Another possibility is that only a portion of one molecule is transferred to the other molecule. This type of reaction occurs, for example, in redox and acid-base reactions. In redox reactions, the transferred particle is an electron, whereas in acid-base reactions it is a proton.
Psychology is the study of mind and behavior. It is an academic discipline and an applied science which seeks to understand individuals and groups by establishing general principles and researching specific cases.
Psychologists study cognitive, emotional, and social processes and behavior by observing, interpreting, and recording how individuals relate to one another and to their environments. They use their findings to help improve processes and behaviors.