The Anatomy of a Water Molecule

Trite, but true:   if there was no water, there would be no life. Water is something we take for granted. Just think, a combination of three nuclei and ten electrons constitutes water (H2O), which is unique among the more than 15 million chemical species.

The Anatomy of a Water Molecule

A molecule joins together with atomic nuclei and electrons to let us examine the effect of water (H2O). The water molecule is one of the most stable and most difficult to dispose. One cannot get rid of the water molecule. One dries a wet dish. The water molecules transfer from the dish to the towel. As the towel dries, water evaporates and becomes a gas (in the form of vapor). The gas escapes into the atmosphere and is a part of the watercycle.

In water, the two hydrogen nuclei bind to the central oxygen atom by a pair of shared electrons This shared electron pair is a covalent chemical bond. Only two of the electrons pair are needed in H2O for the chemical bond. The other four electrons are non-bonding pairs. They stay far apart, but the non-bonding pair remain close to the oxygen atom. These four non-bonding atoms exert aversion against the two covalent bonding pair next to the hydrogen. Basically, this means that the two hydrogen atoms are closer together. This explains why the H2O molecules are bent.

Molecules are smaller than light waves and cannot be directly observed. Computers can generate an image that show the electron distribution. It looks like Mickey Mouse. The oxygen molecule is the largest and the hydrogen molecules are Mickey’s ears. Ten electrons are around the structure and give off negative electric charge.

The Strange Make-Up of Water

Water has properties that are different from other molecules of the same size. Chemists call this the “anomalous” properties of water. Water properties are not mysterious – they are predictable based on the oxygen atom’s charge. 

A look at the Anomalous Properties of Water.

∞ Water Solid is less dense than liquid. This explains why ice floats in a glass of water. Pipes, when frozen, burst because the expansion of water O – H-bonds shove the molecules farther apart.

∞ Water Boiling point does not follow the chemical rule. The molecule, H2O, is lightweight. Therefore, it should boil at 130º F (-90º C). Instead, it has a higher boiling point, 212º F (100º C). This is because H-bonding does this. Otherwise, water would be a gas instead of a liquid.

Surface Tension

In summer, if one were to leave standing water in a bucket, would see a mosquito or water strider walk on the surface of the water. This is because of the surface tension of water. It is similar to “skin”.  The molecules near the surface experience forces going sideways and down-ward. It is caused by the hydrogen-bonding forces.

How Water Molecules Change in Sea Water

Salt and other dissolved molecules can move through H2O by a process called diffusion. The dissolved salts tent to attract water molecules. The hydrogen in H2O separates to make ions. The ions are what attracts the water to saline molecules. Water has the power to dissolve. Water dissolves gases, oxygen and carbon dioxide, to form an area for sea water animal life.

The cycle of life goes on from this miraculous little molecule that provides life for all living creatures.