Editing Chemical polarity (section)

== Polarity of molecules ==
{{see also|Dipole#Molecular dipoles}}

A molecule is composed of one or more chemical bonds between [[molecular orbital]]s of different atoms.  A molecule may be polar either as a result of polar bonds due to differences in [[electronegativity]] as described above, or as a result of an asymmetric arrangement of nonpolar covalent bonds and non-bonding pairs of electrons known as a full [[molecular orbital]].

While the molecules can be described as "polar covalent", "nonpolar covalent", or "ionic", this is often a relative term, with one molecule simply being ''more polar'' or ''more nonpolar'' than another. However, the following properties are typical of such molecules.

===Boiling point===
When comparing a polar and nonpolar molecule with similar molar masses, the polar molecule in general has a higher boiling point, because the dipole–dipole interaction between polar molecules results in stronger intermolecular attractions. One common form of polar interaction is the [[hydrogen bond]], which is also known as the H-bond. For example, water forms H-bonds and has a molar mass M = 18 and a boiling point of +100&nbsp;°C, compared to nonpolar [[methane]] with M = 16 and a boiling point of −161&nbsp;°C.

===Solubility===
Due to the polar nature of the water molecule itself, other polar molecules are generally able to dissolve in water. Most nonpolar molecules are water-insoluble ([[hydrophobic]]) at room temperature. Many nonpolar [[organic solvent]]s, such as [[turpentine]], are able to dissolve nonpolar substances.

===Surface tension===
Polar compounds tend to have higher [[surface tension]] than nonpolar compounds.{{cn|date=May 2023}}

===Capillary action===
Polar liquids have a tendency to [[Capillary action|rise against gravity]] in a small diameter tube.{{cn|date=May 2023}}

===Viscosity===
Polar liquids have a tendency to be more [[Viscosity|viscous]] than nonpolar liquids.{{cn|date=May 2023}} For example, nonpolar hexane is much less viscous than polar water. However, molecule size is a much stronger factor on viscosity than polarity, where compounds with larger molecules are more viscous than compounds with smaller molecules.{{cn|date=May 2023}} Thus, water (small polar molecules) is less viscous than hexadecane (large nonpolar molecules).