<human>:  Why is the neutron called a neutron?
<bot>: It’s named after the physicist James Chadwick, who discovered it in 1932. Neutrons are the smallest particles that exist in nature. They are the nuclei of the hydrogen atom, which consists of a single proton and a single electron. Neutrons are also part of the nucleus of all other atoms, including the nuclei of atoms of elements such as carbon, nitrogen, oxygen, and iron. Neutrons are also the nuclei of many radioactive substances, such as uranium and plutonium.