Note the movement of particles and the orientation of water molecules around the sodium ions versus the chloride ions. See how they cluster around the dissolved ions creating what is known as an hydration cage. Why do they do this?
Draw three pictures:
- A grain of salt made of six units of sodium chloride, surrounded by water molecules which are in the correct orientation based on the attractions and repulsions they would feel from the the particles nearby.
- Show the grain of salt half dissolved. Show each ion in a hydration cage.
- Show the grain of salt completely dissolved. Show each ion in a hydration cage.