2 Why water dissolves ionic compounds

When an ionic compound is added to water, its crystal lattice breaks down into free ions surrounded by water molecules:

• positive ions (cations) are attracted to the negative pole of water (the oxygen atoms);
• negative ions (anions) are attracted to the positive pole of water (the hydrogen atoms).

• The water molecules form a "shell" around each ion (hydration), which keeps the ions apart so they cannot recombine.
• Energy released by hydration compensates for the energy needed to break the lattice.