Water molecules are composed of two hydrogen atoms, bonded to one oxygen atom. Water is a polar molecule because the oxygen atom is slightly negative, while the two hydrogen atoms are slightly positive. One of the chemical properties of water is that it is considered to be the universal solvent. That is because many substances will dissolve in water. These include gases like oxygen and carbon dioxide, salts, sugars, acids, bases. In nature, since water interacts with the environment during the processes of erosion and runoff, many salts and other minerals dissolve in water. Gases from the environment and living things will diffuse in and out of water as well. Therefore, it is easy to see why water in nature is not simply H2O.
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