Ionic & Molecular Nomenclature
Nomenclature refers to the terminology of chemical compounds;
represents the basic “language” of chemistry
Lets start with Ionic Nomenclature
 Because ions combine to form electrically neutral (no charge)
compounds, the names for these compounds do not include
the number of each ion present
 The system assumes you know the formula and charge of the
ions that make up the compound
 This may seem confusing at first. Fortunately there are some
rules about the charges of ions that can help you out! These
rules need to be committed to memory.
Some rules to help you with ionic
nomenclature
Rule 1:
 Metals form (+) ions and are monatomic. The charges on ions
formed from elements in groups 1, 2 and the upper part of 3
(13) is the same as the group #
 For example, group 1A has (+1), 2A has (+2), and the upper part, boron,
aluminum and gallium have a +3 charge.
 The ion name is the same as that of the element (Ca+2 = calcium ion ; Na+ =
sodium ion)
Practice: Give the ion, along with its charge, and provide its
name
Lithium
Gallium
Barium
Francium
Some rules to help you with ionic
nomenclature
Rule 2:
 With the exception of Cd, Zn and Ag, which have only one
charge, the rest of the metals can form ions with multiple
charges. These are represented by a Roman numeral after
the ion name
 For example, Fe+2 is iron (II) and Fe+3 is iron (III), zinc is always Zn+2
 You will want to commit Cd+2, Zn+2 and Ag+ to memory
Practice: Give the name of the following ions
Co+2 and Co+3
Mo+3 and Mo+6
Cd+2
Cu+ and Cu+2
Some rules to help you with ionic
nomenclature
Rule 3:




Non-metals form (-) ions
charge can be predicted by position on PT
Halogens (7A or 17) are 1 away from noble gases so they form -1 ions
The oxygen family (6A or 16) is two spots away from noble gases so they form
-2 ions
 The nitrogen family follows the same trend as well (-3 ions)
 The monatomic ions have the –ide ending
Example: O-2 is oxide, P-3 is phosphide, Br-1 is bromide
Practice: Give the names of the following ions
Se-2
Te-2
N-3
Polyatomic Ions
Polyatomic refers to “many atoms” that are bonded together
that act as one ion
 There is no common trend for the most part, so these are best
committed to memory
 I will give you some common ones I want you to know
 Names of polyatomic ions are not changed
 Example: K+ and SO4-2 form K2SO4 and is properly named
potassium sulfate
Common Polyatomic Ions
Ion
Chemical Formula & Charge
Acetate ion
C2H3O2-
Carbonate ion
CO32-
Bicarbonate ion
HCO32-
Chlorate ion
ClO3-
Chromate ion
CrO42-
Hydroxide ion
OH-
Nitrate ion
NO3-
Nitrite ion
NO2-
Oxalate ion
C2O4-2
Permanganate ion
MnO4-
Phosphate ion
PO4-3
Sulfate ion
SO4-2
Sulfite ion
SO3-2
Binary Molecular Compounds
Binary simply refers to the number 2 since 2 elements are involved in the
compound
These rules are much more simple, but require you to be very attentive
Practice with molecular compounds
SO3
NO
H2O
N2O4
SeF6
Silicon dioxide
Carbon tetrabromide
Carbon monoxide
Diphosphorus pentoxide
Nitrogen triiodide