Introduction to atomic nucleus
The atomic nucleus is located in the core part of the atom, accounting for more than 99.96% of the mass of the atom, and forms atoms with surrounding electrons. The nucleus consists of protons and neutrons. The proton is composed of two upper quarks and one lower quark, and the neutron is composed of two lower quarks and one upper quark. The atomic nucleus is extremely small, its diameter is between 10-12 and 10-13 cm, and its volume only accounts for a few hundred billions of the atomic volume.If you compare the atom to the earth, then the atomic nucleus is equivalent to the size of a baseball field. The quarks and electrons are only about the size of a baseball. The density of the nucleus is extremely large, about 1014 g / cm3. The internal structure of the nucleus can be described by the core-shell model. When a proton or nucleus is filled up from its lowest shell, if a certain shell is filled, it is called a proton or neutron magic number. Magic Core.