Chemical elements, a set of atoms with a certain nuclear charge Z. D. I. Mendeleev defined chemical elements as follows: "material parts of simple or complex bodies that give them a known set of physical and chemical properties." Relationships elements chemical reflects . Ordinal (atomic) number of the element in it equal to the charge nucleus, which in turn is numerically equal to the number of protons contained in the nucleus. For each element, varieties are known - isotopes (existing in nature and obtained artificially by nuclear fusion), differing in number in the nuclei. A set of atoms, characterized by a certain combination and in the nucleus, called. . The atomic mass of a chemical element is calculated based on the values ​​of the masses of all its natural isotopes, taking into account their relative abundance, and is expressed in. for which 1/12 of the mass of the carbon atom 12 C is taken. The atomic mass unit is 1.66057 x 10 -27 kg. The total number and in the nucleus is BUT.

In nature, there are elements with a serial number (number of protons) Z= 1-92, except for (Z= 43) and (Z=61), which are obtained through nuclear reactions. Elements with Z = 85 (astatine) and with Z = 87 (francium) occur in negligible amounts as members of the natural radioactive series and . All known transuranium elements (Z=93-109) are obtained artificially.

The forms of existence of chemical elements in free form are simple substances, which are subdivided into and non-metals. Characteristics metals: high electrical conductivity and due to the presence of free electrons not associated with certain atoms; ability to form positively charged chemical interactions. The boundary between metals and non-metals is rather blurry.

Many chemical elements exist in the form of several simple substances, which may differ in the number in (for example, oxygen O 2 and O 3), the type of crystal lattice (for example, modifications -, carbine) or other properties. This phenomenon is called allotropy, in the case of allotropy - a kind . The number of simple substances now known exceeds 500. Since the nuclear charge is the defining feature of the elements, the element retains its individuality in chemical reactions; there is only a redistribution of external electron shells atoms, while remaining unchanged. Each chemical element is characterized by which atoms of a given element can manifest in chemical compounds.

Chemical elements are classified according to their position in the periodic table. s-, p-, d- and f-elements. To s- elements include H, He, as well as the main subgroups of groups I and II of the periodic system, to p-elements - elements of the main subgroups of III-VIII groups, to d-elements - side subgroups of groups I-VIII (except for and. belonging to f-elements); s- and R elements are called intransitive, d- and f-elements - transitional. Chemical elements all of which are radioactive are called radioactive.

All chemical elements were formed as a result of diverse complex processes of nuclear fusion in stars and outer space. These processes are described by various theories of the origin of elements, which explain the peculiarities of the abundance of elements in space. Hydrogen and are the most common in space, and in general, the abundance of elements decreases as Z increases. The same trend persists for the abundance of chemical elements on Earth, but on Earth it is most common (47% of the mass of the earth's crust), followed by (27.6 %), (8.8%), (4.65%). These elements, along with . . and make up more than 99% of the mass of the earth's crust, so that the remaining chemical elements account for less than 1%. The practical availability of chemical elements is determined not only by their abundance, but also by the ability to concentrate in the course of geochemical processes. Some chemical elements do not form their own minerals, but are present as impurities in the minerals of others. They are called scattered (rubidium, ., etc.). Chemical elements, the content of which in the earth's crust is less than 10 -2 -10 -3%, are united by the concept of "rare".
occur in nature exclusively in the form of simple substances, some elements - in the form of simple substances and compounds, but most - only in the form of compounds. Most simple substances under normal conditions are solid; and - . hydrogen, . oxygen, noble gases, and - gases.

In different historical epochs, different meanings were put into the concept of "element". The idea that all chemical elements have a material character, and their number can be large, was expressed in 1661 by R. Boyle; he also proposed the first definition of an element as a substance indecomposable into its component parts. In 1789, A. Lavoisier characterized the elements as the limit of decomposability of substances and compiled the first list of chemical elements - the "Table of Simple Bodies". In 1803-04, J. Dalton introduced the concept of atomic (mass) and published the first table of atomic weights of chemical elements. D. I. Mendeleev clearly separated the concepts of an element and a simple substance.

The discovery of chemical elements existing in nature took place over a long period of time (table). Chronological The sequence of discoveries was determined by the specific properties of chemical elements and the development of new methods chemical analysis. Even in antiquity, mercury, iron, tin, carbon became known. They are easily extracted from compounds containing them or are found in native form. In the Middle Ages, during the period of domination of alchemy, they were discovered and studied, and in 1669 - (moreover, the first element whose discovery can be dated). The massive and largely conscious discovery of chemical elements began in the middle of the 18th century, which was facilitated by the development of pneumatic (the study of the properties of gases) and, in particular, chemical analysis. The result was the detection of hydrogen, oxygen, ..., chlorine, as well as more than 20 metals. Electrochemical method made it possible to obtain sodium, potassium, magnesium and calcium in a free form. . introduced into the chem. practice by R. Bunsen and G. Kirchhoff in 1859-60, contributed to the discovery of thallium, gallium and noble gases, as well as several rare earth elements. Using the radiometric method, , radium, and were discovered. In the 1920s thanks to x-ray analysis, hafnium,. Synthesis artificial elements chemical has been carried out since the late 30s.

CHRONOLOGY OF DISCOVERY OF CHEMICAL ELEMENTS EXISTING ON EARTH

Nitrogen 1772 D. Rutherford

Actinium 1899 A. Debjorn

Aluminum 1825 X. Oersted
1894 W. Ramsay, J. Rayleigh

Barium 1774 K. Scheele, Y. Gan

Beryllium 1798 L. Vauquelin

Bohr 1808 J. Gay-Lussac, L. Tenard

Bromine 1826 A. Balard

Vanadium 1830 N. Sefstrom

Bismuth Obtained in the Middle Ages

Hydrogen 1766 G. Cavendish

Tungsten 1781 K. Scheele

Gadolinium 1886 P. Lecoq de Boisbaudran

Gallium 1875 P. Lecoq de Boisbaudran

Hafnium 1923 D. Coster, D. Hevesy

Helium 1895 W. Ramsay, W. Crookes

Germanium 1886 K. Winkler

Holmium 1879 P. Cleve

Dysprosius 1886 P. Lecoq de Boisbaudran

Europium 1901 E. Demarce

Iron Known since antiquity

Gold Known since antiquity

Indium 1863 F. Reich, T. Richter

Iodine 1811 B. Courtois

Iridium 1804 S. Tennant

Ytterbium 1878 J. Marignac

Yttrium 1794 Y. Gadolin

Cadmium 1817 F. Stromeyer

Potassium 1807 G. Davy

Calcium 1808 G. Davy

Oxygen 1774 J. Priestley, K. Scheele

Cobalt 1735 G. Brandt

Silicon 1823 I. Berzelius

Krypton 1898 W. Ramsay, M. Travers

Xenon 1898 W. Ramsay, M. Travers

Lanthanum 1839 K. Mosander

Lithium 1817 Y. Arfvedson

Lutetium 1907 J. Urbain

Magnesium 1808 G. Davy

Manganese 1774 K. Scheele, J. Gan

Copper Known since antiquity

Molybdenum 1778 K. Scheele Arsenic Obtained in the Middle Ages

Sodium 1807 G. Davy

Neodymium 1885 C. Auer von Welsbach

Neon 1898 W. Ramsay, M. Travers

5. Substance is any set of atoms and molecules that is in a certain state.

An element is a substance consisting of only one type of atom that cannot be separated into simpler substances through chemical reactions. Some elements can exist in different physical forms if their atoms have the ability to combine in different ways. different forms such compounds are called allotropes. Diamond and graphite are allotropes of carbon.

In diamonds, each carbon atom is tightly bonded to four other atoms. This is why diamonds are so hard.

In graphite, each carbon atom is bonded to other carbon atoms. Atoms are connected as if in layers, their bonds are very weak, so graphite has such a layered structure.

The third allotrope of carbon is Buckminsterfullerin. This structure consists of 60 atoms forming a hollow sphere inside the compound. Other elements of the periodic system also have their own allotropes. For example, phosphorus, tin, sulfur and others. 6. There are a little over 100 chemical elements however, they form at least 2 million compounds. Compounds are made up of atoms of two or more elements linked together to form new substances.

Regardless of the amount of matter, its constituent elements are always in the same proportion.

Connections have two distinctive features: - they cannot be separated by physical means, such as filtration or separation, because they are connected by a chemical bond; - they have different properties than their constituent elements.

7. During chemical reaction atoms in a substance, called reactants, rearrange and form new substances, called products.

During a chemical reaction, energy is always absorbed or released. Gap chemical bonds absorbs energy, and the formation of bonds contributes to its release. This is usually thermal energy, although some reactions absorb or emit light energy.

8. Overwhelming number solids have crystal structure. AT crystalline substances the particles from which crystals are built are placed in space in a certain order and form a spatial crystal lattice. The crystal lattice is built from repeating identical structural units, individual for each crystal. Such a structural unit is called an elementary cell. The simplest elementary cell contains eight nodes at the vertices of the cube. Since eight elementary cells adjoin each "vertex-node", then there is one atom for each elementary cell. However, an elementary cell can also be constructed so that it contains additional nodes located inside the volume of the cube or on its faces - such lattices are called complex. There are 14 types of crystal lattices in total.

9. Depending on the conditions, the same substance can be in different states: in solid, liquid or gaseous (for example, water, ice, water vapor). These states are called aggregate. Molecules of the same substance in a solid, liquid or gaseous state are the same, do not differ from each other, only their mutual arrangement.

10. 1) What are substances made of? 2) Why are substances different, and why can some substances turn into others? Science has spent more than 2,000 years to fully resolve these complex issues. The result was an atomic-molecular theory, the main provisions of which can be formulated as follows:

1.) All substances are made up of molecules. A molecule is the smallest particle of a substance that has its own chemical properties.

2.) Molecules are made up of atoms. An atom is the smallest particle of an element in chemical compounds.

Different elements correspond to different atoms.

3.) Molecules and atoms are in continuous motion.

4.) In chemical reactions, molecules of one substance are converted into molecules of other substances.

Atoms do not change in chemical reactions.

The above scientific facts about molecules say:

First: that in each molecule not only atoms of one or several types are concentrated, but also a certain amount of molecular energy, which is concentrated not in the atoms located in this molecule, but in its internal space. The presence of molecular energy in each of the molecules follows from the following scientific facts:

1. “During a chemical reaction, energy is always absorbed or released. The breaking of chemical bonds absorbs energy, and the formation of bonds contributes to its release. This is usually thermal energy, although some reactions absorb or emit light energy. "("Mixtures and Compounds. "Moscow. ROSMEN. 2002, p. 26)

2. “Atoms in molecules are connected to each other in a certain sequence and distributed in space in a certain way. Bonds between atoms have different strengths; it is estimated by the amount of energy that must be expended to break these bonds. ("Physics". Schoolchild's reference book. Company "Key-S". Moscow. 1995, p. 218)

Since, according to the atomic-molecular theory, "atoms do not change during chemical reactions," as a result, their internal energy, which means that the atoms of substances between which a chemical reaction occurs do not absorb or release energy. Consequently, it can be absorbed or released only by “what connects the atoms to each other in a molecule in a certain sequence and distributes it in space in a certain way,” i.e., only what is in the internal space of the molecule.

Secondly, about the fact that forces of a certain content, properties and magnitude are concentrated in each molecule, which connect the atoms in it with each other in a certain sequence and distribute them in a certain way in molecular space.

The question is, what are these forces? Modern chemical science gives the following answer to this question:

“Only a few chemical elements (noble gases) under normal conditions are in the state of a monatomic gas. The atoms of other elements, on the contrary, do not exist individually, since they can interact with each other or with atoms of other elements, forming more or less complex particles. Among the particles formed by a collection of atoms, molecules are usually distinguished, molecular ions and free radicals. Therefore, there is a reason why atoms "bond" to each other. This reason is called "chemical bond", it is due to the fact that electrostatic forces act between atoms, i.e., the forces of interaction of electric charges, the carriers of which are electrons and atomic nuclei.

It has been proven that in the formation of a chemical bond between atoms, the main role is played by electrons located on the outer shell and, therefore, associated with the nucleus the least strongly, the so-called valence electrons. »

("The Beginnings of Chemistry". Exam Publishing House. Moscow. 2003, p. 80) It follows that the forces that connect atoms in a molecule to each other in a certain sequence and distribute them in a certain way in molecular space are electrostatic forces, i.e., the forces of interaction of electric charges, the carriers of which are electrons and nuclei of atoms. Modern physical science describes the concept of "electrostatic forces" as follows:

“The interaction of fixed electric charges is called electrostatic or Coulomb. Accordingly, the field of fixed charges is also called electrostatic. "(Physics. Moscow. 1995, p. 123)

"Lines of tension electrostatic field are not closed: they start on positive charges and end on negative charges (or go to infinity) "("Physical Encyclopedic Dictionary. Moscow. " Soviet Encyclopedia» page 895)

But the electric charges of electrons in atoms are not stationary, since the electrons revolve around the nucleus of an atom at the speed of light, which means that it also rotates at the same speed. electric charge. In addition: “The dimensions of all atoms are ~ 10 -10 m. And the size of the nucleus is 5 orders of magnitude smaller, only ~ 10 -15 m.

Visually, this can be imagined as follows: if an atom is enlarged to the size of a 20-story building, then the nucleus of the atom will look like a millimeter speck of dust in the central room of this house. »

("Substance and Energy". ROSMEN. TD "Publishing house World of Books". Moscow. 2005 p. 656)

Consequently, the distance between the nucleus of one atom and the outer electrons of any other atom is several orders of magnitude larger than inside the atom. With such huge distances between positive charge nuclei of one atom negative charges external electrons of another atom, and even revolving around it at the speed of light, interaction is hardly possible. But even if we assume that such interaction between them is still possible, then it is possible only if the following conditions are met:

a. / the speed of movement of free atoms towards each other should be such that there is enough time for the interaction to occur between their opposite charges

b. / at the same time, they must pass relative to each other at a distance that would ensure the occurrence of interaction between their opposite charges.

The presence of such conditions in the global orbital flow of atoms for two or more free atoms can still be assumed, but for the number of free atoms from which planets, their satellites, etc., were subsequently formed, the existence of such conditions is simply not realistic.

Therefore, the electrostatic forces of atoms could not be the forces that created from free atoms various types and types of molecules and chemical compounds in the form of planets, their satellites, asteroids and comets. This is also explained by the fact that the process of formation of various types and types of molecules and chemical compounds from free atoms and the process of a chemical reaction between the initial substances are fundamentally two different processes. The first is primarily the creation of "chemical bonds" between free atoms, while the second is primarily a change in "chemical bonds" between the atoms of the original substances. The question is, what were the forces that connected the atoms that were in a free state in the global orbital energy flows and as a result of this created molecules, chemical elements and compounds, planets, their satellites, asteroids and comets? Since it is indisputable that molecules and chemical compounds were created in such a huge volume of outer space as ours solar system, then concentrate the energy and atoms of one or the same various kinds and in a certain amount of them, both in the molecular volumes of space, and in such huge volumes of outer space as planetary, it is possible only in one physical way - as a result of their compression by forces of a certain content, properties and magnitude. It is not possible to do this in outer space in any other way. Consequently, the forces that created planets, their satellites, asteroids and comets from the global orbital flows of atoms were, first of all, forces of compression. Let's call these forces - aggregate forces, and the energy they possessed - aggregate energy - these are thermal, electromagnetic and electronic flows emitted by the Sun.

From a physical point of view, the essence of the process of formation of atoms was the compression by atomic forces of huge quantities elementary particles certain types in the elementary plasma, as a result of which they were concentrated in the nuclear volume of outer space and the atomic energy configurations that made up the atomic forces were combined with certain types of given elementary particles in a certain number of them. The essence of the process of formation of molecules, chemical elements and chemical compounds consisted in the compression by global aggregate forces of vast quantities of atoms of various types concentrated in each of the orbital flows of atoms revolving around the atomic plasma, which was expressed in their constant pressure on atoms throughout their orbital path. As a result of this, the atoms were absorbed by the aggregate forces and wound around each other and thereby the formation of “aggregate lumps” from them, in which the aggregate forces consisting of various types of energy structures, contracting around the absorbed atoms, combined with them forming substances of a certain type. The connection of atoms with a specific energy structure for each specific atom was expressed in the transformation of various types of energy flows that make up this energy structure into the energy of communication between them. The main such types of energy flows were thermal and electromagnetic energy flows emitted by the Sun.

For the energy structure itself, the connection with atoms was expressed in its “reification” in a certain volume of outer space.

Thus, therefore, for any substance, the functional purpose of its energy structure for the atoms that make up its composition is to establish an energy connection between them in a certain volume of outer space, and the functional purpose of the atoms that make up this substance for its energy structure is to "reification" in the same volume of outer space.

Each specific atom performed and performs this function in relation to the thermal energy flows of a specific energy structure through its retracting forces, which, drawing in these thermal energy flows, were thereby connected to each other through them, and as a result of this, they formed an energy bond between atoms. . The number of pulling forces that each atom can have is determined by the number of atomic forces that it has. The spiral rotation of the atomic force around the center of the atom forms voids between the turns of its spiral. As a result, on the opposite side of the atomic force, in the course of its rotation, elongated spiral lines of force, rotating along the axis of rotation of the atomic force and each subsequent turn, which turned out to be less than the previous one, thereby forming a “retracting funnel”, in which a retracting force of a certain magnitude arises, capable of drawing in thermal energy on the long distance from the atom. When the pulling force of an atom came into contact with thermal energy, the first began to draw the second into itself, and the latter began to move along its lines of force with high speed. As a result, a thermal energy flow of a certain diameter and length came out of the narrow part of the "power funnel". Let's call such a heat flow of energy - structural. Since the atomic forces, the forces possessed by the atom, have different magnitudes, as a result of this they also create pulling forces of various magnitudes. The retracting forces, having a large value, respectively, were the first to interact with the structural energy flows of the energy structure, and therefore they were the first to connect with them.

If an atom is in a free state in a certain volume of space, then its function driving force in this space perform: - either its external retracting forces created by its "external" atomic forces, provided that in the same volume of space there are only thermal energy flows. In such a volume, the atom moves towards the movement of the structural energy flow or the concentration of structural energy flows - or the negative electrostatic forces of its outer electrons, when there is no thermal energy around the atom, but there is electromagnetic energy, or the latter dominates the former.

Atoms connected to each other through the same structural energy flow in closed system form a molecule. The structural flow of energy rotating through two molecules and thus connecting them into a closed system forms an intermolecular energy bond. The same molecule can have several intermolecular energy bonds. In relation to electromagnetic energy flows, the atoms performed and continue to perform their functional purpose through their electrons, i.e. through their electrostatic forces. Atoms that have a large number of atomic forces, respectively, also have a large number of electrons and, consequently, also have a large amount of electrostatic forces, which, as a rule, exceeds overall value its external pulling forces. As a result of this, such atoms first of all interacted with the electromagnetic flows of the energy structure and only secondarily with its structural energy flows. Therefore, in this case, the first interaction determined the order and sequence of connection of atoms with each other through their structural energy flows. As a result, atoms in such a volume of space lined up in chains parallel to each other along its horizontal and vertical planes, or along planes intersecting each other at a certain acute or obtuse angle, thereby forming one and the same "geometric figure", atoms which were connected in it with each other and atoms of other similar geometric figures through structural energy flows. As a result, crystal lattices of a certain configuration were formed.

Thus, the following conclusion follows from the above: any substance is a “reified” energy structure of a certain type in a certain volume of space, consisting of: the energy connection between them - either from the structural and electromagnetic energy flows passing through the retracting and electrostatic forces of atoms of one or several types, respectively, and forming a structural and electromagnetic connection between them.

In a particular substance, depending on:

Firstly, on the magnitude of external thermal energy and the magnitude of other types of energy acting on a given substance

Secondly, from the ratio of the total amount of energy concentrated in the structural and electromagnetic energy flows of its energy structure, the latter connects atoms to each other in it either in the form of molecules or in the form of crystal lattices of a certain configuration and thereby acquires a certain state of aggregation: either an oscillating (gas ), either a vibrating (liquid) or stable (solid) state.

If the amount of external thermal energy acting on a substance, the energy structure of which consists only of structural energy flows, exceeds the total amount of thermal energy concentrated in them, then those of its structural flows that form intermolecular energy bonds expand in size. As a result, the molecules in such a substance and its energy structure acquire an oscillating state, which is commonly called the gas state. If the amount of thermal energy concentrated in those structural energy flows that form intermolecular energy bonds in the energy structure of the gas begins to decrease from them, then this causes a reduction in these structural energy flows, which first leads to the transformation of the "vibrating" state of molecules into a vibrating state (i.e. in liquid state), and then to the transformation of the vibrating state of the molecules into a stable state (i.e., into solid state).

If the energy structure of a substance consists of structural and electromagnetic energy flows and the impact appearance energy on a given substance does not cause changes in them, and the value of the energy of the first exceeds the value of the energy of the second, then with the same external types of energy constantly acting on a given substance, its state of aggregation is determined by the state of the structural energy flows of its energy structure. And vice versa, if the value of the energy of the latter exceeds the value of the energy of the former, then with the same external types of energy constantly acting on a given substance, its state of aggregation is determined by the state of the electromagnetic flows of its energy structure.

In order for the above to not be unfounded, we must prove: firstly, that the modern understanding of the main types of "chemical bonds" is not true, and secondly, that these types of bonds are actually different types of energy bonds.

All values, If he no longer believes in three words,15 express, perhaps in the most unambiguous way, the consciousness, the mentality of the Jena early Kantians. The "Critique of Pure Reason" was for them what most of all opened up space for such a belief. 2. Double definition of the boundaries of pure reason by Kant. If we raise the question about the foundations of such a difference (up to contradictions with each other) ...

And literature on this topic substantiation of the theory of pure reason by I. Kant. Objectives of the work: his transcendental doctrine of principles, transcendental doctrine of method and interpretation of the very nature of pure reason. 1. The nature of pure reason. “A strange fate has fallen to the lot of the human mind in one of its forms of knowledge: it is besieged by questions from which it cannot evade, since they are forced upon it ...

Page 1

A collection of atoms of one particular type is called a chemical element. The form of existence of chemical elements is different: they can exist in the form of simple substances in which their atoms are connected only with each other, and be part of complex substances formed by atoms of various elements.

A set of atoms that have nuclei with the same electric charge is called an element.

A collection of atoms of one kind is called a chemical element.

A group of atoms that have the same nuclear charge is called an element.

A collection of atoms held together by chemical bonds is called a molecule. Usually (though by no means always) the formation of bonds in a molecule can be explained by the existence of electron pairs, each of which links two atoms together. Such a bond formed by an electron pair is called covalent bond. Sum atomic masses of all atoms in a molecule gives its molecular weight. Although the atoms belonging to different molecules do not directly bind to each other, all molecules have some stickiness and are attracted to other molecules. These van der Waals forces of attraction cause gas molecules to stick together to form a liquid if the temperature gets low enough; under the influence of the same forces, the molecules of the liquid line up in the correct crystal lattice when the temperature of the substance decreases even more.

A group of atoms of the same type is called a chemical element. Thus, the concept of a chemical element is a collective concept.

A collection of atoms with the same charge nucleus is called a chemical element.

A group of atoms with the same positive nuclear charge is called a chemical element. Atoms are combined into molecules with the help of chemical bonds, in the formation of which valence electrons take part.

The set of atoms located in the unit cell of a crystal can be considered as a molecule, with respect to which the relations derived in the previous section are quite applicable. The elementary cell of a crystal, mentally torn out of the crystal, will scatter X-rays so all directions.

The set of atoms, molecules and other particles from which the bodies of interest to us are built, for example, semiconductor crystals, we will further call the molecular system.

A set of atoms of the same type forms an elementary, or simple, substance. Elementary substances, depending on their nature, can be divided into metallic and non-metallic. Elements that give simple substances of a metallic nature are called metallic elements (metals), and elements that give simple substances of a non-metallic nature are called non-metallic elements (non-metals), and the boundary between the two in the table of elements is the line passing through B-Si - As -Those. Of course, near this boundary there is a significant number of elements in which the properties of both metals and non-metals are found, which is manifested in the existence of allotropic modifications of the corresponding simple substances.