What are Molecule Systematic Names and Common Names?

Molecule Systematic Names are derived with a nomenclature system for simple organic molecules.

Some rules used by the nomenclature system for binary (two-element) molecules are:

• The more electropositive atom is written first and the more electronegative element is written last with an -ide suffix.
• The Greek prefixes are used to dictate the number of a given element present in a molecular compound.
• Prefixes can be shortened when the ending vowel of the prefix “conflicts” with a starting vowel in the compound.

Here is the list of Greek prefixes used in the nomenclature system:

Number of   Greek  
 Elements   Prefix
---------   ------
        1   mono- (not used on the first element)
        2   di-
        3   tri-
        4   tetra-
        5   penta-
        6   hexa-
        7   hepta-
        8   octa-
        9   nona-
       10   deca-

Examples of systematic names for binary molecules are:

Systematic Names       Formula 
--------------------   -------
Dihydrogen Monoxide    H₂O
Carbon Dioxide         CO₂
Nitrogen Monoxide      NO
Dinitrogen Monoxide    N₂O
Disulfur Dichloride    S₂Cl₂
Dichlorine Heptoxide   Cl₂O₇

The diagram below shows you how the systematic name Dichlorine Heptoxide is derived for Cl₂O₇:

Molecule Common Names are commonly used names for some popular molecules.

Examples of common names are:

Common Names      Formula 
---------------   -------
Water             H₂O
Ethanol           C₂H₆O

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