Nomenclature can be defined as the terminology of chemical compounds. It represents the basic "language of chemistry" and, just as the student who is studying French or Spanish must learn the terminology of those languages, so must the chemistry student learn the basic terminology of the discipline.
 

Life certainly becomes a bit easier, and safer for everyone around, if chemistry students are able to read the formulae on the bottles of stock solutions correctly when they have only the names of these substances on their lab sheet or vice versa.
 

Okay, so it's a given......one of the basic, most important tasks that a chemistry student needs to master early on is that of Naming Compounds and Writing Formulae. There are several things that a student can do to make these tasks less tedious.
 

• Learn the correct symbols for the elements. (This is similar to reciting the alphabet...a, b, c..., as well as identifying the symbols we use for each letter.)

 

 
 
 

2. Learn the names and formulae of seven (7) complex ions. The ions and their formulae and charges are:
 

Name of Polyatomic Ion	Formula	Charge
Hydroxide	(OH)-	-1
Bicarbonate (hydrogen carbonate)	(HCO3)-	-1
Nitrate	(NO3)-	-1
Chlorate	(ClO3)-	-1
Carbonate	(CO3)2-	-2
Sulphate	(SO4)2-	-2
Phosphate	(PO4)3-	-3


 
 
 

3. Learn the meaning of several important prefixes and suffixes as they relate to the formulae of polyatomic ions, anions, and acids.
 

Prefix/Sufix	Meaning	Example(s)
-ate	denotes the most common number of oxygen atoms	sulphate, nitrate, chlorate
-ite	one less oxygen than in the "-ate" ion	sulphite, nitrite, chlorite
-ide	ion contains only the atoms whose names are heard	hydroxide, chloride, sulphide nitride
-ic	ending for acid that contains the "-ate" form of the ion	sulphuric, nitric, chloric
-ous	ending for acid that contains the "-ite" form of the ion	sulphurous, nitrous, chlorous
hydro- -ic	prefix and suffix used with acids whose anions contain no oxygen	hydrochloric, hydrosulphuric


 

You can use the meanings for the prefixes and suffixes to expand your repertoire of ions without having to memorize each of them separately.
 

4. Learn the names of the prefixes that are used to denote one (1) through six (6) atoms in a formula.
 

1 = mono-	2 = di-	3 = tri-	4 = tetra-
5 = penta-	6 = hexa-

Applying These Rules


There are three kinds of compounds for which students in high school and general chemistry are usually expected to write formulae or to name. They are ionic compounds, molecular compounds and acids.

Writing Formulae

How to write formulae when given the names of compounds.

This organizer shows the steps to follow when writing the formulae for ionic compounds, molecular compounds, and acids.





Naming Compounds

How to name compounds from their formulae
This organizer shows the steps to follow when naming both ionic compounds and binary molecular compounds.









Adapted from the work of Gwen Sibert at the Roanoke Valley Governor's School