Answer:
Fusion
Step-by-step explanation:
A chemical reaction can be defined as a reaction in which two or more atoms of a chemical element react to form a chemical compound.
On the other hand, a nuclear reaction can be defined as a reaction in which the nucleus of an atom is transformed by being joined (fusion) or split (fission) with the nucleus of another atom of a radioactive element.
This ultimately implies that, during fusion, two smaller atoms fuse to form a larger atom. Thus, fusion involves the joining of two smaller nuclei of atoms to form a single massive or heavier nucleus with the release of energy.
Additionally, the energy that holds the neutrons and protons found in the nucleus of an atom together is known as Nuclear energy.