A process by which two light atoms join to form a new atom of higher atomic mass is
Answer Details
The process by which two light atoms join to form a new atom of higher atomic mass is called nuclear fusion. This happens when the nuclei of two atoms come together with enough force to overcome their natural repulsion and merge into a single, heavier nucleus.
This process releases a large amount of energy, which is why it's of great interest to scientists as a potential energy source. Nuclear fusion is the process that powers the sun and other stars, where hydrogen atoms fuse together to form helium.
In contrast, nuclear fission is the process of splitting a heavy atom into two or more smaller ones, while natural radioactivity refers to the spontaneous decay of an unstable nucleus. A chain reaction refers to a reaction in which the products of one reaction initiate further reactions, which can occur in both nuclear fission and nuclear fusion.