What distinguishes nuclear reactions from chemical reactions?

Nuclear reactions involve changes in an atom's nucleus, while chemical reactions involve changes in the electron shells.

Nuclear reactions and chemical reactions are two fundamentally different processes that occur in matter. The primary difference between them lies in the part of the atom they involve and the energy changes associated with them.

In a nuclear reaction, the nucleus of an atom is altered. This can occur through processes such as fusion, where two atomic nuclei combine to form a larger nucleus, or fission, where a large nucleus splits into two smaller ones. Nuclear reactions are typically accompanied by a significant change in energy, often releasing energy in the form of radiation. This is because the forces involved in nuclear reactions, namely the strong nuclear force and weak nuclear force, are much stronger than those involved in chemical reactions.

On the other hand, chemical reactions involve changes in the electron shells of atoms. These reactions occur when atoms share, donate or accept electrons in order to achieve a stable electron configuration. The energy changes in chemical reactions are much smaller than in nuclear reactions, as they involve the electromagnetic force, which is weaker than the nuclear forces.

Furthermore, nuclear reactions can change one element into another, as the number of protons in the nucleus (which determines the element) can change. In contrast, chemical reactions cannot change one element into another, as they only involve changes in the way atoms are bonded together, not changes in the atoms themselves.

In terms of their practical applications, nuclear reactions are used in nuclear power plants and atomic bombs, while chemical reactions are involved in a wide range of processes, from the metabolism of food in our bodies to the combustion of fuel in cars.

In summary, while both nuclear and chemical reactions involve changes in atoms, they differ in the part of the atom they involve, the forces and energy changes associated with them, and their practical applications.