A neutron is a subatomic particle that is distinct from both protons and electrons. It is one of the fundamental particles that make up atoms. Neutrons have a mass similar to that of protons but carry no electric charge. Protons and neutrons together form the nucleus of an atom, while electrons orbit around the nucleus.
The existence of neutrons was first proposed by physicist James Chadwick in 1932 based on experimental evidence. He showed that there must be a neutral particle in the nucleus to account for the additional mass observed compared to the number of protons present.
Neutrons are not formed by an electron entering the nucleus. Rather, they are formed through a process called nuclear reactions. One common nuclear reaction that produces neutrons is called beta decay. In beta decay, a neutron can be converted into a proton, an electron (beta particle), and a neutrino.
While there are various forces at play within an atomic nucleus, such as the strong nuclear force, which binds protons and neutrons together, electrons do not typically enter the nucleus. Electrons occupy distinct energy levels around the nucleus and are associated with the electromagnetic force. Their interaction with the nucleus is primarily governed by electromagnetic interactions rather than entering the nucleus itself.
In summary, a neutron is a fundamental particle, distinct from a combination of a proton and an electron. It is formed through nuclear reactions and plays a crucial role in the structure and stability of atomic nuclei.