How Is Hydrogen Bonding Important to Chemistry?

How Hydrogen Bonding Works

• The negatively charged atom serving as the point of attraction for the hydrogen atom is referred to as the hydrogen-bond donor. Once the two molecules are close enough to correspond, the donor pulls the electron cloud surrounding the hydrogen atom, leaving the hydrogen atom with a slightly positive total charge. As hydrogen is a much smaller atom relative to the other kinds of molecules, it will interact in this way; the resulting shift of charge has a high density, forming the hydrogen bond.

An Example: Water

• One of the most common examples of hydrogen bonding occurs between water molecules (H2O). The single atom of oxygen found in water contains two pairs of electrons, thus creating two possible sites for bonding with the hydrogen atom of another molecule of water. This allows each water molecule to potentially bond with four total other water molecules, which results in each of the molecules growing larger as they gain electrons. This is what causes water to have such a high boiling point, as a greater temperature is needed to break the bonds.

What Makes Hydrogen Bonding Important in Water

• The effect of requiring a greater amount of energy to break several hydrogen bonds in liquid water has some interesting chemical and environmental effects. One of the most significant of these in daily practice relates to why mammals are able to keep cool through sweating. Because of the high amount of heat required to disrupt the water molecules̵7; hydrogen bonds, the evaporation of sweat allows the body to get rid of a lot of excess heat. This also has the effect of cooling ground areas near large bodies of water.

Other Uses of Hydrogen Bonding

• Though a single hydrogen bond is significantly less powerful than a covalent bond, the presence of many hydrogen bonds interacting together can become quite significant. Many other important chemical phenomena are a direct result of these aggregate sites of hydrogen bonding. For instance, the double helix of our DNA is fused through hydrogen bonding. As well, many antibodies that power our immune system against sickness are able to bond to the antigens they target using hydrogen bonding. Without these very basic structures, we would likely not survive or even exist.