1.1 What is Chemistry?

http://www.ck12.org Chapter 7. Chemical Nomenclature

TABLE7.7: Common Names of Covalent Compounds

Formula Common name IUPAC Name

NO nitric oxide nitrogen monoxide

N 2 O nitrous oxide (laughing gas) dinitrogen monoxide

N 2 H 4 hydrazine dinitrogen tetrahydride

H 2 O water dinitrogen monoxide

NH 3 ammonia nitrogen trihydride

PH 3 phosphine phosphorus trihydride

H 2 S hydrogen sulfide dihydrogen monosulfide

H 2 O 2 hydrogen peroxide dihydrogen dioxide

Nomenclature for Organic Molecules

Carbon has a unique ability to form an extremely large variety of molecules with just a few other common elements.
In fact, most of the molecules that make up living beings are composed of just carbon, hydrogen, oxygen, and
nitrogen (with a little sulfur and phosphorus as well). Knowing only the molecular formula for an organic molecule
is not enough to identify it; we also need to indicate how the atoms are arranged within the molecule. For example,
dimethyl ether and ethanol are two molecules with very different properties that both have the molecular formula
C 2 H 6 O. One is an extremely flammable gas, and the other is the intoxicating liquid found in alcoholic beverages.
As a result, most carbon-based molecules have a separate, more complex system of naming that we will cover in
another chapter. However, the formulas for a few common organic compounds can be found in theTable7.8.

TABLE7.8: Names of Common Organic Compounds

Formula Name

CH 4 methane

CH 3 OH methanol

C 2 H 6 ethane

C 2 H 5 OH ethanol

C 3 H 7 OH isopropanol (rubbing alcohol)

C 6 H 12 O 6 glucose

C 12 H 22 O 11 sucrose

Lesson Summary

• Molecular compounds are formed when atoms are held together by covalent bonds, which involve sharing
  electrons rather than transferring them.


• The formula of a binary molecular compound shows how many of each atom are present in the molecule. The
  less electronegative element is generally written first.


• Prefixes are used in the names of molecular compounds to designate how many of each atom are in the
  molecule.

Lesson Review Questions

1. How is a covalent bond characterized?