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Why can polar water molecules pull ions out of some materials?

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representations of molecular structure — molecule Several methods of representing a molecule's structure. In Lewis structures, element symbols represent atoms, and dots represent electrons surrounding them. A pair of shared electrons (covalent bond) may also be shown as a single dash. The ball-and-stick model better illustrates the spatial arrangement of the atoms. For aromatic compounds, the Kekulé structure is common, in which each bond is represented by a dash, carbon atoms are implied where two or more lines meet, and hydrogen atoms are usually omitted. Bond-line formulas, similar to the Kekulé structure, are often used for complex nonaromatic organic compounds. Sugars are often drawn as Fischer projections, in which the carbon “backbone” is drawn as a straight vertical line, with carbon atoms implied where horizontal lines intersect the vertical one.

Water molecules are able to pull ions out of solid materials because they are polar, meaning they possess a permanent electric dipole due to their angular shape and the unequal distribution of electrical charge across their atoms.12

In a water molecule, the oxygen atom carries a partial negative charge, while the hydrogen atoms carry a partial positive charge. When an ionic solid is placed in water, these partial charges interact with the ions in the crystal lattice. The positive ends of the water molecules are attracted to the anions, and the negative ends are attracted to the cations.123

This process, known as hydration, allows water to surround and stabilize the individual ions. By replacing the strong forces between the ions in the solid with strong water-ion interactions, water effectively minimizes the energy difference required for the crystal to dissolve, causing the solid to break apart into separate, hydrated ions.31