school energy&environment

Chemical properties of water

The chemical formula of a molecule of water is H2O: two atoms hydrogen (H2) linked to one atom oxygen (O). The atom electrons (particles with a negative charge) establish links between themselves. Oxygen is more able to keep them close to it than hydrogen. The water molecule results to be charged negatively near the atom of oxygen and positively near the atom of hydrogen. Since opposites attract, the water molecules tend to join together like magnets.
Water can melt many substances
Water is called the universal solvent since it can solve more substances than any other liquid. And we are very lucky it can: if it could not, we could not drink a cup of hot sugared tea, because the sugar would remain at the bottom of the cup. This is why the waters of rivers, streams, lakes, seas and oceans that may look pure at first sight contain in fact a huge number of solved elements and minerals released by rocks or by the atmosphere. Wherever it flows, above ground, underground or inside our body, water solves and carries an extremely high amount of substances. Water thus performs a precious task: that of carrying, sometimes to long distances, the substances it encounters along its way. Pure water, like distilled water, has a pH of 7 (neuter). Seawater is essentially alkaline, having a pH of around 8. Most fresh water has a pH between 6 and 8, apart from acid rains, of course, whose pH is below 7.