What structures are formed when water molecules surround ions

Solvation shells

Explanation:

Ionic compounds like NaCl dissolve in polar solvents like water.

There are strong ion-dipole attractions between the ions and the water molecules.

The Na⁺ ions attract the negative oxygen atoms of water. The Cl⁻ ions attract the positive hydrogen atoms of water. The ions become surrounded by a solvation shell of water molecules.

The closer the opposite charges can get to each other, the more stable the system. That's why solvation stabilizes the ions.