Acovalent bond between to atoms results when the atoms lose or gain electrons share electron pairs transfer valence electrons conmpletely from one atom to the other realease energy

The human eye contains a molecule called 11-cis-retinal that changes shape when struck with light of sufficient energy. the change in shape triggers a series of events that results in an electrical signal being sent to the brain that results in vision. the minimum energy required to change the conformation of 11-cis-retinal within the eye is about 164 kj/mol.