Parting

Name of the periodic table. What are chemical elements? System and characteristics of chemical elements

A lot of different things and objects, living and inanimate bodies of nature surround us. And they all have their own composition, structure, properties. The most complex biological processes occur in living beings. chemical reactions, accompanying life processes. Nonliving bodies perform various functions in nature and biomass life and have a complex molecular and atomic composition.

But all together the objects of the planet have common feature: They are made up of many tiny structural particles called atoms chemical elements. So small that they cannot be seen with the naked eye. What are chemical elements? What characteristics do they have and how did you know about their existence? Let's try to figure it out.

Concept of chemical elements

In the generally accepted understanding, chemical elements are just a graphical representation of atoms. The particles that make up everything that exists in the Universe. That is, the following answer can be given to the question “what are chemical elements”. These are complex small structures, collections of all isotopes of atoms, combined common name, having their own graphic designation (symbol).

To date, 118 elements are known to be discovered both naturally and synthetically, through nuclear reactions and the nuclei of other atoms. Each of them has a set of characteristics, its own location in common system, history of discovery and name, and also plays a certain role in nature and the life of living beings. The science of chemistry studies these features. Chemical elements are the basis for building molecules, simple and complex compounds, and therefore chemical interactions.

History of discovery

The very understanding of what chemical elements are came only in the 17th century thanks to the work of Boyle. It was he who first spoke about this concept and gave it the following definition. These are indivisible small simple substances from which everything around is composed, including all complex ones.

Before this work, the dominant views of alchemists were those who recognized the theory of the four elements - Empidocles and Aristotle, as well as those who discovered “combustible principles” (sulfur) and “metallic principles” (mercury).

Almost the entire 18th century, the completely erroneous theory of phlogiston was widespread. However, already at the end of this period, Antoine Laurent Lavoisier proves that it is untenable. He repeats Boyle's formulation, but at the same time supplements it with the first attempt to systematize all elements known at that time, dividing them into four groups: metals, radicals, earths, non-metals.

The next big step in understanding what chemical elements are comes from Dalton. He is credited with the discovery of atomic mass. Based on this, he distributes some of the known chemical elements in order of increasing atomic mass.

The steadily intensive development of science and technology allows us to make a number of discoveries of new elements in the composition of natural bodies. Therefore, by 1869 - the time of the great creation of D.I. Mendeleev - science became aware of the existence of 63 elements. The work of the Russian scientist became the first complete and forever established classification of these particles.

The structure of the chemical elements was not established at that time. It was believed that the atom was indivisible, that it was the smallest unit. With the discovery of the phenomenon of radioactivity, it was proven that it is divided into structural parts. Almost everyone exists in the form of several natural isotopes (similar particles, but with a different number of neutron structures, which changes atomic mass). Thus, by the middle of the last century, it was possible to achieve order in the definition of the concept of a chemical element.

Mendeleev's system of chemical elements

The scientist based it on the difference in atomic mass and managed to ingeniously arrange all the known chemical elements in increasing order. However, all the depth and genius of it scientific thinking and the foresight was that Mendeleev left empty spaces in his system, open cells for still unknown elements, which, according to the scientist, would be discovered in the future.

And everything turned out exactly as he said. Mendeleev's chemical elements filled all the empty cells over time. Every structure predicted by the scientist was discovered. And now we can safely say that the system of chemical elements is represented by 118 units. True, the last three discoveries have not yet been officially confirmed.

The system of chemical elements itself is displayed graphically in a table in which the elements are arranged according to the hierarchy of their properties, nuclear charges and structural features of the electronic shells of their atoms. So, there are periods (7 pieces) - horizontal rows, groups (8 pieces) - vertical, subgroups (main and secondary within each group). Most often, two rows of families are placed separately in the lower layers of the table - lanthanides and actinides.

The atomic mass of an element is made up of protons and neutrons, the combination of which is called the “mass number”. The number of protons is determined very simply - it is equal to the atomic number of the element in the system. And since the atom as a whole is an electrically neutral system, that is, having no charge at all, the number of negative electrons is always equal to the number of positive proton particles.

Thus, the characteristics of a chemical element can be given by its position in the periodic table. After all, almost everything is described in the cell: the serial number, which means electrons and protons, atomic mass (the average value of all existing isotopes of a given element). You can see in which period the structure is located (this means that electrons will be located on so many layers). It is also possible to predict the number of negative particles at the last energy level for elements of the main subgroups - it is equal to the number of the group in which the element is located.

The number of neutrons can be calculated by subtracting protons from the mass number, that is, the atomic number. Thus, it is possible to obtain and compile an entire electron-graphic formula for each chemical element, which will accurately reflect its structure and show the possible and manifested properties.

Distribution of elements in nature

An entire science is studying this issue - cosmochemistry. The data shows that the distribution of elements across our planet follows the same patterns in the Universe. The main source of nuclei of light, heavy and medium atoms are nuclear reactions occurring in the interior of stars - nucleosynthesis. Thanks to these processes, the Universe and outer space provided our planet with all available chemical elements.

A total of 118 known representatives in natural natural sources 89 have been discovered by humans. These are the fundamental, most common atoms. Chemical elements were also synthesized artificially by bombarding nuclei with neutrons (nucleosynthesis in laboratory conditions).

The most numerous are the simple substances of elements such as nitrogen, oxygen, and hydrogen. Carbon is included in all organic matter, which means it also occupies a leading position.

Classification according to the electronic structure of atoms

One of the most common classifications of all chemical elements of a system is their distribution based on their electronic structure. Based on how many energy levels are included in the shell of an atom and which of them contains the last valence electrons, four groups of elements can be distinguished.

S-elements

These are those in which the s-orbital is the last to be filled. This family includes elements of the first group of the main subgroup (or Just one electron at the outer level determines the similar properties of these representatives as strong reducing agents.

P-elements

Only 30 pieces. Valence electrons are located at the p-sublevel. These are the elements that form the main subgroups from the third to the eighth group, belonging to periods 3,4,5,6. Among them, the properties include both metals and typical non-metallic elements.

d-elements and f-elements

These are transition metals from the 4th to 7th major periods. There are 32 elements in total. Simple substances can exhibit both acidic and basic properties (oxidizing and reducing). Also amphoteric, that is, dual.

The f-family includes lanthanides and actinides, in which the last electrons are located in f-orbitals.

Substances formed by elements: simple

Also, all classes of chemical elements can exist in the form of simple or complex compounds. Thus, simple ones are considered to be those that are formed from the same structure in different quantities. For example, O 2 is oxygen or dioxygen, and O 3 is ozone. This phenomenon is called allotropy.

Simple chemical elements that form compounds of the same name are characteristic of each representative periodic table. But not all of them are the same in their properties. So, there are simple substances, metals and non-metals. The first form the main subgroups with 1-3 groups and all the secondary subgroups in the table. Non-metals form the main subgroups of groups 4-7. The eighth main group includes special elements - noble or inert gases.

Among all the simple elements discovered to date, 11 gases, 2 liquid substances (bromine and mercury), and all the rest are solids are known under ordinary conditions.

Complex connections

These include everything that consists of two or more chemical elements. There are a lot of examples, because chemical compounds more than 2 million are known! These are salts, oxides, bases and acids, complex compounds, all organic substances.

There are many repeating sequences in nature:

seasons;
Times of Day;
days of the week...

In the middle of the 19th century, D.I. Mendeleev noticed that chemical properties the elements also have a certain sequence (they say that this idea came to him in a dream). The result of the scientist’s wonderful dreams was the Periodic Table of Chemical Elements, in which D.I. Mendeleev arranged chemical elements in order of increasing atomic mass. In the modern table, chemical elements are arranged in ascending order of the element's atomic number (the number of protons in the nucleus of an atom).

The atomic number is shown above the symbol of a chemical element, below the symbol is its atomic mass (the sum of protons and neutrons). Please note that the atomic mass of some elements is not a whole number! Remember isotopes! Atomic mass is the weighted average of all isotopes of an element found in nature under natural conditions.

Below the table are lanthanides and actinides.

Metals, non-metals, metalloids

Located in the Periodic Table to the left of the stepped diagonal line that begins with Boron (B) and ends with polonium (Po) (the exceptions are germanium (Ge) and antimony (Sb). It is easy to see that metals occupy most of it Periodic table. Basic properties of metals: solid (except mercury); shine; good electrical and thermal conductors; plastic; malleable; give up electrons easily.

The elements located to the right of the B-Po stepped diagonal are called non-metals. The properties of non-metals are exactly the opposite of those of metals: poor conductors of heat and electricity; fragile; non-malleable; non-plastic; usually accept electrons.

Metalloids

Between metals and non-metals there are semimetals(metalloids). They are characterized by the properties of both metals and non-metals. Semimetals have found their main application in industry in the production of semiconductors, without which not a single modern microcircuit or microprocessor is conceivable.

Periods and groups

As mentioned above, the periodic table consists of seven periods. In each period, the atomic numbers of elements increase from left to right.

The properties of elements change sequentially in periods: thus sodium (Na) and magnesium (Mg), located at the beginning of the third period, give up electrons (Na gives up one electron: 1s 2 2s 2 2p 6 3s 1 ; Mg gives up two electrons: 1s 2 2s 2 2p 6 3s 2). But chlorine (Cl), located at the end of the period, takes one element: 1s 2 2s 2 2p 6 3s 2 3p 5.

In groups, on the contrary, all elements have the same properties. For example, in group IA(1), all elements from lithium (Li) to francium (Fr) donate one electron. And all elements of group VIIA(17) take one element.

Some groups are so important that they have received special names. These groups are discussed below.

Group IA(1). Atoms of elements of this group have only one electron in their outer electron layer, so they easily give up one electron.

The most important alkali metals are sodium (Na) and potassium (K), as they play important role in the process of human life and are included in the composition of salts.

Electronic configurations:

Li- 1s 2 2s 1 ;
Na- 1s 2 2s 2 2p 6 3s 1 ;
K- 1s 2 2s 2 2p 6 3s 2 3p 6 4s 1

Group IIA(2). Atoms of elements of this group have two electrons in their outer electron layer, which they also give up during chemical reactions. The most important element is calcium (Ca) - the basis of bones and teeth.

Electronic configurations:

Be- 1s 2 2s 2 ;
Mg- 1s 2 2s 2 2p 6 3s 2 ;
Ca- 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2

Group VIIA(17). Atoms of elements of this group usually receive one electron each, because There are five elements on the outer electronic layer and one electron is just missing from the “complete set”.

The most well-known elements of this group: chlorine (Cl) - is part of salt and bleach; Iodine (I) is an element that plays an important role in the activity of the human thyroid gland.

Electronic Configuration:

F- 1s 2 2s 2 2p 5 ;
Cl- 1s 2 2s 2 2p 6 3s 2 3p 5 ;
Br- 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 3d 10 4p 5

Group VIII(18). Atoms of elements of this group have a fully “complete” outer electron layer. Therefore, they “don’t” need to accept electrons. And they “don’t want” to give them away. Hence, the elements of this group are very “reluctant” to enter into chemical reactions. For a long time it was believed that they did not react at all (hence the name “inert”, i.e. “inactive”). But chemist Neil Bartlett discovered that some of these gases can still react with other elements under certain conditions.

Electronic configurations:

Ne- 1s 2 2s 2 2p 6 ;
Ar- 1s 2 2s 2 2p 6 3s 2 3p 6 ;
Kr- 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 3d 10 4p 6

Valence elements in groups

It is easy to notice that within each group the elements are similar to each other in their valence electrons (electrons of s and p orbitals located on the outer energy level).

Alkali metals have 1 valence electron:

Li- 1s 2 2s 1 ;
Na- 1s 2 2s 2 2p 6 3s 1 ;
K- 1s 2 2s 2 2p 6 3s 2 3p 6 4s 1

Alkaline earth metals have 2 valence electrons:

Be- 1s 2 2s 2 ;
Mg- 1s 2 2s 2 2p 6 3s 2 ;
Ca- 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2

Halogens have 7 valence electrons:

F- 1s 2 2s 2 2p 5 ;
Cl- 1s 2 2s 2 2p 6 3s 2 3p 5 ;
Br- 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 3d 10 4p 5

Inert gases have 8 valence electrons:

Ne- 1s 2 2s 2 2p 6 ;
Ar- 1s 2 2s 2 2p 6 3s 2 3p 6 ;
Kr- 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 3d 10 4p 6

For more information, see the article Valency and the Table of Electronic Configurations of Atoms of Chemical Elements by Period.

Let us now turn our attention to the elements located in groups with symbols IN. They are located in the center of the periodic table and are called transition metals.

A distinctive feature of these elements is the presence in the atoms of electrons that fill d-orbitals:

Sc- 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 3d 1 ;
Ti- 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 3d 2

Separately from the main table are located lanthanides And actinides- these are the so-called internal transition metals. In the atoms of these elements, electrons fill f-orbitals:

Ce- 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 3d 10 4p 6 4d 10 5s 2 5p 6 4f 1 5d 1 6s 2 ;
Th- 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 3d 10 4p 6 4d 10 5s 2 5p 6 4f 14 5d 10 6s 2 6p 6 6d 2 7s 2

Element 115 of the periodic table, moscovium, is a superheavy synthetic element with the symbol Mc and atomic number 115. It was first obtained in 2003 by a joint team of Russian and American scientists at the Joint Institute for Nuclear Research (JINR) in Dubna, Russia. In December 2015, it was recognized as one of the four new elements by the Joint Working Group of International Scientific Organizations IUPAC/IUPAP. On November 28, 2016, it was officially named in honor of the Moscow region, where JINR is located.

Characteristic

Element 115 of the periodic table is an extremely radioactive substance: its most stable known isotope, moscovium-290, has a half-life of just 0.8 seconds. Scientists classify moscovium as a non-transition metal, with a number of characteristics similar to bismuth. In the periodic table, it belongs to the transactinide elements of the p-block of the 7th period and is placed in group 15 as the heaviest pnictogen (nitrogen subgroup element), although it has not been confirmed to behave like a heavier homologue of bismuth.

According to calculations, the element has some properties similar to lighter homologues: nitrogen, phosphorus, arsenic, antimony and bismuth. At the same time, it demonstrates several significant differences from them. To date, about 100 moscovium atoms have been synthesized, which have mass numbers from 287 to 290.

Physical properties

The valence electrons of element 115 of the periodic table, moscovium, are divided into three subshells: 7s (two electrons), 7p 1/2 (two electrons), and 7p 3/2 (one electron). The first two of them are relativistically stabilized and, therefore, behave like noble gases, while the latter are relativistically destabilized and can easily participate in chemical interactions. Thus, the primary ionization potential of moscovium should be about 5.58 eV. According to calculations, moscovium should be a dense metal due to its high atomic weight with a density of about 13.5 g/cm 3 .

Estimated design characteristics:

Phase: solid.
Melting point: 400°C (670°K, 750°F).
Boiling point: 1100°C (1400°K, 2000°F).
Specific heat of fusion: 5.90-5.98 kJ/mol.
Specific heat of vaporization and condensation: 138 kJ/mol.

Chemical properties

Element 115 of the periodic table is third in the 7p series of chemical elements and is the heaviest member of group 15 in the periodic table, ranking below bismuth. Chemical interaction Muscovy in aqueous solution due to the characteristics of Mc + and Mc 3+ ions. The former are presumably easily hydrolyzed and form ionic bond with halogens, cyanides and ammonia. Muscovy(I) hydroxide (McOH), carbonate (Mc 2 CO 3), oxalate (Mc 2 C 2 O 4) and fluoride (McF) must be dissolved in water. The sulfide (Mc 2 S) must be insoluble. Chloride (McCl), bromide (McBr), iodide (McI) and thiocyanate (McSCN) are slightly soluble compounds.

Moscovium(III) fluoride (McF 3) and thiosonide (McS 3) are presumably insoluble in water (similar to the corresponding bismuth compounds). While chloride (III) (McCl 3), bromide (McBr 3) and iodide (McI 3) should be readily soluble and easily hydrolyzed to form oxohalides such as McOCl and McOBr (also similar to bismuth). Moscovium(I) and (III) oxides have similar oxidation states, and their relative stability depends largely on which elements they react with.

Uncertainty

Due to the fact that element 115 of the periodic table is synthesized experimentally in a few exact specifications problematic. Scientists have to rely on theoretical calculations and compare them with more stable elements with similar properties.

In 2011, experiments were carried out to create isotopes of nihonium, flerovium and moscovium in reactions between “accelerators” (calcium-48) and “targets” (american-243 and plutonium-244) to study their properties. However, the “targets” included impurities of lead and bismuth and, therefore, some isotopes of bismuth and polonium were obtained in nucleon transfer reactions, which complicated the experiment. Meanwhile, the data obtained will help scientists in the future study in more detail heavy homologues of bismuth and polonium, such as moscovium and livermorium.

Opening

The first successful synthesis of element 115 of the periodic table was collaboration Russian and American scientists in August 2003 at JINR in Dubna. The team led by nuclear physicist Yuri Oganesyan, in addition to domestic specialists, included colleagues from Lawrence Livermore National Laboratory. Researchers published information in the Physical Review on February 2, 2004 that they bombarded americium-243 with calcium-48 ions at the U-400 cyclotron and obtained four atoms of the new substance (one 287 Mc nucleus and three 288 Mc nuclei). These atoms decay (decay) by emitting alpha particles to the element nihonium in about 100 milliseconds. Two heavier isotopes of moscovium, 289 Mc and 290 Mc, were discovered in 2009–2010.

Initially, IUPAC could not approve the discovery of the new element. Confirmation from other sources was required. Over the next few years, the later experiments were further evaluated, and the Dubna team's claim to have discovered element 115 was once again put forward.

In August 2013, a team of researchers from Lund University and the Heavy Ion Institute in Darmstadt (Germany) announced that they had repeated the 2004 experiment, confirming the results obtained in Dubna. Further confirmation was published by a team of scientists working at Berkeley in 2015. In December 2015, a joint working group IUPAC/IUPAP recognized the discovery of this element and gave priority to the Russian-American team of researchers in the discovery.

Name

In 1979, according to the IUPAC recommendation, it was decided to name element 115 of the periodic table “ununpentium” and denote it with the corresponding symbol UUP. Although the name has since been widely used to refer to the undiscovered (but theoretically predicted) element, it has not caught on within the physics community. Most often, the substance was called that way - element No. 115 or E115.

On December 30, 2015, the discovery of a new element was recognized International Union pure and applied chemistry. According to the new rules, discoverers have the right to propose their own name for a new substance. At first it was planned to name element 115 of the periodic table “langevinium” in honor of the physicist Paul Langevin. Later, a team of scientists from Dubna, as an option, proposed the name “Moscow” in honor of the Moscow region, where the discovery was made. In June 2016, IUPAC approved the initiative and officially approved the name "moscovium" on November 28, 2016.

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MENDELEEV'S PERIODIC TABLE

The construction of Mendeleev's periodic table of chemical elements corresponds to the characteristic periods of number theory and orthogonal bases. The addition of Hadamard matrices with matrices of even and odd orders creates a structural basis of nested matrix elements: matrices of the first (Odin), second (Euler), third (Mersenne), fourth (Hadamard) and fifth (Fermat) orders.

It is easy to see that there are 4 orders k Hadamard matrices correspond to inert elements with an atomic mass that is a multiple of four: helium 4, neon 20, argon 40 (39.948), etc., but also the basics of life and digital technology: carbon 12, oxygen 16, silicon 28, germanium 72.

It seems that with Mersenne matrices of orders 4 k–1, on the contrary, everything active, poisonous, destructive and corrosive is connected. But these are also radioactive elements - energy sources, and lead 207 (the final product, poisonous salts). Fluorine, of course, is 19. The orders of the Mersenne matrices correspond to the sequence of radioactive elements called the actinium series: uranium 235, plutonium 239 (an isotope that is a more powerful source of atomic energy than uranium), etc. These are also alkali metals lithium 7, sodium 23 and potassium 39.

Gallium – atomic weight 68

Orders 4 k–2 Euler matrices (double Mersenne) correspond to nitrogen 14 (the basis of the atmosphere). Table salt is formed by two “mersenne-like” atoms of sodium 23 and chlorine 35; together this combination is characteristic of Euler matrices. The more massive chlorine with a weight of 35.4 falls just short of the Hadamard dimension of 36. Table salt crystals: a cube (! i.e. a docile character, Hadamards) and an octahedron (more defiant, this is undoubtedly Euler).

IN atomic physics transition iron 56 - nickel 59, this is the boundary between elements that provide energy during the synthesis of a larger nucleus ( hydrogen bomb) and decay (uranium). Order 58 is famous for the fact that for it there are not only no analogues of Hadamard matrices in the form of Belevich matrices with zeros on the diagonal, there are also no many weighted matrices for it - the nearest orthogonal W(58,53) has 5 zeros in each column and row (deep gap ).

In the series corresponding to the Fermat matrices and their substitutions of order 4 k+1, by the will of fate it costs Fermium 257. You can’t say anything, an exact hit. Here there is gold 197. Copper 64 (63.547) and silver 108 (107.868), symbols of electronics, do not, as can be seen, reach gold and correspond to more modest Hadamard matrices. Copper, with its atomic weight not far from 63, is chemically active - its green oxides are well known.

Boron crystals under high magnification

WITH golden ratio boron is bound - the atomic mass among all other elements is closest to 10 (more precisely 10.8, the proximity of the atomic weight to odd numbers also has an effect). Boron is a rather complex element. Boron plays an intricate role in the history of life itself. The structure of the framework in its structures is much more complex than in diamond. Unique type The chemical bond that allows boron to absorb any impurity is very poorly understood, although research related to it large number scientists have already received Nobel Prizes. The boron crystal shape is an icosahedron, with five triangles forming the apex.

The mystery of Platinum. The fifth element is, without a doubt, noble metals such as gold. Superstructure over Hadamard dimension 4 k, 1 large.

Stable isotope uranium 238

Let us remember, however, that Fermat numbers are rare (the closest is 257). Crystals of native gold have a shape close to a cube, but the pentagram also sparkles. Its nearest neighbor, platinum, a noble metal, is less than 4 atomic weight away from gold 197. Platinum has an atomic weight not 193, but a slightly higher one, 194 (the order of the Euler matrices). It's a small thing, but it brings her into the camp of somewhat more aggressive elements. It is worth remembering, in connection with its inertness (dissolves, perhaps, in aqua regia), platinum is used as an active catalyst chemical processes.

Spongy platinum ignites hydrogen at room temperature. Platinum’s character is not at all peaceful; iridium 192 (a mixture of isotopes 191 and 193) behaves more peacefully. It's more like copper, but with the weight and character of gold.

Between neon 20 and sodium 23 there is no element with atomic weight 22. Of course, the atomic weights are integral characteristic. But among the isotopes, in turn, there is also an interesting correlation of properties with the properties of numbers and the corresponding matrices of orthogonal bases. As nuclear fuel greatest application has the isotope uranium 235 (Mersenne matrix order), in which a self-sustaining chain chain is possible nuclear reaction. In nature, this element occurs in the stable form uranium 238 (Eulerian matrix order). There is no element with atomic weight 13. As for chaos, the limited number of stable elements of the periodic table and the difficulty of finding high-order level matrices due to the barrier observed in thirteenth-order matrices are correlated.

Isotopes of chemical elements, island of stability