Dipole-dipole attraction between water molecules
The negatively charged oxygen atom of one molecule attracts the positively charged hydrogen of another molecule.
Source
Boundless vets and curates high-quality, openly licensed content from around the Internet. This particular resource used the following sources:
"Hydrogen-bonding-in-water-2D."
http://en.wikipedia.org/wiki/Intermolecular_force%23mediaviewer/File:Hydrogen-bonding-in-water-2D.png
Wikipedia
CC BY-SA.
