The diagram below illustrates the concept of a
dissolved salt where ions of Na+
and Cl- are surrounded by a sea of H2O molecules.
The + and -
superscripts denote the charge of each ion, which is controlled by the balance of electrons
and protons contained in the ion.
1. Notice how the positive-charged ions of Na+
are attracted to the negative charged, O2-(oxygen),
side of the water
molecule. Conversely, the Cl- ion is attracted to the side of the H2O molecule with
the two Hydrogen ions with positive charges (H+).
2. Why are some ions attracted to each other
while others are repelled from each other?
Remember that "opposite" charges
attract and "like" charges repel -- so it has to do with the atomic charges of
the respective ions (Na+ &
Cl-) and the nature of the distribution of
charges within the water molecule (H2O). The water molecule (H2O) has a slightly positive charge on H+
side and slightly negative on the O2-
side of the water molecule.