term "chemical element" has long been part of everyday life scientists.So, in 1661 Boyle uses this determination as substances which, in his opinion, it is already impossible to decompose into simpler components - corpuscles.These particles are not changed in the course of chemical reactions and can have different dimensions and weight.
Later, in 1789, Lavoisier proposed the first table, which includes 33 simple body.In the early nineteenth century.John. Dalton introduces atomic and molecular hypothesis on which J. Berzelius then determines the atomic masses of the then known elements.In 1869, DIMendeleev periodic system opens (PS) and the periodic law.However, the modern interpretation of the concept was formed later (after the discovery by G. Moseley and George. Chadwick).In his works, scientists have proved that the charge of the nucleus of an atom is equal to the corresponding (serial) number of the element in the SS DIMendeleev.For example: Be (beryllium), a serial number - 4, the nuclear charge - four.
These discoveries and scientific works have helped to conclude that a chemical element - a kind of atomic nuclei with the same charge.Consequently, the number of protons in them are the same.118 elements now known.Of these, 89 - found in nature, and others - obtained (synthesized) scientists.It is worth noting that the International Union of Chemistry (IUPAC) officially recognized only 112 elements.
Every chemical element has a name and a symbol, which (along with the serial number and the relative atomic mass) are recorded in the SS DIMendeleev.Symbols are written with the help of which types of atoms with equal nuclear charge, is the first letter of their Latin names, such as oxygen (lat. Oxygenation) - Oh, carbon (lat. Carboniferous) - C, etc.If the name of several elements begins with the same letter, to his shorthand add even one letter, for example: lead (lat. Plumbum) - Pb.These designations are international.New types of superheavy atoms with the same charge of the nuclei, which have been opened in recent years and is not officially recognized by IUPAC (numbers 113, 115-118) have a temporary name.
chemical element can exist 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 charge of the nuclei.For instance, He (helium) exist in nature in the form of gas, which molecule consists of a single atom.Also allotropy phenomenon can occur when one element may exist as several simple substances (oxygen O2 and ozone O3).There is also a phenomenon of polymorphism, ie, the existence of several structural variants (modifications).An example of this - diamond, graphite.
also on the properties types of atoms with equal nuclear charge are divided into metals and non-metals.Thus, a chemical element has a specific metal crystal lattice and often in chemical reactions gives outer electrons to form cations, and nonmetal - adds particles to form anions.
during chemical reactions item is saved becauseIt occurs only redistribution of elementary particles in the outer shell and the nucleus of the atoms themselves remain unchanged.
turns out that chemical element is a combination of a certain type of atoms with the same nuclear charge and the number of protons, which exhibit characteristic properties.
