Chemical Nomenclature
“As ideas are preserved and communicated
by means of words, it necessarily follows
that we cannot improve the language of any
science, without at the same time improving
the science itself; neither can we, on the
other hand, improve a science without
improving the language or nomenclature
which belongs to it.”
− Antoine-Laurent Lavoisier,
Elements of Chemistry (1790)
2
STOCK & IUPAC
NOMENCLATURE SYSTEMS
In 1919, Alfred Stock published a system of
naming inorganic compounds
- still used for naming ionic compounds
Alfred Stock
(1876 – 1946)
In 1921, the International Union of Pure and
Applied Chemistry (IUPAC) developed system of
chemical nomenclature for any compound
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Molecular View of
Elements and Compounds
Types of Compounds
•
•
•
•
•
•
Covalent (molecular)
Ionic
Acids
Hydrate
ionic
Coordinate
Organic
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Covalent Compounds
• Nonmetal element(s) bonded to other
nonmetal element(s)
• Elements bond by sharing electrons
– Form molecules
• Exception #1: anything with “H” in front of
formula mixed with water is an acid
• Exception #2: anything with “NH4” in front
of formula is ionic not covalent
– NH4NO3 , NH4Cl, (NH4)3N , etc are not
covalent
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O
H
H
7
Nomenclature Rules: Binary Covalent
Binary compound: composed of just two elements
1. Write the name of element that is first (left)
in a formula
- Most metallic element is usually listed first
2. Write the name of element that is second in
formula
3. Apply suffix “ide” to second name
- Minimize syllables as much as possible
4. Apply prefixes to denote subscripts
- Do not apply prefix “mono” for first element
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Prefixes
1
2
3
4
5
mono
di
tri
tetra
penta
6
7
8
9
10
hexa
hepta
octa
nona
deca
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Examples
CO2
carbon di oxygenide
oxygen
oxide
N2Cl4
di nitrogen tetra chlorinide
chlorine
chloride
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Write the name or formula for the
following compounds:
1.
2.
3.
4.
5.
6.
P3O10 triphosphorus decaoxide
nitrogen monoxide
NO
diiodine pentasulfide
I2S5
xenon tetrafluoride
XeF4
tribromine octaoxide Br3O8
dicarbon hexachloride C2Cl6
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Special Cases
NH3
CH4
ammonia
methane
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Special Cases
C2H2
C6H6
acetylene
benzene
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Ionic Compounds
• metal element bonded to nonmetal
element(s)
• Neutral compounds which are formed when
cations and anions come together in ratios
that balance the positive and negative charges
• Called salts
• Form formula units (not molecules)
– Formula unit: smallest representative unit of an
ionic compound
– Additional ions lead to formation of crystals
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NaCl Crystals
Formula unit: NaCl
15
Ionic vs. Molecular Compounds
Propane – contains
individual C3H8
molecules
Table salt – contains
an array of Na+ ions
and Cl- ions
Nomenclature Rules: Ionic Compounds
1. Write the name of the cation (metal)
-
Cation is usually listed first
Use anion as a guide to determine cation charge
Either Stock name or Latin name
2. Write the name of the anion (nonmetal(s))
-
Anion names already have special suffixes
[anion name] is still preferred
3. Do not apply prefixes to denote subscripts
cations and anions bond together until
total charge is zero
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Examples: Formula  Name
CaCl2
(NH4)3PO4
calcium di chloride
Fe2+ or Fe3+ ?
ammonium phosphate
Fe(BrO3)3
iron(III) bromate(V)
iron(III) bromate
ferric bromate
BrO31−
BrO31−
BrO31−
3−
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Examples: Name  Formula
lithium phosphide
Li1+
1+
Li
Li1+
1+
3+
2+
Li3P
P3−
3−
calcium nitride
Ca2+
2+
Ca
Ca2+
2+
6+
4+
N3−
3−
N
3−
6−
Ca3N2
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Criss-Cross Method
lithium phosphide
3−
P
1
1+
Li
3
calcium nitride
2+
Ca
3
Li3P1
3−
N
2
Ca3N2
strontium nitrite
Sr2+ NO21−
1
2
SrNO222)2
Sr(NO
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Watch Out for Hydroxide!!!
strontium hydroxide
Sr2+
1
OH1−
2
SrOH2 2
Sr(OH)
FAIL
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Write the name for the following
ionic compounds:
1. Na3N
sodium nitride
2. Sn(C2O4)2
tin(IV) oxalate
stannic oxalate
3. BaO2
barium peroxide
4. Cu3(PO3)2
copper(II) phosphite
cupric phosphite
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Write the formula for the following
ionic compounds:
1. Bismuth(V) carbonate
Bi2(CO3)5
2. Aluminum chlorate(III) Al(ClO2)3
3. Ferrous thiosulfate
FeS2O3
4. Cadmium hydroxide
Cd(OH)2
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Unusual Ions
Mercury (I) exists only as Hg22+
Mercury (II) is Hg2+
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Flow Chart
25
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Acids
• H is written 1st in a formula
A is usually a
• 2 Types of Acids
nonmetal
– Binary Acids (HxAy)
– Oxyacids (oxoacids) (HxAyOz)
• Nomenclature similar to ionic compounds
• Name depends on whether or not the acid
compound is dissolved in water (aqueous
solution)
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Oxyacids are the
most common acid
O
Cl
H
O
O
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Nomenclature Rules: Binary Acids
If in water (aqueous solution (aq)):
1. Write prefix “hydro”
2. Write the name of second element
3. Apply suffix “ic” to second name
- Minimize syllables as much as possible except
- Sulfur  Sulfuric Phosphorus  Phosphoric
4. Add “acid”
If not in water:
1. Write “hydrogen”
2. Write the name of second element
3. Apply suffix “ide” to second name
- Minimize syllables as much as possible
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Examples: Formula  Name
S
H
H2S(g)
di hydrogen sulfide
H
H2S(aq)
hydro sulfuric
sulfur acid
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Nomenclature Rules: Oxyacids
1. Write classical name of the anion
2. Change ending of anion
“ate”  “ic”
“ite”  “ous”
3. Add “acid”
HClO3(aq)
chlorateacid
chloric
HNO2(aq)
nitrite acid
nitrous
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Write the name or formula for the
following aqueous acids:
1. HBr
hydrobromic acid
2. HBrO3
bromic acid
3. hypochlorous acid
HClO
4. ethanoic acid
HC2H3O2
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Flow Chart
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