Where is potential energy stored in chemical bonds within biomolecules?

• A. In the kinetic energy of atoms
• B. In the arrangement of electrons in bonds
• C. In the position of the electrons that form the bond
• D. In the thermal energy of the surroundings

Answer: (C)

Potential energy in chemical bonds comes from where the electrons sit relative to the nuclei in a molecule. When atoms bond, electrons occupy a region between the nuclei in a way that lowers the system’s energy compared with separated atoms. The exact energy depends on the electrons’ positions within that bond region; shifting those positions—by stretching or breaking the bond—changes the potential energy. So the energy stored in a bond is tied to the position of the electrons that form the bond.

Other kinds of energy described in the other options relate to motion or the environment, not the stored bond energy. The arrangement of electrons in bonds is related, but the most precise way to say where the energy sits is in the positions of those bonding electrons.