride
B. Writing Formulas

Use ending to tell if compound is binary or
ternary

Binary usually ends in “ide”
•



Ternary usually ends in “ate” or “ite”
Write the symbols
Assign oxidation numbers


[except hydroxide and cyanide]
Positive atom on left, negative on right
Reduce if possible and “criss-cross”

These numbers become the subscripts of
the formula
Strontium phosphide
“ide” means binary
 Strontium (Sr)
 Phosphide is phosphorus (P)
 Sr+2 P-3

Sr3P2
Iron II Oxide




“ide” means binary
Iron (Fe)
Oxide is oxygen (O)
Fe+2 O-2
Fe2O2
reduce
FeO
Manganese IV Carbonate



“ate” means ternary
Manganese (Mn)
Carbonate is a polyatomic ion


(CO3-2)
Mn+4 CO3-2
Mn2(CO3 )4
reduce
Mn (CO3 )2
Ferrous sulfide

ferr

-ous


represents lowest positive state
sulfide


represents Fe (iron)
represents sulfur
Fe+2 S-2

Fe2S2 reduces to
• FeS
Diphosphorus trioxide
NO CHARGES ASSIGNED
NO CRISS-CROSSING
Diphosphorus
P2
Trioxide
O3
Formula
P2O3