The atomic nucleus. Uncovering secrets

The modern idea of the atom, confirmed by the works of more scientists and theorists of the twentieth century, allows us to judge with a high degree of probability its structure and the presence in its composition of various elementary particles. The atomic nucleus is the central massive part of the atom. It consists of protons and neutrons, which have received a common name - nucleons. The bulk of the atom (99.95%) is concentrated in its core. Its size is negligible, and the electric charge is positive and is a multiple of the absolute charge of one electron.

By the number of electrons, or the atomic nucleus charge, one can judge the individual properties of the element. This number corresponds to its ordinal number in the periodic table.

The discovery of the atomic nucleus is the merit of E. Rutherford, his experiments in 1911 with the scattering of a-particles during their passage through the substance made it possible to describe the construction of an atom with a high degree of probability.

The atomic nucleus of hydrogen was taken as a basis, and the elementary particle, which forms the basis of the nuclei of other chemical elements, was named after the proton in 1920. But the proton-electron structure of the atom had a number of shortcomings and did not explain many physical phenomena.

To the description of the composition of the nucleus, the science of elementary particles approached closely after the discovery of the neutron. In 1932, J. Chadwick, W. Heisenberg and D. Ivanenko made the assumption of the presence in the nucleus of a particle with a neutral charge. And the building material, from which the atomic nucleus consists, are protons and neutrons. The number of nucleons determines the mass number of the element.

Substances having the same number of protons in the nucleus (the charge of the nucleus) are called isotopes. Isotones are substances that have the same number of neutrons. Substances with the same number of nucleons are isobars.

The physics of the atomic nucleus assumes the presence of smaller composite "bricks" for neutrons and protons. Quarks, gluons, and meson fields form a complex system-the atomic nucleus. A further description of the complex interrelationships of elementary particles is assumed by quantum chromodynamics.

Asking about the stability of the nucleus, which includes both particles that do not have an electric charge (neutrons) or positively charged protons, scientists came to the conclusion that there are especially active nuclear forces in the nucleus that differ from both electromagnetic and gravitational ones.

The influence of these forces is strictly limited by distance, they refer to short-range forces and are limited by a small range of action.

To the nuclear- nucleus charge, nuclear forces show considerable independence. Absolutely different particles are attracted. This phenomenon is clearly manifested when comparing the binding energies of mirror nuclei. This name was given to nuclei with the same number of nucleons, but only the number of protons in one corresponds to the number of neutrons in the other and vice versa. An example can be the nuclei of helium and tritium (heavy hydrogen).

Also, unusual phenomena occur in the process of nucleation. If we calculate the mass of the nucleus and separately the masses of the elements in its composition, then the mass of the nucleus turns out to be smaller. This effect is explained by the release of energy in the process of nuclear synthesis, which was called the binding energy of atomic nuclei. Numerically, it can be determined by calculating the amount of work that will need to be done to split the nucleus into constituent elements (nucleons) without telling them a certain kinetic energy.

In connection with this, the concept of the specific binding energy of the nucleus was introduced. It is calculated in a numerical equivalent per one nucleon, which on the average is 8 MeV / nucleon. As the number of nucleons in the nucleus increases, the binding energy decreases.

The ratio of the number of protons and neutrons is used as a criterion for the stability of atomic nuclei.