The chemical element is the kind of atoms with the same nuclear charge

The concept of "chemical element" has long been a part of scientists. So, in 1661, R. Boyle uses this definition for substances that, in his opinion, it is already impossible to decompose into simpler components - corpuscles. These particles do not change during chemical reactions and can have different sizes and masses.

Later, in 1789, Lavoisier proposed the first table, which includes 33 simple bodies. At the beginning of the ХІХ century. J. Dalton introduces the atomic-molecular hypothesis, on the basis of which J. Berzelius subsequently determines the atomic masses of the then known elements. In 1869, D.I. Mendeleev opens the periodic system (PS) and the periodic law. However, the modern interpretation of this concept was formed later (after the discoveries of G. Mosley and J. Chadwick). In their works, scientists have proved that the charge of the nucleus of an atom is equal to the corresponding (ordinal) number of the element in the PS DI. Mendeleev University. For example: Be (beryllium), the order number is 4, the charge of the nucleus is +4.

These discoveries and scientific works helped to conclude that the chemical element is a kind of atoms with the same nuclear charge. Consequently, the number of protons in them is the same. Now we know 118 elements. Of these, 89 are found in nature, and the rest are synthesized by scientists. It is worth noting that the International Chemical Union (IUPAC) officially recognized only 112 elements.

Every chemical element has a name and a symbol, which (together with the serial number and the relative atomic mass) are written in the PS DI. Mendeleev University. The symbols used to record types of atoms with an equal nuclear charge are the first letters of their Latin names, for example: oxygen (latent oxygen) - O, carbon (Latin carbon) - C, etc. If the name of several elements starts with the same letter, then another letter is added to its shortened entry, for example: lead (Latin plumbum) - Pb. These designations are international. New superheavy types of atoms with the same nuclear charge, which were discovered during the last few years and not officially recognized by IUPAC (numbers 113, 115-118) have temporary names.

The chemical element can also be in the form of a simple substance. Note that the names of simple substances may not coincide with the names of the type of atoms with the same nuclear charge. For example, He (helium) exists in nature in the form of a gas, the molecule of which consists of one atom. A phenomenon of allotropy can also occur when one element can exist in the form of several simple substances (oxygen O ₂ and ozone O _3). There is also a phenomenon of polymorphism, that is, the existence of several structural varieties (modifications). An example is a diamond, graphite.

Also, in their properties, types of atoms with an equal charge of the nucleus are divided into metals and nonmetals. Thus, the chemical element metal has a special crystal lattice and most often in chemical reactions it gives out external electrons, forming cations, and nonmetal - it adds particles, forming anions.

During the course of chemical reactions, the element is preserved, because There is only a redistribution of elementary particles on external shells, and the nuclei of atoms themselves remain unchanged.

It turns out that the chemical element is a collection of a certain type of atoms with the same charge of nuclei and the number of protons that exhibit characteristic properties.