chemStd 6b:Students know how to describe the dissolving process at the molecular level by using the concept of random molecular motion

To know how to describe the dissolving process by randomly moving molecules, we first need to know what dissolution is. Dissolution is the process of dissolving a solid substance into a solvent to make a solution. In the picture on the side, we see a solute and solvent breaking into molecules. As the molecules randomly mix, they combine together to create a solution.
When a crystal of salt is dropped into a beaker of water, it is bombarded by randomly moving water molecules which surround each ion and carry it into solution. It is this interaction between moving water molecules and the particles in the crystal that causes it to dissolve. Molecules randomly flow in all directions until there is an equal concentration throughout the solution. Heat speeds up this process. When an ionic compound dissolves in water, the water molecules separate and disperses the ions into the liquid. The positive ions are attracted to the negative ions.

Here's a video that describes sodium chloride being dissolved:

Here's another example of how an ionic compound dissolves in water: