Molecules of H2O exhibit polarity, an uneven
distribution of charge on different parts
of the overall neutral molecule. The electrons
involved in bonding the molecule together
are attracted more strongly to the oxygen
atom. Thus, the oxygen atom has a slightly
negative charge and the hydrogen atoms have
slightly positive charges.
In a group of water molecules, the slightly
negative oxygen atoms and the slightly positive
hydrogen atoms are attracted to each other.
This attraction between water molecules
is called hydrogen bonding.