Protons and Neutrons

Atoms contain three basic particles: protons neutrons and electrons. However, we will consider just protons and neutrons at this point:

A proton is a hydrogen atom minus an electron, i.e. a positive hydrogen ion. Its charge is equal in size but opposite in sign to that of an electron but its mass is about 2000 times greater. Neutrons were discovered by Chadwick, who bombarded beryllium with alpha (α) particles. A neutron is uncharged with almost the same mass as a proton. Protons and neutrons are in the nucleus and are called nucleons. Together they account for the mass of the nucleus; the protons account for its positive charge.