Chemical Nomenclature

Chemical Nomenclature



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Does the compound contain a metal and a non-metal or a polyatomic ion?

YES - NO


Metals and non-metals

The location of an element on the periodic table can help you determine if the element is a metal or non-metal. On the table below, the metals are green and the non-metals are light red. The compounds in yellow are called metalloids because they have properties of both metals and non-metals.



Polyatomic Ions

Polyatomic ions are a group of atoms that, when bonded together, behave like ions. The most common polyatomic ions are listed below. Your instructor may ask you to memorize some or all of these.

ammonium NH4+ acetate C2H3O2-
carbonate CO3-2 dichromate Cr2O7-2
hydroxide OH- nitrate NO3-
phosphate PO4-3 sulfate SO4-2
chlorate ClO3- cyanide CN-

A number of other polyatomic ions can be derived from the representative polyatomic ions that end in -ate. The difference between the representative and the derived polyatomic ions are the number of oxygen atoms that they possess. The prefixes and suffixes of these names are changed to represent the different number of oxygens.

A good example is chlorate:
representative ion + one oxygen atom ClO4- perchlorate
representative ion ClO3- chlorate
representative ion - one oxygen atom ClO2- chlorite
representative ion - two oxygen atoms ClO- hypochlorite


Some other examples:
Still others are derived by adding hydrogen to the representative polyatomic ion. When this is done, the prefix "hydrogen" or "bi" is added to the base ion.

Some examples: