Nomenclature
Chapter 9
Types of Ions
Monatomic – contains only one atom
Examples: Na+, FCharge is equal to oxidation number, which is the
number of electrons transferred.
Polyatomic – contains more than one atom
Examples: NH4+, OHIf the anions contain at least one oxygen then they
are called oxyanions.
Oxyanions
In general there are two types of oxyanions
formed about the same second atom.
The ion with one more oxygen is always named
with the suffix –ate. Sulfate – SO42The ion with one less oxygen is always named
with the suffix –ite. Sulfite – SO32-
Chemical Formula
When writing a chemical formula for an ionic
compound, one always writes the chemical
symbol for the cation first and the chemical
symbol for the anion second.
You place a subscript number to the lower right
to represent the number of each ion in the
formula.
Al2O3
For only one ion you place no number. NaCl
Types of Compounds to Name
1. Type I – Ionic compound from the representative
elements (only A groups) - (Metal-Nonmetal)
2. Type II – Ionic compound where the cation is a
transition metal (d-block) - (Metal-Nonmetal)
Exceptions: Ag+, Zn2+, Cd2+ (Type I)
Pb and Sn (Type II)
3. Type III – Molecular compound (all Nonmetals)
4. Type IV – Acids (Formula begins with H, Name ends
with Acid)
Type I Naming
Binary:
Write the name of the metal cation followed by
the changed suffix of the anion to –ide.
Example: NaCl – Sodium Chloride
Ternary:
Write the name of the metal/polyatomic cation
followed by the name of the element/polyatomic
anion from the back of the periodic table.
Example: Mg(OH)2 – Magnesium Hydroxide
Type I Formulas
Binary:
Find the two elements named and identify their
charges.
If equal, write the two element symbols cationanion. Calcium Oxide - CaO
If unequal, write the symbols and swap the
charges to subscripts leaving out any 1s.
Aluminum Fluoride – AlF3
Type I Formulas
Ternary:
Find the metal/polyatomic cation and the
element/polyatomic anion and identify their
charges.
If equal write the symbols cation-anion.
Potassium Nitrate - KNO3
If unequal write the symbols and swap the
charges to subscripts leaving out any 1s and
placing parentheses around any polyatomic with
a subscript >1. Barium Cyanide – Ba(CN)2
Type II Naming
Both Binary and Ternary: Transition Metal Cation
Look up anion and charge then calculate charge
of transition metal. Cation = Anion
Write transition metal name followed by the
charge in parentheses as a roman numeral and
then the name of the anion.
NiBr2 – Nickel (II) Bromide
FePO4 – Iron (III) Phosphate
Type II Formulas
Both Binary and Ternary: Transition Metal Cation
The roman numeral is the charge of the
transition metal cation, look up the anion charge
If equal write the symbols cation-anion.
Copper (I) Fluoride – CuF
If unequal write the symbols and swap the
charges to subscripts leaving out any 1s and
placing parentheses around any polyatomic with
a subscript >1. Gold (II) Nitrite – Au(NO2)2
Type III Naming
Uses prefixes to tell you how many of each element are in
the compound.
The prefixes are Mono, Di, Tri, Tetra, Penta, Hexa, Hepta,
Octa, Nona, and Deca.
Write the first element like you would a metal in Type I
including any prefix other than Mono.
Then write the second element the same way you would
in Type I including any prefix.
CO2 – Carbon Dioxide
N2O – Dinitrogen Monoxide
SF6 – Sulfur Hexafluoride
Type III Formulas
From the prefixes write the elements with their
appropriate subscripts.
Carbon Monoxide - CO
Dinitrogen Pentaoxide – N2O5
Phosphorous Trichloride – PCl3
Type IV Naming
Binary Acids – Contain no Oxygen
Start with HydroChange the anion suffix to –ic
Add the word Acid
HBr is Hydrobromic Acid
HCN is Hydrocyanic Acid
Exceptions: NH3 is Ammonia and H2O is Water
Type IV Naming
Ternary/Oxy acids: Contain Oxygen
Start with the name of the base anion, but
change the –ate suffix to –ic, add Acid or
change the –ite suffix to –ous, add Acid
HNO3 – Nitric Acid
H2SO3 – Sulfurous Acid
Type IV Formulas
Binary Acids – Contain no Oxygen
Find the symbol and the charge for the anion,
add Hydrogens to equal the charge.
Hydrosulfuric Acid - S2- - H2S
Ternary Acids – Contains Oxygen
Find the polyatomic anion and its charge, add
Hydrogens to equal the charge.