How to use the periodic table? For an uninitiated person, reading the periodic table is the same as looking at the ancient runes of elves for a dwarf. And the periodic table can tell a lot about the world.

In addition to serving you in the exam, it is also simply indispensable for solving a huge number of chemical and physical problems. But how to read it? Fortunately, today everyone can learn this art. In this article we will tell you how to understand the periodic table.

The periodic system of chemical elements (Mendeleev's table) is a classification of chemical elements that establishes the dependence of various properties of elements on the charge of the atomic nucleus.

History of the creation of the Table

Dmitri Ivanovich Mendeleev was not a simple chemist, if someone thinks so. He was a chemist, physicist, geologist, metrologist, ecologist, economist, oilman, aeronaut, instrument maker and teacher. During his life, the scientist managed to conduct a lot of fundamental research in various fields of knowledge. For example, it is widely believed that it was Mendeleev who calculated the ideal strength of vodka - 40 degrees.

We do not know how Mendeleev treated vodka, but it is known for sure that his dissertation on the topic “Discourse on the combination of alcohol with water” had nothing to do with vodka and considered alcohol concentrations from 70 degrees. With all the merits of the scientist, the discovery of the periodic law of chemical elements - one of the fundamental laws of nature, brought him the widest fame.

There is a legend according to which the scientist dreamed of the periodic system, after which he only had to finalize the idea that had appeared. But, if everything were so simple .. This version of the creation of the periodic table, apparently, is nothing more than a legend. When asked how the table was opened, Dmitry Ivanovich himself answered: “ I’ve been thinking about it for maybe twenty years, and you think: I sat and suddenly ... it’s ready. ”

In the middle of the nineteenth century, attempts to streamline the known chemical elements (63 elements were known) were simultaneously undertaken by several scientists. For example, in 1862 Alexandre Émile Chancourtois placed the elements along a helix and noted the cyclical repetition of chemical properties.

Chemist and musician John Alexander Newlands proposed his own version periodic table in 1866. An interesting fact is that in the arrangement of the elements the scientist tried to discover some mystical musical harmony. Among other attempts was the attempt of Mendeleev, which was crowned with success.

In 1869, the first scheme of the table was published, and the day of March 1, 1869 is considered the day of the discovery of the periodic law. The essence of Mendeleev's discovery was that the properties of elements with increasing atomic mass do not change monotonously, but periodically.

The first version of the table contained only 63 elements, but Mendeleev undertook a number of very non-standard solutions. So, he guessed to leave a place in the table for yet undiscovered elements, and also changed the atomic masses of some elements. The fundamental correctness of the law derived by Mendeleev was confirmed very soon after the discovery of gallium, scandium and germanium, the existence of which was predicted by scientists.

Modern view of the periodic table

Below is the table itself.

Today, instead of atomic weight (atomic mass), the concept of atomic number (the number of protons in the nucleus) is used to order elements. The table contains 120 elements, which are arranged from left to right in ascending order of atomic number (number of protons)

The columns of the table are so-called groups, and the rows are periods. There are 18 groups and 8 periods in the table.

1. The metallic properties of elements decrease when moving along the period from left to right, and increase in the opposite direction.
2. The dimensions of atoms decrease as they move from left to right along the periods.
3. When moving from top to bottom in the group, the reducing metallic properties increase.
4. Oxidizing and non-metallic properties increase along the period from left to right.

What do we learn about the element from the table? For example, let's take the third element in the table - lithium, and consider it in detail.

First of all, we see the symbol of the element itself and its name under it. In the upper left corner is the atomic number of the element, in the order in which the element is located in the table. The atomic number, as already mentioned, is equal to the number of protons in the nucleus. The number of positive protons is usually equal to the number of negative electrons in an atom (with the exception of isotopes).

Atomic mass is listed under atomic number (in this option tables). If we round the atomic mass to the nearest integer, we get the so-called mass number. The difference between the mass number and the atomic number gives the number of neutrons in the nucleus. Thus, the number of neutrons in a helium nucleus is two, and in lithium - four.

So our course "Mendeleev's Table for Dummies" has ended. In conclusion, we invite you to watch a thematic video, and we hope that the question of how to use the periodic table of Mendeleev has become more clear to you. We remind you that learning a new subject is always more effective not alone, but with the help of an experienced mentor. That is why, you should never forget about, who will gladly share his knowledge and experience with you.

Periodic system of chemical elements (Mendeleev's table)- classification of chemical elements, establishing the dependence of various properties of elements on the charge of the atomic nucleus. The system is a graphical expression of the periodic law established by the Russian chemist D. I. Mendeleev in 1869. Its original version was developed by D. I. Mendeleev in 1869-1871 and established the dependence of the properties of elements on their atomic weight (in modern terms, on atomic mass). In total, several hundred variants of the representation of the periodic system (analytical curves, tables, geometric figures, etc.) have been proposed. AT modern version system, it is supposed to reduce the elements into a two-dimensional table, in which each column (group) determines the main physical Chemical properties, and the lines represent periods that are somewhat similar to each other.

Periodic system of chemical elements of D.I. Mendeleev

The discovery made by the Russian chemist Mendeleev played (by far) the most important role in the development of science, namely in the development of atomic and molecular science. This discovery made it possible to obtain the most understandable and easy-to-learn ideas about simple and complex chemical compounds. Only thanks to the table we have those concepts about the elements that we use in modern world. In the twentieth century, the predictive role of the periodic system in assessing the chemical properties of transuranium elements, shown by the creator of the table, manifested itself.

Developed in the 19th century, Mendeleev's periodic table in the interests of the science of chemistry, gave a ready-made systematization of the types of atoms for the development of PHYSICS in the 20th century (physics of the atom and the nucleus of the atom). At the beginning of the twentieth century, physicists, through research, established that the serial number, (aka atomic), is also a measure of the electric charge of the atomic nucleus of this element. And the number of the period (ie the horizontal row) determines the number of electron shells of the atom. It also turned out that the number of the vertical row of the table determines the quantum structure of the outer shell of the element (thus, the elements of the same row are due to the similarity of chemical properties).

The discovery of the Russian scientist, marked itself, new era in the history of world science, this discovery allowed not only to make a huge leap in chemistry, but was also invaluable for a number of other areas of science. The periodic table gave a coherent system of information about the elements, based on it, it became possible to draw scientific conclusions, and even foresee some discoveries.

Periodic table One of the features of the periodic table of the Mendeleev is that the group (column in the table) has more significant expressions of the periodic trend than for periods or blocks. Nowadays, the theory of quantum mechanics and atomic structure explains the group nature of elements by the fact that they have the same electronic configurations of valence shells, and as a result, elements that are within the same column have very similar (identical) features of the electronic configuration, with similar chemical properties. There is also a clear trend of a stable change in properties as the atomic mass increases. It should be noted that in some areas of the periodic table (for example, in blocks D and F), horizontal similarities are more noticeable than vertical ones.

The periodic table contains groups that are assigned serial numbers from 1 to 18 (from left to right), according to the international group naming system. In the old days, Roman numerals were used to identify groups. In America, the practice was to put after the Roman numeral, the letter "A" when the group is located in blocks S and P, or the letters "B" - for groups located in block D. The identifiers used at that time are the same as the last the number of modern pointers in our time (for example, the name IVB, corresponds to the elements of the 4th group in our time, and IVA is the 14th group of elements). In European countries of that time, a similar system was used, but here, the letter "A" referred to groups up to 10, and the letter "B" - after 10 inclusive. But groups 8,9,10 had the identifier VIII as one triple group. These group names ceased to exist after the new IUPAC notation system, which is still in use today, came into force in 1988.

Many groups have received non-systematic names of a traditional nature (for example, "alkaline earth metals", or "halogens", and other similar names). Groups 3 to 14 did not receive such names, due to the fact that they are less similar to each other and have less correspondence to vertical patterns, they are usually called either by number or by the name of the first element of the group (titanium, cobalt, etc.) .

Chemical elements belonging to the same group of the periodic table show certain trends in electronegativity, atomic radius and ionization energy. In one group, from top to bottom, the radius of the atom increases, as the energy levels are filled, the valence electrons of the element are removed from the nucleus, while the ionization energy decreases and the bonds in the atom weaken, which simplifies the removal of electrons. The electronegativity also decreases, this is a consequence of the fact that the distance between the nucleus and the valence electrons increases. But there are also exceptions to these patterns, for example, electronegativity increases, instead of decreasing, in group 11, from top to bottom. In the periodic table there is a line called "Period".

Among groups, there are those in which horizontal directions are more significant (unlike others, in which greater value have vertical directions), such groups include block F, in which the lanthanides and actinides form two important horizontal sequences.

The elements show certain patterns in terms of atomic radius, electronegativity, ionization energy, and electron affinity energy. Due to the fact that for each next element the number of charged particles increases, and electrons are attracted to the nucleus, the atomic radius decreases in the direction from left to right, along with this, the ionization energy increases, with an increase in the bond in the atom, the difficulty of removing an electron increases. Metals located on the left side of the table are characterized by a lower electron affinity energy indicator, and accordingly, on the right side, the electron affinity energy indicator, for non-metals, this indicator is higher (not counting noble gases).

Different areas of the periodic table of Mendeleev, depending on which shell of the atom the last electron is on, and in view of the significance of the electron shell, it is customary to describe it as blocks.

The S-block includes the first two groups of elements, (alkali and alkaline earth metals, hydrogen and helium).
The P-block includes the last six groups, from 13 to 18 (according to IUPAC, or according to the system adopted in America - from IIIA to VIIIA), this block also includes all metalloids.

Block - D, groups 3 to 12 (IUPAC, or IIIB to IIB in American), this block includes all transition metals.
Block - F, usually taken out of the periodic table, and includes lanthanides and actinides.

The periodic law was discovered by D.I. Mendeleev while working on the text of the textbook "Fundamentals of Chemistry", when he encountered difficulties in systematizing the factual material. By mid-February 1869, thinking over the structure of the textbook, the scientist gradually came to the conclusion that the properties of simple substances and the atomic masses of elements are connected by a certain regularity.

The discovery of the periodic table of elements was not made by chance, it was the result of a huge work, long and painstaking work, which was spent both by Dmitry Ivanovich himself and by many chemists from among his predecessors and contemporaries. “When I began to finalize my classification of the elements, I wrote on separate cards each element and its compounds, and then, arranging them in the order of groups and rows, I received the first visual table of the periodic law. But this was only the final chord, the result of all previous work ... "- said the scientist. Mendeleev emphasized that his discovery was the result that completed twenty years of thinking about the relationships between elements, thinking from all sides of the relationship of elements.

On February 17 (March 1), the manuscript of the article, containing a table entitled "An experiment on a system of elements based on their atomic weight and chemical similarity," was completed and submitted for printing with notes for compositors and with the date "February 17, 1869." The report on the discovery of Mendeleev was made by the editor of the Russian Chemical Society, Professor N.A. Menshutkin at a meeting of the society on February 22 (March 6), 1869. Mendeleev himself was not present at the meeting, since at that time, on the instructions of the Free Economic Society, he examined the cheese factories of the Tver and Novgorod provinces.

In the first version of the system, the elements were arranged by scientists in nineteen horizontal rows and six vertical columns. On February 17 (March 1), the discovery of the periodic law was by no means completed, but only began. Dmitry Ivanovich continued its development and deepening for almost three more years. In 1870, Mendeleev published the second version of the system (The Natural System of Elements) in Fundamentals of Chemistry: horizontal columns of analogous elements turned into eight vertically arranged groups; the six vertical columns of the first version turned into periods beginning with an alkali metal and ending with a halogen. Each period was divided into two rows; elements of different rows included in the group formed subgroups.

The essence of Mendeleev's discovery was that with an increase in the atomic mass of chemical elements, their properties do not change monotonously, but periodically. After a certain number of elements of different properties, arranged in ascending atomic weight, the properties begin to repeat. The difference between Mendeleev's work and the works of his predecessors was that Mendeleev had not one, but two bases for classifying elements - atomic mass and chemical similarity. In order for the periodicity to be fully respected, Mendeleev corrected the atomic masses of some elements, placed several elements in his system contrary to the then accepted ideas about their similarity with others, left empty cells in the table where elements that were not yet discovered should have been placed.

In 1871, on the basis of these works, Mendeleev formulated the Periodic Law, the form of which was somewhat improved over time.

The Periodic Table of the Elements had a great influence on the subsequent development of chemistry. Not only was it the first natural classification of the chemical elements, which showed that they form a coherent system and are in close connection with each other, but it was also a powerful tool for further research. At the time when Mendeleev compiled his table on the basis of the periodic law discovered by him, many elements were not yet known. Over the next 15 years, Mendeleev's predictions were brilliantly confirmed; all three expected elements were discovered (Ga, Sc, Ge), which was the greatest triumph of the periodic law.

ARTICLE "MENDELEEV"

Mendeleev (Dmitry Ivanovich) - prof., b. in Tobolsk, January 27, 1834). His father, Ivan Pavlovich, director of the Tobolsk gymnasium, soon became blind and died. Mendeleev, a ten-year-old boy, remained in the care of his mother, Maria Dmitrievna, nee Kornilyeva, a woman of an outstanding mind and enjoyed general respect in the local intelligentsia society. M.'s childhood and high school years are spent in an environment conducive to the formation of an original and independent character: her mother was a supporter of the free awakening of her natural vocation. Love for reading and studying was clearly expressed in M. only at the end of the gymnasium course, when the mother, deciding to send her son to science, took him as a 15-year-old boy from Siberia, first to Moscow, and then a year later to St. Petersburg, where she was placed in pedagogical institute ... A real, all-consuming study of all branches of positive science began at the institute ... At the end of the course at the institute, due to poor health, he left for the Crimea and was assigned as a gymnasium teacher, first in Simferopol, then in Odessa. But already in 1856. he again returned to St. Petersburg, entered as a Privatdozent in St. Petersburg. univ. and defended his dissertation "On specific volumes", for a master's degree in chemistry and physics ... In 1859, M. was sent abroad ... In 1861, M. again became a privatdozent in St. Petersburg. university. Soon after, he published the course "Organic Chemistry" and the article "On the Limit of СnН2n+ Hydrocarbons". In 1863, Mr.. M. was appointed professor of St. Petersburg. Technological Institute and for several years dealt with technical issues a lot: he traveled to the Caucasus to study oil near Baku, made agricultural experiments Imp. Free Economic Society, published technical manuals, etc. In 1865, he studied alcohol solutions according to their specific gravity, which served as the subject of his doctoral dissertation, which he defended the following year. Professor of St. Petersburg. univ. in the Department of Chemistry, M. was elected and appointed in 1866. Since then, his scientific activity has taken on such dimensions and diversity that in a brief essay it is possible to point out only the most important works. In 1868 - 1870. he writes his Fundamentals of Chemistry, where for the first time the principle of his periodic system of elements is carried out, which made it possible to foresee the existence of new, yet undiscovered elements and to accurately predict the properties of both themselves and their various compounds. In 1871 - 1875. engaged in the study of elasticity and expansion of gases and publishes his essay "On the elasticity of gases". In 1876, on behalf of the government, he went to Pennsylvania to inspect American oil fields and then several times to the Caucasus to study the economic conditions of oil production and the conditions for oil production, which led to the widespread development of the oil industry in Russia; he himself is engaged in the study of petroleum hydrocarbons, publishes several essays about everything and analyzes the issue of the origin of oil in them. Around the same time, he dealt with issues related to aeronautics and the resistance of liquids, accompanying his studies with the publication of separate works. In the 80s. he again turns to the study of solutions, which resulted in Op. "Investigation of aqueous solutions by specific gravity", the conclusions of which found so many followers among chemists of all countries. In 1887, during a total solar eclipse, he rises alone in a balloon in Klin, himself makes a risky adjustment of the valves, makes the ball obedient and enters into the annals of this phenomenon everything that he managed to notice. In 1888, he studied the economic conditions of the Donetsk coal region on the spot. In 1890, Mr.. M. stopped reading his course in inorganic chemistry in St. Petersburg. university. Other extensive economic and state tasks from that time began to especially occupy him. Appointed as a member of the Council of Trade and Manufactories, he takes an active part in the development and systematic implementation of a tariff that is patronizing for the Russian manufacturing industry and publishes the essay "Explanatory Tariff of 1890", interpreting in all respects why Russia needed such patronage. At the same time, he was involved by the military and naval ministries in the question of re-equipping the Russian army and navy to develop a type of smokeless powder, and after a trip to England and France, which then already had their own gunpowder, he was appointed in 1891 as a consultant to the manager of the naval ministry on powder issues and, working together with employees (his former students) in the scientific and technical laboratory of the naval department, opened specifically for the purpose of studying the aforementioned issue, already at the very beginning of 1892 he indicated the required type of smokeless powder, called pyrocollodic, universal and easily adaptable to any firearms. With the opening of the Chamber of Weights and Measures in the Ministry of Finance, in 1893, it is determined in it by the scientific custodian of measures and weights and begins the publication of the Vremennik, in which all measurement studies carried out in the chamber are published. Sensitive and responsive to all scientific issues of paramount importance, M. was also keenly interested in other phenomena of current Russian social life, and wherever possible, he said his word ... Since 1880, he began to be interested in the art world, especially Russian, collects art collections and etc., and in 1894 he was elected a full member of the Imperial Academy of Arts ... The various scientific issues of paramount importance that were the subject of M.'s study, due to their multiplicity, cannot be listed here. He wrote up to 140 works, articles and books. But time to evaluate historical significance these works have not yet come, and M., we hope, will not stop researching and expressing his powerful word on newly emerging issues, both science and life, for a long time to come ...

RUSSIAN CHEMICAL SOCIETY

The Russian Chemical Society is a scientific organization founded at St. Petersburg University in 1868 and was a voluntary association of Russian chemists.

The need to create the Society was announced at the 1st Congress of Russian Naturalists and Doctors, held in St. Petersburg in late December 1867 - early January 1868. At the Congress, the decision of the participants in the Chemical Section was announced:

The Chemistry Section declared a unanimous desire to unite in the Chemical Society for the communication of the already established forces of Russian chemists. The section believes that this society will have members in all cities of Russia, and that its publication will include the works of all Russian chemists, printed in Russian.

By this time, chemical societies had already been established in several European countries: the London Chemical Society (1841), the Chemical Society of France (1857), the German Chemical Society (1867); The American Chemical Society was founded in 1876.

The Charter of the Russian Chemical Society, compiled mainly by D.I. Mendeleev, was approved by the Ministry of Public Education on October 26, 1868, and the first meeting of the Society was held on November 6, 1868. Initially, it included 35 chemists from St. Petersburg, Kazan, Moscow, Warsaw, Kyiv, Kharkov and Odessa. In the first year of its existence, the RCS grew from 35 to 60 members and continued to grow smoothly in subsequent years (129 in 1879, 237 in 1889, 293 in 1899, 364 in 1909, 565 in in 1917).

In 1869, the Russian Chemical Society got its own printed organ - the Journal of the Russian Chemical Society (ZhRHO); the magazine was published 9 times a year (monthly, except for the summer months).

In 1878, the RCS merged with the Russian Physical Society (founded in 1872) to form the Russian Physical and Chemical Society. The first Presidents of RFHO were A.M. Butlerov (in 1878-1882) and D.I. Mendeleev (in 1883-1887). In connection with the merger, in 1879 (from the 11th volume) the Journal of the Russian Chemical Society was renamed into the Journal of the Russian Physical and Chemical Society. The periodicity of the publication was 10 issues per year; The journal consisted of two parts - chemical (ZhRHO) and physical (ZhRFO).

For the first time, many works of the classics of Russian chemistry were published on the pages of the ZhRHO. The works of D.I. Mendeleev on the creation and development of the periodic system of elements and A.M. Butlerov, connected with the development of his theory of the structure of organic compounds ... During the period from 1869 to 1930, 5067 original chemical studies were published in the ZhRHO, abstracts and review articles on certain issues of chemistry, translations of the most interesting works from foreign journals were also published.

RFHO became the founder of the Mendeleev Congresses on General and Applied Chemistry; the first three congresses were held in St. Petersburg in 1907, 1911 and 1922. In 1919, the publication of the ZhRFKhO was suspended and resumed only in 1924.

The periodic system of chemical elements is a classification of chemical elements created by D. I. Mendeleev on the basis of the periodic law discovered by him in 1869.

D. I. Mendeleev

According to the modern formulation of this law, in a continuous series of elements arranged in ascending order of the positive charge of the nuclei of their atoms, elements with similar properties are periodically repeated.

The periodic system of chemical elements, presented in the form of a table, consists of periods, series and groups.

At the beginning of each period (with the exception of the first) there is an element with pronounced metallic properties (alkali metal).

Symbols for the color table: 1 - chemical sign of the element; 2 - name; 3 - atomic mass (atomic weight); 4 - serial number; 5 - distribution of electrons over the layers.

As the ordinal number of the element increases, equal to the value of the positive charge of the nucleus of its atom, the metallic properties gradually weaken and the non-metallic properties increase. The penultimate element in each period is an element with pronounced non-metallic properties (), and the last is an inert gas. In period I there are 2 elements, in II and III - 8 elements each, in IV and V - 18 elements each, in VI - 32 and in VII (incomplete period) - 17 elements.

The first three periods are called small periods, each of them consists of one horizontal row; the rest - in large periods, each of which (excluding the VII period) consists of two horizontal rows - even (upper) and odd (lower). In even rows of large periods are only metals. The properties of the elements in these rows change slightly with increasing serial number. The properties of elements in odd series of large periods change. In period VI, lanthanum is followed by 14 elements that are very similar in chemical properties. These elements, called lanthanides, are listed separately under the main table. Actinides, the elements following actinium, are similarly presented in the table.

The table has nine vertical groups. The group number, with rare exceptions, is equal to the highest positive valence of the elements of this group. Each group, excluding zero and eighth, is divided into subgroups. - main (located to the right) and side. In the main subgroups, with an increase in the serial number, the metallic properties of the elements are enhanced and the non-metallic properties of the elements are weakened.

Thus, the chemical and a number of physical properties of elements are determined by the place that a given element occupies in the periodic system.

Biogenic elements, i.e., elements that make up organisms and perform a certain biological role in it, occupy the upper part of the periodic table. The cells occupied by the elements that make up the bulk (more than 99%) of living matter are colored blue, the cells occupied by microelements are colored pink (see).

The periodic system of chemical elements is the greatest achievement of modern natural science and a vivid expression of the most general dialectical laws of nature.

See also , Atomic weight.

The periodic system of chemical elements is a natural classification of chemical elements created by D. I. Mendeleev on the basis of the periodic law discovered by him in 1869.

In the original formulation, the periodic law of D. I. Mendeleev stated: the properties of chemical elements, as well as the forms and properties of their compounds, are in a periodic dependence on the magnitude of the atomic weights of the elements. Later, with the development of the doctrine of the structure of the atom, it was shown that a more accurate characteristic of each element is not the atomic weight (see), but the value of the positive charge of the nucleus of the atom of the element, equal to the ordinal (atomic) number of this element in the periodic system of D. I. Mendeleev . The number of positive charges on the nucleus of an atom is equal to the number of electrons surrounding the nucleus of an atom, since atoms as a whole are electrically neutral. In the light of these data, the periodic law is formulated as follows: the properties of chemical elements, as well as the forms and properties of their compounds, are in a periodic dependence on the positive charge of the nuclei of their atoms. This means that in a continuous series of elements, arranged in ascending order of the positive charges of the nuclei of their atoms, elements with similar properties will be periodically repeated.

The tabular form of the periodic system of chemical elements is presented in its modern form. It consists of periods, series and groups. A period represents a sequential horizontal row of elements arranged in ascending order of the positive charge of the nuclei of their atoms.

At the beginning of each period (with the exception of the first) there is an element with pronounced metallic properties (alkali metal). Then, as the serial number increases, the metallic properties of the elements gradually weaken and the non-metallic properties of the elements increase. The penultimate element in each period is an element with pronounced non-metallic properties (halogen), and the last is an inert gas. Period I consists of two elements, the role of an alkali metal and a halogen is simultaneously performed by hydrogen. II and III periods include 8 elements each, called Mendeleev typical. IV and V periods have 18 elements each, VI-32. VII period is not yet completed and is replenished with artificially created elements; there are currently 17 elements in this period. I, II and III periods are called small, each of them consists of one horizontal row, IV-VII - large: they (with the exception of VII) include two horizontal rows - even (upper) and odd (lower). In even rows of large periods, only metals are found, and the change in the properties of the elements in the row from left to right is weakly expressed.

In odd series of large periods, the properties of the elements in the series change in the same way as the properties of typical elements. In an even number of the VI period after lanthanum 14 elements follow [called lanthanides (see), lanthanides, rare earth elements], similar in chemical properties to lanthanum and to each other. Their list is given separately under the table.

Separately, the elements following the actinium-actinides (actinides) are written out and given under the table.

There are nine vertical groups in the periodic table of chemical elements. The group number is equal to the highest positive valency (see) of the elements of this group. The exceptions are fluorine (it happens only negatively monovalent) and bromine (it does not happen heptavalent); in addition, copper, silver, gold can exhibit a valence greater than +1 (Cu-1 and 2, Ag and Au-1 and 3), and of the elements of group VIII, only osmium and ruthenium have a valency of +8. Each group, with the exception of the eighth and zero, is divided into two subgroups: the main (located to the right) and the secondary. The main subgroups include typical elements and elements of large periods, the secondary - only elements of large periods and, moreover, metals.

In terms of chemical properties, the elements of each subgroup of this group differ significantly from each other, and only the highest positive valency is the same for all elements of this group. In the main subgroups, from top to bottom, the metallic properties of elements increase and non-metallic ones weaken (for example, francium is an element with the most pronounced metallic properties, and fluorine is non-metallic). Thus, the place of an element in the periodic system of Mendeleev (serial number) determines its properties, which are the average of the properties of neighboring elements vertically and horizontally.

Some groups of elements have special names. So, the elements of the main subgroups of group I are called alkali metals, group II - alkaline earth metals, group VII - halogens, elements located behind uranium - transuranium. Elements that are part of organisms, take part in metabolic processes and have a pronounced biological role, are called biogenic elements. All of them occupy the upper part of the table of D. I. Mendeleev. This is primarily O, C, H, N, Ca, P, K, S, Na, Cl, Mg and Fe, which make up the bulk of living matter (more than 99%). The places occupied by these elements in the periodic table are colored in light blue. Biogenic elements, which are very few in the body (from 10 -3 to 10 -14%), are called microelements (see). In the cells of the periodic system, colored yellow, microelements are placed, the vital importance of which for humans has been proven.

According to the theory of the structure of atoms (see Atom), the chemical properties of elements depend mainly on the number of electrons in the outer electron shell. The periodic change in the properties of elements with an increase in the positive charge of atomic nuclei is explained by the periodic repetition of the structure of the outer electron shell (energy level) of atoms.

In small periods, with an increase in the positive charge of the nucleus, the number of electrons in the outer shell increases from 1 to 2 in period I and from 1 to 8 in periods II and III. Hence the change in the properties of the elements in the period from an alkali metal to an inert gas. The outer electron shell, containing 8 electrons, is complete and energetically stable (elements of the zero group are chemically inert).

In large periods in even rows, with an increase in the positive charge of the nuclei, the number of electrons in the outer shell remains constant (1 or 2) and the second outer shell is filled with electrons. Hence the slow change in the properties of elements in even rows. In odd series of long periods, with an increase in the charge of the nuclei, the outer shell is filled with electrons (from 1 to 8) and the properties of the elements change in the same way as for typical elements.

The number of electron shells in an atom is equal to the period number. The atoms of the elements of the main subgroups have a number of electrons on their outer shells equal to the group number. The atoms of the elements of the secondary subgroups contain one or two electrons on the outer shells. This explains the difference in the properties of the elements of the main and secondary subgroups. The group number indicates the possible number of electrons that can participate in the formation of chemical (valence) bonds (see Molecule), therefore such electrons are called valence. For elements of secondary subgroups, not only the electrons of the outer shells, but also the penultimate ones, are valence. The number and structure of electron shells are indicated in the attached periodic table of chemical elements.

The periodic law of D. I. Mendeleev and the system based on it have exclusively great importance in science and practice. The periodic law and the system were the basis for the discovery of new chemical elements, the accurate determination of their atomic weights, the development of the theory of the structure of atoms, the establishment of geochemical laws for the distribution of elements in the earth's crust and the development of modern ideas about living matter, the composition of which and the laws associated with it are in accordance with the periodic system. Biological activity elements and their content in the body are also largely determined by the place they occupy in the periodic system of Mendeleev. So, with an increase in the serial number in a number of groups, the toxicity of elements increases and their content in the body decreases. The periodic law is a vivid expression of the most general dialectical laws of the development of nature.

Four ways to attach nucleons
Nucleon attachment mechanisms can be divided into four types, S, P, D and F. These types of attachment reflect the color background in our version of the D.I. table. Mendeleev.
The first type of attachment is the S scheme, when nucleons are attached to the nucleus along the vertical axis. The display of attached nucleons of this type, in the internuclear space, is now identified as S electrons, although there are no S electrons in this zone, but there are only spherical regions of the volume space charge that provide molecular interaction.
The second type of attachment is the P scheme, when nucleons are attached to the nucleus in the horizontal plane. The mapping of these nucleons in the internuclear space is identified as P electrons, although these, too, are just regions of space charge generated by the nucleus in the internuclear space.
The third type of attachment is the D scheme, when nucleons attach to neutrons in the horizontal plane, and finally, the fourth type of attachment is the F scheme, when nucleons attach to neutrons along the vertical axis. Each type of attachment gives the atom the properties characteristic of this type of bond, therefore, in the composition of the periods of the D.I. Mendeleev has long identified subgroups, according to the type of S, P, D and F bonds.
Since the addition of each subsequent nucleon produces an isotope of either the preceding or subsequent element, the exact arrangement of nucleons according to the type S, P, D and F bonds can only be shown using the Table of known isotopes (nuclides), a version of which (from Wikipedia) we used.
We divided this table into periods (see Tables of filling periods), and in each period we indicated the scheme by which each nucleon joins. Since, in accordance with the microquantum theory, each nucleon can join the nucleus only in a strictly defined place, the number and schemes of nucleon attachment in each period are different, but in all periods of the D.I. Mendeleev's laws of nucleon addition are performed uniformly for all nucleons without exception.
As you can see, in periods II and III, nucleons are added only according to S and P schemes, in periods IV and V - according to S, P and D schemes, and in periods VI and VII - according to S, P, D and F schemes. At the same time, it turned out that the laws of nucleon addition are executed so accurately that it was not difficult for us to calculate the composition of the nucleus of finite elements of the VII period, which in the table of D.I. Mendeleev have numbers 113, 114, 115, 116 and 118.
According to our calculations, the last element of period VII, which we called Rs (“Russia” from “Russia”), consists of 314 nucleons and has isotopes 314, 315, 316, 317 and 318. The element preceding it is Nr (“Novorossiya” from “ Novorossiya) consists of 313 nucleons. We will be very grateful to anyone who can confirm or refute our calculations.
To be honest, we ourselves are amazed at how accurately the Universal Constructor works, which ensures that each subsequent nucleon is attached only to its only correct place, and if the nucleon is placed incorrectly, the Constructor ensures the disintegration of the atom, and assembles a new atom from its parts. In our films, we have shown only the main laws of the work of the Universal Constructor, but there are so many nuances in his work that it will take the efforts of many generations of scientists to understand them.
But it is necessary for humanity to understand the laws of the work of the Universal Designer if it is interested in technological progress, since knowledge of the principles of the work of the Universal Designer opens up completely new perspectives in all areas of human activity - from the creation of unique structural materials to the assembly of living organisms.

Filling in the second period of the table of chemical elements

Filling in the third period of the table of chemical elements

Filling in the fourth period of the table of chemical elements

Filling in the fifth period of the table of chemical elements

Filling in the sixth period of the table of chemical elements

Filling in the seventh period of the table of chemical elements

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