Introduction and explanation
Water is a polar molecule as the atoms bind in such a way that there are excess electrons on the oxygen side and lack of excess of positive charge on the hydrogen side. Non-polar molecules are molecules that have no charge as the charges cancel each other out. Polar and non-polar molecules cannot form a solution with each other as they have different polarity and they do not attract one another. In a solution with polar and non-polar molecules, the polar molecules will attract with the other polar molecules rather than the non-polar ones. The pulling of polar molecules will result in moving away from the non-polar molecules and therefore this will result in the solution unable to mix.
The attractive dipole-dipole forces between polar substances are stronger than the dipole-induced dipole attractions possible between polar and non-polar substances. Since water is a polar substance, polar and ionic substances are hydrophilic. Non-polar substances are left to interact primarily with themselves and with other non-polar substances. Since they cannot interact as strongly with water as strongly as water interacts with itself, non-polar substances are hydrophobic. When mixed, polar and non-polar materials tend to form separate phases with minimal surface area between them. Surfaces are often curved or spherical because a sphere encloses the largest volume with the smallest surface area. Surface tension is another manifestation of the forces that keep phases apart.
Reference
Why do polar compounds dissolve in water and non-polars compounds don’t? – Yahoo Answers. (n.d.). Retrieved March 4, 2015, from https://au.answers.yahoo.com/question/index?qid=20080827185129AAGzOqX
Polar and Non-Polar Molecules. (n.d.). Retrieved March 4, 2015, from http://www.school-for-champions.com/chemistry/polar_molecules.htm#.VPXbbyu4m-k