Преподавателям физики и химии в учебных institutions it is well known that it is much easier to explain a topic by resorting to analogies or using approximate examples, explaining "on the fingers". Although the descriptions given may not fully correspond to the generally accepted model, nevertheless, such an approach gives its results. This is the case in atomic physics.
The chemical properties of substances are relatively simpleexplain, if we use the theory of atomic structure, proposed in 1911 by the English physicist E. Rutherford. Despite the fact that his model is only partially true, this is quite enough to understand the processes that are taking place. Today we will talk about what is the valence electrons and what is their interrelation with the properties of the material being studied. But first, let us recall the planetary model of the structure of the atom.
Rutherford determined that the atom is notas previously thought, but consists of a heavy nucleus at the center and electrons rotating around it. The electric charge of the nucleus is positive (+), and for electrons, in turn, negative (-). Eight years after the publication of his theory of atomic structure, Rutherford was able to conduct a unique, at that time, experience - to turn nitrogen into oxygen. The experiment consisted of "bombarding" the alpha particles with nitrogen atoms. After the collision, an oxygen atom was formed and an "extra" particle with a positive charge, subsequently called a proton.
Теория приобрела законченный вид:the core includes protons, with the help of magnetic forces, the confining electrons in orbits. Since the atom is electrically neutral, and the proton and the electron are attracted, their total quantities are equal. In 1932 physicist J. Chadwick discovered that in the nucleus, apart from protons, there are particles without charge-neutrons. They are responsible for the mass. Depending on the energy of the electron, it can be at a different distance from the nucleus. Valence electrons are those negatively charged particles that:
Under the interaction it is necessary to understand the possibility to leave its atomic orbit or change its trajectory.
Валентные электроны определяются очень просто – according to Mendeleyev's table. For basic elements (except for subgroups, since there are exceptions), the condition is true: the maximum number of valence electrons corresponds to the number of the group in which the element under study is located. The atom, which has a large theoretical number of such particles, reluctantly gives them to other atoms, so it is an oxidizer (takes the missing). Conversely, with a small group number, the valence electrons are easily released by the element, interacting. In this case, we are talking about a reducing agent or a donor atom.
Valent electrons are directly dependent onstate of the atom. So, if one or another way to communicate additional energy from outside (to put it into an excited state), then the orbit of valence particles will become larger.
Data on the valence of materials allow activeuse them, predicting the result. For example, chemical sources of electric current based on electrolytes use such elements that are able to give and receive electrons. Neutral material would be useless in this case. It is not difficult to guess that if all the external electron shells of an atom are filled, then such an element is chemically neutral and does not interact with other atoms (or the interaction force is so insignificant that it can be neglected). A vivid example of this is inert gases.
