Why are ionic compounds soluble in water whereas metals and covalent compounds are insoluble in water?
When ionic bonds form, one atom becomes positively charged, while the other becomes negatively charged. This is because one has to lose a negatively charged electron and another has to gain one. Water is a covalent compound that exhibits the property of polarity, where the electrons hang around one side of the molecule more than the other, giving a water molecule positive and negative poles (negative pole being where the electrons hang around more) Ionic compound tend to form complex lattice networks and structures when left in their comfortable states. Take for example, the complex cube crystal lattice structure of salt. But when the salt is put in water, the polarized molecules act like tiny magnets, pulling on the poles of the salt molecules. The water molecules can pull hard enough to eventually break each salt molecule away from the lattice, dissolving the crystal structure. Metals and most covalent compound do not have poles, and so the water cannot “pull” on the molecules.
