Chemical Nomenclature
(a.k.a. naming compounds)
Antoine Lavoisier (1743-1794)
“Father of Modern Chemistry”
• Major contributions included
– Established the Law of Conservation of Mass
– Introduced scientific experimenting via the BALANCE
– Invented a system of chemical nomenclature (still used
in part today!)
– Wrote the 1st modern chemical textbook
– Introduced the the 1st 33 elements.
– Demonstrated that water cannot be transmuted to
earth
– AND MORE …
Types of Compounds
The Two main types are:
• Ionic
– Made up of ions (both positive and negative charge)
– Must have no net charge (i.e. combined charge of zero)
– Depend on the attraction between positive and negative
charges of the ions
– Usually a metal is present as a cation
• Molecular (or covalent)
– Made up of atoms that share their outer electrons
– Charge plays no direct role in their formation
– Usually combination of two or more nonmetals.
Naming Compounds
• Easiest way to identify an ionic compound is
whether or not it has a metal present:
– Yes  ionic (e.g. CaCl2)
– No  covalent (e.g. CCl4)
• Ionic compounds are named using the stock
system. (No use of prefixes)
• Covalent compounds require the use of Latin
prefixes to indicate the number of each
element present in one molecule
Naming Binary Compounds
A “simple” or binary compound is a compound
made of only 2 types of elements
• When the first element is a metal:
• The first element (metal) keeps its full name
• The non-metal goes by its root with the suffix “ide” added to the end
Example: NaCl is sodium chloride
•
When there are no metals present
• Same as above except
• Latin prefixes must be used to identify the
number of each element present in the
compound
Example: CO2 is carbon dioxide
Ionic Charges & the Stock System
–
–
–
–
Group 1 metals form 1+ cations (Na+ sodium ion)
Group 2 metals form 2+ cations (Ca2+ calcium ion)
Group 13 metals form 3+ cations (Al3+ aluminum ion)
All other metals (i.e. the transitional metals, Pb, etc.) form
more than one type of cation
• Roman numerals must be used to indicate the charge of the
cation
• Example:
Fe3+ is called iron(III)
FeCl3 is called iron(III) chloride
• Exceptions:
Ag+, Cd2+ & Zn2+
–
–
–
–
Group 15 nonmetals form 3- anions (N3- nitride ion)
Group 16 nonmetals form 2- anions (O2- oxide ion)
Group 17 nonmetals form 1- anions (Cl- chloride ion)
Group 18 nonmetals do not form ions (Zero charge)
Latin Prefixes for Naming Molecules
1)
2)
3)
4)
5)
MonoDiTri
TetraPenta-
CCl4 is carbon tetrachloride
Notes:
6) Hexa7) Hepta8) Octa9) Nona10) DecaC3H8 is tricarbon octahydride
1) Prefixes are used when the compound does not have a metal
present (or when H is the first element in the formula)
2) Prefixes must be used for every element present in the compound
3) mono- is not used for the first element in a compound name (e.g.
carbon dioxide)
Ionic Compounds containing
Polyatomic ions
• Some ionic compounds are made up of polyatomic
ions
• When you encounter this, do not freak out!!
• Become familiar with the polyatomic ions on the
handout
Example: the nitrate ion (NO3-)
• The naming of this type of compound is similar to
that for ionic compounds but no change in suffix.
Example: Ca(NO3)2  Calcium Nitrate
Oxy-Ions
• Polyatomic Ions containing Oxygen can be
represented a number of different ways.
One less Oxygen in the formula change the suffix is
changed from “ate” to “ite”. The ion’s charge,
however, does not change.
Ex.
(NO3)-1  Nitrate vs. (NO2)-1  Nitrite
If two less Oxygens the prefix “hypo-” is placed in front
of the “ite” name.
Ex.
(ClO)-1  hypo- Chlorite
If one more Oxygen the prefix “per-” is placed in front of
the “ate” name.
Ex.
(ClO4)-1  Per Chlorate
Acids
– From the Latin term for “sour”{Acids are sour to the taste}
– Acids are substances that donate protons (H+) (usually
when dissolved in water)
– Chemical formula usually begins with H
Example: hydrochloric acid
HCl(aq) + H2O(l)  H3O+ + Cl- (aq)
Bases
– Taste bitter
– Usually metal containing hydroxides
– Substances that accept protons (H+) when dissolved in
water
Example: potassium hydroxide
KOH(aq) + H3O+  K+(aq) + H2O (l)
Naming Acids
Lets separate acids into 2 types:
–
–
Acids that contain oxygen
Acids that do not contain oxygen
Naming acids containing oxygen:
–
For acids containing “-ate” anions:
1. Use root of the anion (for sulfate, SO42-, use sulfur)
2. Add “-ic” suffix then end with “acid”
Example:
–
H2SO4 is sulfuric acid
For acids with “-ite” anions:
1. Use root of the anion (for sulfite, SO32-, use sulfur)
2. Add “-ous” suffix then end with “acid”
Example:
H2SO3 is sulfurous acid
Naming Acids (cont.)
Naming acids not containing oxygen:
– Add “hydro-” prefix to beginning
– Use root of the anion (i.e. Cl- use chlor)
– Add “-ic” suffix then end with “acid”
Example:
HCl is hydrochloric acid
Name the following acids:
HF
HNO2
HCN
H3PO4
Hydrate Molecules
• A hydrate molecule is a ionic compound
that contains water molecules trapped
inside the crystalline structure.
The Formula includes a dot followed by
the number of water molecules
Ex: Copper(II) Sulfate Pentahydrate
CuSO4 · 5H2O
Hydrate Molecules
The Name of a hydrate molecule would include
two separate names.
The name of the ionic compound followed by the
term ___hydrate. A Greek Prefix would be used
to represent the number of water molecules that
are trapped.
CoCl2 · 2 H2O
 Colbalt(II) Chloride Dihydrate