Water, or H2O, is compounded using both hydrogen and oxygen. Hydrogen has a positive charge and oxygen has a negative charge. This helps the two compounds to interact with other chemicals such as salt and act as a solvent. The positive charge of sodium links up with oxygen's negative charge, and the positive charge of hydrogen links up with chlorine's negative charge. Oils are not polar however, and would not be able to dissolve, hence why during oil spills, it is a process to clean them up.
