Adhesion is the tendency of certain dissimilar molecules to cling together due to attractive forces. Two materials may form a compound at the join. The strongest joins are where atoms of the two materials swap (ionic bonding) or share (covalent bonding) outer electrons. A weaker bond is formed if a Hydrogen atom in one molecule is attracted to an atom of Nitrogen, Oxygen, or Fluorine in another molecule, a phenomenon called Hydrogen bonding.

For more, visit the Wikipedia entry for aqueous solution, URL: