The discovery of a proton and a neutron

After it was discovered that the substances consist of molecules, and those in turn - from atoms, a new question arose before the physicists. It was necessary to establish the structure of atoms - what are they made of. E. Rutherford and his disciples took up solving this difficult task. The discovery of the proton and neutron by them took place at the beginning of the last century

E. Rutherford already had suggestions that the atom consists of a nucleus and circling around it at a huge speed of electrons. But what the nucleus of the atom consists of was not entirely clear. E. Rutherford proposed a hypothesis that the nucleus of a hydrogen atom should be part of the atomic nucleus of any chemical element .

This hypothesis was later proved by a series of experiments that resulted in the discovery of a proton. The essence of Rutherford's experimental experiments was that the nitrogen atoms were bombarded with alpha radiation, by which some particles were knocked out of the atomic nucleus of nitrogen.

This process was recorded on a photosensitive film. However, the luminescence was so weak, and the sensitivity of the film was also small, so E. Rutherford offered his students to stay in a dark room for several hours in order to allow the eyes to see barely noticeable light signals.

In this experiment, according to the characteristic light tracks, it was determined that the particles that were knocked out were nuclei of hydrogen and oxygen atoms. The hypothesis of E. Rutherford, which led him to the fact that the discovery of the proton was accomplished, found its brilliant confirmation.

This particle E. Rutherford proposed to call the proton (in the translation from the Greek language "Protos" means the first). It should be understood that the atomic nucleus of hydrogen has such a structure that only one proton is present in it. Thus, the discovery of a proton was made.

The electric charge it has is positive. In this case, it is quantitatively equal to the charge of the electron, only the sign has the opposite sign. That is, it turns out that the proton and electron seem to balance each other. Therefore, all objects, since they are composed of atoms, are not initially charged, and they receive an electric charge when an electric field starts acting on them. In the structure of atomic nuclei of different chemical elements there can be more protons than in the atomic nucleus of hydrogen.

After the discovery of the proton, scientists began to understand that the nucleus of the atom of the chemical element consists not only of protons, because, by conducting physical experiments with the nuclei of the beryllium atom, they found that the mass of protons in the nucleus was four units, while In general, the mass of the nucleus is nine units. It was logical to assume that five more units of mass belong to some unknown particles that do not have an electric charge, otherwise the electron-proton balance would be violated.

James Chadwick, a student of E. Rutherford, conducted experiments and was able to detect elementary particles that emitted from the atomic nucleus of beryllium when they were bombarded with alpha radiation. It turned out that they have no electric charge. It was found that there was no charge due to the fact that these particles did not react to the electromagnetic field. Then it became clear that the missing element of the structure of the atomic nucleus was discovered.

This particle discovered by D. Chadwick was called a neutron. It turned out that it has the same mass as the proton, but, as already mentioned, it has no electric charge.

In addition, it was confirmed experimentally that the number of protons and neutrons is equal to the atomic number of the chemical element in the periodic system.

In the universe you can observe objects such as neutron stars, which are often the final stage in the evolution of stars. Such neutron stars are very dense.