7.5: Potential Energy
Potential energy is a stored form of energy that has the potential to do work, and therefore, to be converted into kinetic energy. Gravitational energy, for example, is the potential energy found within gravitational force. Chemical energy is the potential energy stored within molecules by virtue of the bonds between their atoms. Weak bonds have high potential energy, whereas strong bonds have low potential energy.
High Potential Energy
Energy can be stored in the form of chemical bonds. Some bonds are weak, and therefore have high potential energy. For example, hydrogen bonds found between water molecules or those that form between guanine (G) and cytosine (C) nucleotides in a DNA double helix.
Low Potential Energy
Strong bonds, on the other hand, have less potential energy. For example, NaCl molecules contain ionic bonds formed from the electrostatic attraction of sodium cations and chloride anions. Covalent bonds are another example that form from the mutual attraction of molecules for a shared pair of electrons. For example, hydrogen molecules form through the covalent bonding of two hydrogen atoms.
Sugars as Potential Energy
Food has energy stored in the form of the chemical bonds between atoms. When animals ingest sugars, weak bonds between carbon and oxygen as well as those between hydrogen and other carbon atoms are broken to make carbon dioxide and water, which have much stronger chemical bonds. This process releases energy in the form of ATP, that is then used to drive biochemical reactions elsewhere in the cell.