Covalent Compounds – Examples and Properties

This entry was posted on by (updated on )
Covalent Compound Examples
Nonmetals form chemical bonds with each other to make covalent compounds. Covalent compound examples include water, ammonia, chlorine gas, and nitrogen gas.

Covalent compounds or molecular compounds are chemical compounds made of elements connected by covalent bonds. Covalent bonds only form between nonmetallic elements because these elements have the same or similar electronegativity values. Here are examples of covalent compounds and a look at their common properties.

Examples of Covalent Compounds

You can recognize covalent compounds because they consist only of nonmetals. Alternatively, consult a table of electronegativity values. If the electronegativity values of the elements in a compound are identical or similar, then they form covalent compounds. As a general rule, if the electronegativity difference is less than 2 on the Pauling scale, the atoms form covalent bonds. If the electronegativity difference is 2 or more, the elements form ionic bonds.

Examples of covalent compounds include:

  • O2 – oxygen
  • Cl2 – chlorine
  • PCl3 – phosphorus trichloride
  • CH3CH2OH – ethanol
  • O3 – ozone
  • H2 – hydrogen
  • H2O – water
  • HCl – hydrogen chloride
  • CH4 – methane
  • NH3 – ammonia
  • CO2 – carbon dioxide
  • Proteins
  • Carbohydrates (sugars and starch)
  • Lipids (fats)
  • Nucleic acids (DNA and RNA)

Note that organic compounds are all covalent compounds.

The Exceptions to the Rule

In general, if a molecule consists entirely of nonmetals, you can assume it is a covalent compound. However, there is one notable exception. The ammonium cation (NH4+) is so electropositive that it forms ionic bonds with nonmetals rather than covalent bonds. At the same time, the bonds between the nitrogen and hydrogen atoms are covalent. So, compounds such as ammonium chloride (NH4Cl) and ammonium nitrate (NH4NO3) contain both ionic and covalent bonds.

Also, sometimes ionic bonds form with smaller electronegativity differences between atoms. When this happens, one of the atoms is a metal.

Covalent Compound Properties

Covalent compounds share some common properties:

Because of their low melting points, many molecular compounds are liquids and gases at room temperature. Solid covalent compounds tend to be soft or brittle because the covalent bonds (and sometimes hydrogen bonds) are relatively easy to break. The shared electrons within the compounds limit electron mobility, so covalent compounds don’t conduct heat or electricity as well as ionic compounds.

Practice Identifying Ionic and Covalent Compounds

Ionic and Covalent Compounds Worksheet

Test how well you understand covalent compounds using a worksheet. Download and print this PDF worksheet and answer key that asks names of compounds and whether they are ionic or covalent.

[PDF Worksheet] [Answer Key]

References

  • Campbell, Neil A.; Williamson, Brad; Heyden, Robin J. (2006). Biology: Exploring Life. Boston, MA: Pearson Prentice Hall. ISBN 0-13-250882-6.
  • Langmuir, Irving (1919). “The Arrangement of Electrons in Atoms and Molecules”. Journal of the American Chemical Society. 41 (6): 868–934. doi:10.1021/ja02227a002
  • March, Jerry (1992). Advanced Organic Chemistry: Reactions, Mechanisms, and Structure. John Wiley & Sons. ISBN 0-471-60180-2.
  • Stranks, D. R.; Heffernan, M. L.; Lee Dow, K. C.; McTigue, P. T.; Withers, G. R. A. (1970). Chemistry: A Structural View. Carlton, Vic.: Melbourne University Press. ISBN 0-522-83988-6.