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Representing Molecules

Atoms Molecules Ions Chemical Equations On-line practice



Molecules are represented by the combined symbol of the elements that make them up.  This kind of representation is called the chemical formula.


Example :

A molecule of carbon dioxide consists of one carbon atom and two oxygen atoms, hence, it is represented by C02.


The number of each type of atom that make up the molecule is written after their respective symbols in the subscript form.  If there is only one atom of the kind, the subscript is ignored.


Take note :

Some molecules are made up of the same type of atoms but different numbers of them.


These molecules have different chemical properties.


For example, carbon dioxide (CO2) and carbon monoxide (CO) are made up of carbon and oxygen atoms, but carbon monoxide has one oxygen atom less than carbon dioxide.


Hence care should be taken when writing chemical formulae.