Periodic table of Mendeleev online. Periodic law of D. I. Mendeleev and the periodic system of chemical elements

Periodic system chemical elements- This 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 long periods there 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, occupy the upper part of the periodic table. Cells occupied by elements that make up the bulk (more than 99%) of living matter are stained blue. pink color- cells occupied by trace elements (see).

The periodic system of chemical elements is biggest achievement 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 theory of the structure of the atom, it was shown that more accurate characterization 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. I period consists of two elements, the role alkali metal and 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 valence 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) Chemical properties 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.

Periodic Law D. I. Mendeleev and the system based on him 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 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. The biological activity of the 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.

On given time, officially contains 118 chemical . Of these, 94 are found in nature, the remaining 24 are obtained artificially as a result of nuclear reactions. Of all the chemicals found in nature, 88; elements such as technetium Tc, promethium Pm, astatine At and francium Fr, as well as all the elements following uranium U, were obtained artificially for the first time. IN normal conditions relevant simple substances for 11 elements they are gases, for 2 they are liquids, for the remaining elements they are solids.

Worth reading

Dmitri Ivanovich Mendeleev- Russian scientist-encyclopedist, public figure. Chemist, physical chemist, physicist, metrologist, economist, technologist, geologist, meteorologist, teacher, balloonist, instrument maker. Professor of St. Petersburg University; Corresponding member in the category of "Physics" of the Imperial St. Petersburg Academy of Sciences. Among the most famous discoveries- the periodic law of chemical elements, one of the fundamental laws of the universe, inalienable for all natural science.

Periodic system of chemical elements- classification of chemical elements, establishing the dependence of various properties of elements on the charge 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 total, several hundred variants of the image of the periodic system have been proposed. In the modern version of the system, it is supposed to reduce the elements into a two-dimensional table, in which each column determines the main physical and chemical properties, and the rows represent periods that are similar to each other to a certain extent. By the middle of the 19th century, 63 chemical elements had been discovered, and attempts to find patterns in this set were made repeatedly. More common than others are 3 forms of the periodic table: "short", "long" and "extra long". In the "extra-long" version, each period occupies exactly one line. Periodic system of D.I. Mendeleev became a milestone in the development of atomic and molecular science.

A new element has been added to the periodic table

Periodic law D.I. Mendeleev and the Periodic Table of Chemical Elements is of great importance in the development of chemistry. Let's plunge into 1871, when professor of chemistry D.I. Mendeleev, through numerous trial and error, came to the conclusion that “... the properties of the elements, and therefore the properties of the simple and complex bodies, stand in a periodic relationship with their atomic weight. The periodicity of changes in the properties of elements arises due to the periodic repetition of the electronic configuration of the outer electronic layer with an increase in the charge of the nucleus.

Modern formulation of the periodic law is:

"the properties of chemical elements (i.e., the properties and form of the compounds they form) are in a periodic dependence on the charge of the nucleus of atoms of chemical elements."

While teaching chemistry, Mendeleev understood that remembering the individual properties of each element causes difficulties for students. He began to look for ways to create system method to make it easier to remember element properties. As a result, there was natural table, later it became known as periodical.

Our modern table is very similar to Mendeleev's. Let's consider it in more detail.

Mendeleev table

The periodic table of Mendeleev consists of 8 groups and 7 periods.

The vertical columns of a table are called groups . The elements within each group have similar chemical and physical properties. This is explained by the fact that the elements of one group have similar electronic configurations of the outer layer, the number of electrons on which is equal to the group number. The group is then divided into main and secondary subgroups.

IN Main subgroups includes elements whose valence electrons are located on the outer ns- and np-sublevels. IN Side subgroups includes elements whose valence electrons are located on the outer ns-sublevel and the inner (n - 1) d-sublevel (or (n - 2) f-sublevel).

All elements in periodic table , depending on which sublevel (s-, p-, d- or f-) are valence electrons are classified into: s-elements (elements of the main subgroups I and II groups), p-elements (elements of the main subgroups III - VII groups), d- elements (elements of side subgroups), f- elements (lanthanides, actinides).

The highest valence of an element (with the exception of O, F, elements of the copper subgroup and the eighth group) is equal to the number of the group in which it is located.

For elements of the main and secondary subgroups, the formulas of higher oxides (and their hydrates) are the same. In the main subgroups, the composition of hydrogen compounds is the same for the elements in this group. Solid hydrides form elements of the main subgroups of groups I-III, and groups IV-VII form gaseous hydrogen compounds. Hydrogen compounds of the EN 4 type are more neutral compounds, EN 3 are bases, H 2 E and NE are acids.

The horizontal rows of the table are called periods. Elements in periods differ from each other, but they have in common that the last electrons are at the same energy level ( principal quantum numbern- equally ).

The first period differs from the others in that there are only 2 elements there: hydrogen H and helium He.

There are 8 elements (Li - Ne) in the second period. Lithium Li - an alkali metal begins the period, and closes its noble gas neon Ne.

In the third period, as well as in the second, there are 8 elements (Na - Ar). The alkali metal sodium Na begins the period, and the noble gas argon Ar closes it.

In the fourth period there are 18 elements (K - Kr) - Mendeleev designated it as the first large period. It also begins with the alkali metal Potassium and ends with the inert gas krypton Kr. The composition of large periods includes transition elements (Sc - Zn) - d- elements.

In the fifth period, similarly to the fourth, there are 18 elements (Rb - Xe) and its structure is similar to the fourth. It also begins with the alkali metal rubidium Rb, and ends with the inert gas xenon Xe. The composition of large periods includes transition elements (Y - Cd) - d- elements.

The sixth period consists of 32 elements (Cs - Rn). Except 10 d-elements (La, Hf - Hg) it contains a row of 14 f-elements (lanthanides) - Ce - Lu

The seventh period is not over. It starts with Francium Fr, it can be assumed that it will contain, like the sixth period, 32 elements that have already been found (up to the element with Z = 118).

Interactive periodic table

If you look at Mendeleev's periodic table and draw an imaginary line starting at boron and ending between polonium and astatine, then all metals will be to the left of the line, and non-metals to the right. Elements immediately adjacent to this line will have the properties of both metals and non-metals. They are called metalloids or semimetals. These are boron, silicon, germanium, arsenic, antimony, tellurium and polonium.

Periodic Law

Mendeleev gave the following formulation of the Periodic Law: "properties simple bodies, as well as the forms and properties of the compounds of elements, and therefore the properties of the simple and complex bodies formed by them, stand in a periodic dependence on their atomic weight.
There are four main periodic patterns:

Octet Rule states that all elements tend to gain or lose an electron in order to have the eight-electron configuration of the nearest noble gas. Because Since the outer s and p orbitals of the noble gases are completely filled, they are the most stable elements.
Ionization energy is the amount of energy required to detach an electron from an atom. According to the octet rule, moving from left to right across the periodic table requires more energy to detach an electron. Therefore, the elements on the left side of the table tend to lose an electron, and those on the right side - to gain it. Inert gases have the highest ionization energy. The ionization energy decreases as you move down the group, because electrons at low energy levels have the ability to repel electrons from higher energy levels. This phenomenon is called shielding effect. Due to this effect, the outer electrons are less strongly bound to the nucleus. Moving along the period, the ionization energy gradually increases from left to right.

electron affinity is the change in energy upon acquisition of an additional electron by an atom of a substance in a gaseous state. When moving down the group, the electron affinity becomes less negative due to the screening effect.

Electronegativity- a measure of how strongly it tends to attract the electrons of another atom bound to it. Electronegativity increases as you move periodic table left to right and bottom to top. It must be remembered that noble gases do not have electronegativity. Thus, the most electronegative element is fluorine.

Based on these concepts, let's consider how the properties of atoms and their compounds change in periodic table.

So, in a periodic dependence are such properties of an atom that are associated with its electronic configuration: atomic radius, ionization energy, electronegativity.

Consider the change in the properties of atoms and their compounds depending on the position in periodic table of chemical elements.

The non-metallicity of the atom increases when moving in the periodic table left to right and bottom to top. Due to this the basic properties of oxides decrease, A acid properties increase in the same order - when moving from left to right and from bottom to top. In this case, the acidic properties of oxides are the stronger, the more degree oxidation of its constituent element

By period from left to right basic properties hydroxides weaken, in the main subgroups from top to bottom, the strength of the bases increases. At the same time, if a metal can form several hydroxides, then with an increase in the degree of oxidation of the metal, basic properties hydroxides weaken.

By period from left to right the strength of oxygen-containing acids increases. When moving from top to bottom within the same group, the strength of oxygen-containing acids decreases. In this case, the strength of the acid increases with an increase in the degree of oxidation of the acid-forming element.

By period from left to right the strength of anoxic acids increases. When moving from top to bottom within the same group, the strength of anoxic acids increases.

Secret sections of the periodic table June 15th, 2018

Many people have heard about Dmitri Ivanovich Mendeleev and about the “Periodic law of changes in the properties of chemical elements by groups and series” discovered by him in the 19th century (1869) (the author’s name of the table is “Periodic system of elements by groups and series”).

The discovery of the table of periodic chemical elements was one of the important milestones in the history of the development of chemistry as a science. The pioneer of the table was the Russian scientist Dmitry Mendeleev. An extraordinary scientist with the broadest scientific horizons managed to combine all ideas about the nature of chemical elements into a single coherent concept.

Table opening history

By the middle of the 19th century, 63 chemical elements had been discovered, and scientists around the world have repeatedly attempted to combine all the existing elements into a single concept. Elements were proposed to be placed in ascending order atomic mass and grouped according to the similarity of chemical properties.

In 1863, the chemist and musician John Alexander Newland proposed his theory, who proposed a layout of chemical elements similar to that discovered by Mendeleev, but the work of the scientist was not taken seriously by the scientific community due to the fact that the author was carried away by the search for harmony and the connection of music with chemistry.

In 1869, Mendeleev published his scheme of the periodic table in the journal of the Russian Chemical Society and sent out a notice of the discovery to the leading scientists of the world. In the future, the chemist repeatedly refined and improved the scheme until it acquired its familiar form.

The essence of Mendeleev's discovery is that with an increase in the atomic mass, the chemical properties of elements do not change monotonously, but periodically. After a certain number of elements with different properties, the properties begin to repeat. Thus, potassium is similar to sodium, fluorine is similar to chlorine, and gold is similar to silver and copper.

In 1871, Mendeleev finally united the ideas into the Periodic Law. Scientists predicted the discovery of several new chemical elements and described their chemical properties. Subsequently, the chemist's calculations were fully confirmed - gallium, scandium and germanium fully corresponded to the properties that Mendeleev attributed to them.

But not everything is so simple and there is something we do not know.

Few people know that D. I. Mendeleev was one of the first world-famous Russian scientists of the late 19th century, who defended in world science the idea of ​​ether as a universal substantial entity, who gave it fundamental scientific and applied significance in revealing the secrets of Being and to improve the economic life of the people.

There is an opinion that the periodic table of chemical elements officially taught in schools and universities is a fake. Mendeleev himself in his work entitled "An attempt at a chemical understanding of the world ether" gave a slightly different table.

The last time, in an undistorted form, the real Periodic Table saw the light in 1906 in St. Petersburg (textbook "Fundamentals of Chemistry", VIII edition).

The differences are visible: the zero group is moved to the 8th, and the element lighter than hydrogen, with which the table should begin and which is conventionally called Newtonium (ether), is generally excluded.

The same table is immortalized by the "BLOODY TYRANT" comrade. Stalin in St. Petersburg, Moskovsky Ave. 19. VNIIM them. D. I. Mendeleeva (All-Russian Research Institute of Metrology)

The monument-table The Periodic Table of Chemical Elements of D. I. Mendeleev was made with mosaics under the guidance of Professor of the Academy of Arts V. A. Frolov (architectural design of Krichevsky). The monument is based on a table from the last lifetime 8th edition (1906) of D. I. Mendeleev’s Fundamentals of Chemistry. Elements discovered during the life of D. I. Mendeleev are marked in red. Elements discovered from 1907 to 1934 are marked in blue.

Why and how did it happen that we are so brazenly and openly lied to?

Place and role of the world ether in the true table of D. I. Mendeleev

Many people have heard about Dmitri Ivanovich Mendeleev and about the “Periodic law of changes in the properties of chemical elements by groups and series” discovered by him in the 19th century (1869) (the author’s name for the table is “The Periodic Table of Elements by Groups and Series”).

Many also heard that D.I. Mendeleev was the organizer and permanent leader (1869-1905) of the Russian public scientific association called the Russian Chemical Society (since 1872 - the Russian Physico-Chemical Society), which published the world-famous journal ZhRFKhO throughout its existence, right up to until the liquidation by the Academy of Sciences of the USSR in 1930 - both the Society and its journal.
But few of those who know that D. I. Mendeleev was one of the last world-famous Russian scientists of the late 19th century, who defended in world science the idea of ​​ether as a universal substantial entity, who gave it fundamental scientific and applied significance in revealing secrets Being and to improve the economic life of people.

Even fewer of those who know that after the sudden (!!?) death of D. I. Mendeleev (01/27/1907), who was then recognized as an outstanding scientist by all scientific communities all over the world, with the exception of the St. Petersburg Academy of Sciences alone, his main discovery - the "Periodic Law" - was deliberately and everywhere falsified by world academic science.

And there are very few who know that all of the above is linked together by the thread of sacrificial service of the best representatives and bearers of the immortal Russian Physical Thought for the good of the peoples, for public benefit, despite the growing wave of irresponsibility in the upper strata of society of that time.

In fact, comprehensive development This thesis is devoted to the last thesis, because in true science any neglect of essential factors always leads to false results.

The elements of the zero group begin each row of other elements, located on the left side of the Table, “... which is a strictly logical consequence of understanding the periodic law” - Mendeleev.

Particularly important and even exceptional in the sense of the periodic law, the place belongs to the element "x", - "Newtonius", - the world ether. And this special element should be located at the very beginning of the entire Table, in the so-called “zero group of the zero row”. Moreover, being a system-forming element (more precisely, a system-forming entity) of all elements of the Periodic Table, the world ether is a substantive argument for the entire variety of elements of the Periodic Table. The Table itself, in this regard, acts as a closed functional of this very argument.

Sources:

Few adults know how many elements are in the periodic table. Also, your knowledge may be outdated.

The fact is that the table is still in an open form, that is, it is not finished, because not all of its components are known.

If a chemist had been asked about the number of known elements at the end of the 17th century, he would have confidently said that there were 21 of them. And even when Mendeleev developed the classification of chemical elements that is used to this day (1869-1871), only 63 of them were discovered.

Attempts to systematize have been made more than once, but it is very difficult to judge the whole by its parts, and even more so to look for patterns in it.

The difficulty lay precisely in the fact that at that time scientists did not imagine that they knew only half of the links from the existing chain.

As soon as scientists and researchers tried to build the half of the table known to them. This was done not only by chemists, but also by musicians looking for a system according to the law of octaves.

Newlands almost succeeded, but he compromised himself with a mystical background, which he almost found in the chemistry of musical harmony. Only a few years after this, the table known to us was created, the number of components in which has gradually increased up to the present.

Perhaps the system in the properties of these 63 elements was discovered, according to legend, by Mendeleev in a dream, but he himself said that this did not happen suddenly, not at the snap of his fingers. In order to find patterns, he thought for almost 20 years. Moreover, they were left with empty places for the undiscovered links of this long chain.

Further expansion

By the end of the 19th century, the table was already filled with 84 elements (developing spectroscopy gave new impetus to discoveries), and by the middle of the 20th century, 13 more were added. Therefore, schoolchildren in 1950 could confidently declare that there were 97 components in the periodic table.

Mendeleev table.

Since then, items numbered from 98 have been gradually opened and expanded the table after the start of use. atomic energy. So, in 2011, the 114th and 116th cells were already filled.

At the beginning of 2016, the table was replenished again - 4 new elements were added to it, although they were discovered much earlier.

Their atomic numbers are 113, 115, 117 and 118, and one of the chemical elements of Japanese origin (working name ununtrium, or abbreviated as Uut). This discovery finally allowed the chemists of Japan, along with others, to get into the periodic table, placing their discovery in the 113th cell.

The remaining elements were discovered by the Russian-American group:

• ununpentium, or Uup (115);
• ununseptium, or Uus (117);
• ununoctium, or Uuo (118).

These are temporary names, and in the second half of 2016 their real names and abbreviations of 2 letters will appear in the table. The right to choose names belongs to the discoverers. Where they will end up is still unknown.

The names may be related to mythology, astronomy, geography, or they may be terms from chemistry, or maybe the names of scientists.

How many are there?

Even if you know exactly how many elements are contained in the periodic table, you can answer in two ways, and both answers will be correct.

The fact is that this table has two versions. One contains 118 components, and the second contains 126.

The difference between them is that in the first version, the components are already open and officially accepted by the scientific community, and in the second, hypothetical ones are also included, that is, they exist only on paper and in the minds of scientists. They can be obtained tomorrow, or maybe in 100 years.

But in the 118-element version, all components really exist. Of these, 94 were found in nature, the rest were obtained in the laboratory. Nevertheless, the second option also has the right to exist, because nature loves order.

If the pattern shows that the existing chemical elements should have a continuation, then sooner or later it will appear thanks to new, yet unknown technologies.