An atom, as a separate unit, is built from a nucleus charged with a positive electric charge, and from electrons carrying a negative charge. This is what an atom consists of.
At its center is the nucleus, which is formed by even smaller particles - protons and neutrons. Regarding the radius of the entire atom, the radius of the nucleus is about one hundred thousand times smaller. The density of the core is extremely high.
A stable elementary particle of a nucleus with a positive charge is a proton. A neutron is an elementary particle that does not have an electric charge, with a mass approximately equal to the mass of a proton. The mass of the nucleus consists, respectively, of the total mass of protons and neutrons, the totality of which in the composition of the nucleus is abbreviated as the nucleon. These nucleons in the nucleus are bound by unique nuclear forces. The number of protons in an atom is equal to a certain number of electrons in the atomic shell and, as a consequence, forms the basis for the chemical properties of the atom.
An electron as the smallest particle of matter carries an elementary negative electric charge. Electrons constantly rotate around the nucleus in certain orbits, like the rotation of the planets around the sun. Thus, to the question of what the atom consists of, the following answer can be given: from elementary particles with positive, negative and neutral charges.
The following pattern exists: the size of an atom depends on the size of its electron shell, or the height of the orbit. As part of the answer to the question of what the atom consists of, it can be clarified that electrons are capable of both being added to and removed from the atom. This circumstance turns the atom into a positive ion or, accordingly, into a negative one. And the process of transformation of an elementary chemical particle is called ionization.
A large supply of energy is concentrated in the atomic nucleus , which is capable of being released during nuclear reactions. Such reactions, as a rule, arise in the collision of atomic nuclei with other elementary particles or with the nuclei of other chemical elements. As a result of nuclear reactions , new nuclei are able to form. For example, a reaction can transfer a neutron into a proton, while a beta particle is removed from the nucleus of an atom, otherwise an electron.
A qualitative transition at the center of a proton atom to a neutron can be carried out in two ways. In the first case, a particle comes out of the nucleus with a mass that is equal to the mass of the electron, but with a positive charge, called a positron (the so-called positron decay). The second option involves the capture by the atomic nucleus of one of the electrons nearest to it from the K-orbit (K-capture). So chemical elements are transformed from one to another due to what the atom consists of.
There are such states of the formed nucleus when it has an excess of energy, in other words, it is in an excited state. In the case of a transition to a natural state, the core releases excessive energy in the form of a portion of electromagnetic radiation with a very short wavelength - this is how gamma radiation is formed. The energy released during the ongoing nuclear reactions finds practical application in a number of branches of science and industry.