How can ionic compounds dissolve in water?

Ionic compounds dissolve in water because the water molecules hydrate the ions.

To dissolve an ionic compound, the water molecules must be able to stabilize the ions that result from breaking the ionic bond.

They do this by hydrating the ions.

Water is a polar molecule. It has a permanent dipole.

The ##"O"## atom has a partial negative charge, and the ##"H"## atoms have a partial positive charge.

When you place an ionic substance in water, the water molecules attract the positive and negative ions from the crystal.

The particles are then free to move around within the solution.

(from 2012books.lardbucket.org)

The positive ions have several water molecules around them, all with their ##"O"## atoms close to the positive ion.

The negative ions have several water molecules around them, all with their ##"H"## atoms close to the negative ion.

The "shell" of water molecules reduces the attractions between the ions. The ions are hydrated.

Here's a video that shows the process in action.