Transcript Chemical Nomenclature
Chapter 8.
Chemical Nomenclature
Chemical nomenclature
is the system of names used to distinguish chemical compounds from each other, and the rules needed to devise these names.
Chemical Nomenclature
Why Bother?
How do you speak Al
2
(SO
4
)
3
?
What system do we use?
IUPAC
International Union of Pure and Applied Chemistry
Chemical Nomenclature
Three major categories of compounds:
Ionic
First element in formula is a metal.
Molecular
First element in formula is a nonmetal.
Acid
First element in formula is Hydrogen.
Naming Ionic Compounds
Types of ionic compounds:
Binary
, contains two elements: NaCl, MgBr
2
, Fe
2
O
3 Ternary
, contains three elements; two are in a polyatomic anion: NaNO
3
, NH
4
Cl, Cr
2
(SO
4
)
3
Naming Binary Ionic Compounds
What is the charge on the metal ion?
Fixed: Group 1A, +1; Group 2A, +2 Al
3+
, Ga
3+
, Zn
2+
, Cd
2+
, Ag
1+
Examples: NaCl, Al
2
O
3
, CdS Name cation as element, e.g. sodium Name anion with stem of element name, followed by suffix
ide,
e.g. chlor
ide
Naming Binary Ionic Compounds
What is the charge on the metal ion?
Variable: All other metals Examples: CuO, FeBr
2
, Fe
2
O
3
Name cation as element, followed by charge in Roman numerals, enclosed by parentheses, e.g. copper(II) Name anion with stem of element name, followed by suffix
ide,
e.g. ox
ide
Naming Binary Ionic Compounds
What is the charge on the metal ion?
The compound must be electrically neutral.
Use the charge on the anion to figure out the charge on the metal.
Examples: FeO, Fe
2
O
3
CuCl, CuCl
2
SnF
2
, SnF
4
Hg
2
Cl
2
, HgCl
2
Naming Binary Ionic Compounds
An older naming system gives the suffix
ic
to the ion with the higher charge, and the suf fix
ous
to the ion with the lower charge, following the (usually Latin) element stem.
FeO ferrous oxide; CuCl cuprous chloride Fe
2
O
3
CuCl
2
ferric oxide cupric chloride SnF
2
Hg
2
Cl
2
stannous fluoride SnF
4
mercurous chloride HgCl
2
stannic fluoride mercuric chloride
Naming Ternary Ionic Compounds
Name metal as you would for a binary, with charge if necessary.
Name anion as itself. Know these: CO
3 2-
NO
3 1-
PO
4 3
SO
4 2-
OH
1-
carbonate sulfate hydroxide ClO
1-
hypochlorite nitrate ClO
3 1-
chlorate phosphate C
2
H
3
O
2 1-
acetate CH
3
COO
1-
CN
1-
acetate cyanide
Naming Ternary Ionic Compounds
There is one polyatomic cation NH
4 1+
, ammonium Name it, then name anion properly
Formulas from Names
Write symbol for metal ion first, then anion.
Use the charges on the ions to determine how many of each ion are present in the formula. Charges must sum to zero.
If a polyatomic ion appears more than once in a formula, enclose it in parentheses, followed by a subscript showing the number of times the ion occurs in the compound.
Give Name CaCl
2
Mg(NO
3
)
2
Al
2
(SO
4
)
3
FeCl
3
AgBr MnO
2
NH
4
NO
3
Practice
Give Formula Mercurous iodide Mercury(II) iodide Silver nitrate Ammonium bromide Tin(II) hydroxide Sodium cyanide Calcium phosphate
Naming Molecular Compounds
These are all binary. Since the atoms do not have charges, use Greek numerical prefix es to indicate the number of each atom in the molecule.
Know these: 1 mono 2 3 di tri 4 tetra 5 penta 6 hexa
Naming Molecular Compounds
How to name them: 1. Prefix for first element in formula, omit if it's "mono" 2. Name first element 2. Prefix for second element in formula, 3. Give stem of second element followed by suffix
ide
.
CO Carbon monoxide CO
2
Carbon dioxide N
2
O Dinitrogen monoxide
Naming Molecular Compounds
Details and exceptions: If last letter of prefix for number and first letter of element are both vowels, drop the last letter of the prefix: CO N
2
O
5
carbon monoxide dinitrogen pentoxide Some compounds are known only by common names.
H
2
O water NH
3
ammonia
Formulas from Names
Write symbol for least electronegative element first, then most electronegative.
Use prefixes to determine subscripts in formula.
Metalloids are not metals, and their com pounds are named as molecular com pounds.
Give Name NO
2
SO
3
SiO
2
TiO
2
NO P
2
O
5
Fe
2
O
3
Practice
Give Formula Carbon tetrachloride Phosphorus trichloride Selenium dibromide Dinitrogen tetroxide Sulfur dioxide Xenon tetrafluoride Diantimony Trioxide
Naming Acids
Types of acids:
Binary
, contains two elements: HCl, HBr, H
2
S
Ternary
, contains three elements; two are in a polyatomic ion: HNO
3
, H
2
SO
4
, H
3
PO
4
Naming Binary Acids
Binary acids are gases as pure compounds.
Symbol: HCl or HCl (
g
) Name: hydrogen + stem of nonmetal followed by suffix -
ide
.
hydrogen chlor
ide
Naming Binary Acids
The compounds become acidic in water solution (
aqueous solution
); they ionize.
HCl + H
2
O H
3
O
1+
+ Cl
1-
H
3
O
1+
is what makes acids acidic.
Symbol: HCl (
aq
) Name: prefix
hydro-
+ stem of nonmetal followed by suffix -
ic acid
.
hydro
chlor
ic acid
Naming Ternary Acids
No distinction is made between pure ternary acids and those in
aqueous
(water) solution.
Symbol: Name: H
2
SO
4
stem of central atom followed by suffix -
ic acid
.
sulfur
ic acid
Naming Ternary Acids
Know names of these ternary acids. They are related to "must know" polyatomic anions: H
2
CO
3
HNO
3
H
3
PO
4
H
2
SO
4
HOH HClO HClO
3
HC
2
H
3
O
2
CH
3
COOH HCN (
aq
)
Naming Acids and Anions
Useful Generalization: If the name of an anion ends in
-ide
, its aqueous acid is named as
hydro
stem
ic acid
.
If the name of an anion ends in
-ate
, its acid is named as stem
ic acid
.
Give Name HBr (
aq
) HNO
3
H
2
O H
2
S HF H 3 PO 4 H I (
aq
)
Practice
Give Formula Sulfuric acid Carbonic acid Hydrogen iodide Hypochlorous acid Hydrocyanic acid Acetic acid Chloric acid
Naming Mixed Salts
Mixed salts are compounds in which Na
1+
or K
1+
combine with H
1+
and an anion with -2 or -3 charge.
Symbol: Name: KHSO
4
metal cation, hydrogen, anion Potassium hydrogen sulfate
Naming Mixed Salts
If the anion has -3 charge (PO
4 3-
), three cations are required to form a neutral compound.
Symbol: Name: Symbol: Name: NaH
2
PO
4
metal cation, prefix
di
-hydrogen, anion Sodium dihydrogen phosphate K
2
HPO
4
prefix
di
-metal cation, hydrogen, anion Dipotassium hydrogen phosphate
Give Name AgNO
3
CaS NH
3
NaHS ZrO
2
H
2
SO
4
Al 2 O 3
More Practice
Give Formula Magnesium sulfate Ferric chloride Nitric acid Lead(IV) sulfate Sodium hydrogen carbonate Mercuric bromide Phosphorus trifluoride