If you are familiar with the structure of an atom, then you probably know that an atom of any element consists of three types of elementary particles: protons, electrons, neutrons. Protons in combination with neutrons form the atomic nucleus of a chemical element. Since the proton charge is positive, the atomic nucleus is always positively charged. The electric charge of the atomic nucleus is compensated by the cloud of other elementary particles surrounding it. A negatively charged electron is that component of the atom that stabilizes the proton charge. Depending on how many electrons surround the atomic nucleus, the element can either be electrically neutral (in the case of equal numbers of protons and electrons in the atom), or have a positive or negative charge (in the case of a shortage or excess of electrons, respectively). An atom of an element that carries a certain charge is called an ion.
It is important to remember that it is the number of protons that determines the properties of elements and their position in the periodic table. D.I. Mendeleev. The neutrons contained in the atomic nucleus have no charge. Due to the fact that the masses of the neutron and proton are comparable and almost equal to each other, and the mass of the electron is negligible compared to them (1836 times less than the mass of the proton), the number of neutrons in the nucleus of an atom plays a very important role, namely: it determines stability systems and decay rate of radioactive nuclei. The neutron content is determined by the isotope (variety) of the element.
However, due to the mismatch between the masses of charged particles, protons and electrons have different specific charges (this value is determined by the ratio of the charge of an elementary particle to its mass). As a result, the specific charge of the proton is 9.578756 (27) · 107 C / kg versus -1.758820088 (39) · 1011 for the electron. Due to the high specific charge, free protons cannot exist in liquid media: they can be hydrated.
The mass and charge of a proton are specific quantities that were found at the beginning of the last century. Which of the scientists accomplished this — one of the greatest — the discovery of the twentieth century? Back in 1913, Rutherford, based on the fact that the masses of all known chemical elements was an integer number of times larger than the mass of a hydrogen atom, suggested that the nucleus of a hydrogen atom was included in the nucleus of an atom of any element. A little later, Rutherford conducted an experiment in which he studied the interaction of the nuclei of a nitrogen atom with alpha particles. As a result of the experiment, a particle flew out of the atomic nucleus, which Rutherford called "proton" (from the Greek word "protos" - the first) and suggested that it is the nucleus of a hydrogen atom. The assumption was proved experimentally during the re-conducting of this scientific experiment in the Wilson chamber.
In 1920, the same Rutherford hypothesized the existence of a particle in the atomic nucleus whose mass is equal to the mass of the proton, but which does not carry any electric charge. However, Rutherford himself could not detect this particle. But in 1932, his student Chadwick experimentally proved the existence of a neutron in the atomic nucleus - a particle, as predicted by Rutherford, with a proton approximately equal in mass. It was more difficult to detect neutrons, since they do not have an electric charge and, accordingly, do not interact with other nuclei. The absence of charge explains such a property of neutrons as a very high penetrating ability.
Protons and neutrons are connected in the atomic nucleus by a very strong interaction. Now physicists agree that these two elementary nuclear particles are very similar to each other. So, they have equal spins, and nuclear forces act on them exactly the same. The only difference is that the proton charge is positive, while the neutron has no charge at all. But since the electric charge in nuclear interactions does not matter, it can only be regarded as a kind of proton label. If the proton is deprived of an electric charge, then it will lose its individuality.