V table element. What are chemical elements? System and characteristics of chemical elements. The concept of chemical elements

There are a lot of different things and items, living and non-residential bodies of nature. And they all have their own structure, structure, properties. In living beings, the most complex biochemical reactions accompanying the processes of vital activity proceed. Non-fat bodies perform various functions in the nature and life of biomass and have a complex molecular and atomic composition.

But all together, the objects of the planet have a common feature: they consist of a variety of smallest structural particles, called atoms of chemical elements. So small that they did not consider them with a naked eye. What are chemical elements? What characteristics do they have and where did they know about their existence? Let's try to figure out.

The concept of chemical elements

In the generally accepted understanding, chemical elements are only a graphical display of atoms. Particles from which all existing in the universe is developing. That is, the question "What is chemical elements" can give such an answer. These are complex small structures, the totality of all atomic isotopes, combined with a common name having their graphic designation (symbol).

To date, it is known about 118 elements that are open both in natural conditions and synthetically, by implementing nuclear reactions and nuclei of other atoms. Each of them has a set of characteristics, its location in the general system, the opening history and the name, and also performs a certain role in the nature and life of living beings. The study of these features is the science of chemistry. Chemical elements are the basis for the construction of molecules, simple and complex compounds, and consequently, chemical interactions.

History opening

The very understanding of what chemical elements has come only in the XVII century thanks to the work of a boiler. It was he who first spoke about this concept and gave him the following definition. These indivisible small simple substances, of which it is all around, including all complex.

Before this work, the views of alchemists were dominant, recognizing the theory of four elements - Empidal and Aristotle, as well as those who opened the "combustible principles" (sulfur) and "metallic principles" (mercury).

Virtually the entire XVIII century was spread by a completely erroneous theory of phlogiston. However, at the end of this period, Antoine Laurent Lavauzier proves that it is untenable. He repeats the formulation of the boil, but at the same time complements it the first attempt to systematize all elements known at that time, distributing them into four groups: metals, radicals, land, non-metals.

The next big step in understanding what chemical elements makes Dalton. He owns the merit of the opening of the atomic mass. On the basis of this, it distributes some of the known chemical elements in the order of increasing their atomic mass.

Stable intensive development of science and technology makes it possible 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 full and forever the consolidated classification of these particles.

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

Chemical elements system Mendeleev

The scientist basically laid the difference in the atomic mass and managed to ingeniously arrange all the well-known chemical elements in order of its increase. However, the depth and genius of his scientific thinking and foresight was that Mendeleev left empty places in his system, open cells for still unknown elements, which, according to a scientist, will be open in the future.

And everything turned out exactly as he said. Chemical elements of Mendeleev over time filled all empty cells. Each predicted scientist structure was opened. And now we can safely say that the system of chemical elements is represented by 118 units. True, the last three discovers are not yet officially confirmed.

By itself, the chemical element system is displayed graphically a table, in which elements are located according to the hierarchy of their properties, charges of nuclei and the characteristics of the structure of the electronic shells of their atoms. So, there are periods (7 pieces) - horizontal rows, groups (8 pieces) - vertical, subgroups (main and side within each group). Most often, two rows of families - lanthanoids and actinoids are made separately into the lower layers of the table.

The atomic mass of the element consists of protons and neutrons, the combination of which is called "Mass Number". The number of protons is determined very simple - it is equal to the sequence number of the element in the system. And since the atom as a whole is an electronic system, that is, having no charges at all, the number of negative electrons is always equal to the number of positive protons particles.

Thus, the characteristic of the chemical element can be given by its position in the periodic system. Indeed, almost everything is described in the cell: the sequence number, and therefore electrons and protons, the atomic mass (averaged value of all existing isotopes of this element). It can be seen in which period the structure is (it means that electrons will be located on so many layers). You can also predict the number of negative particles at the last energy level for the 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 if the proton is deducted from the mass number, that is, the sequence number. Thus, it is possible to obtain and compile a whole electron-graphic formula for each chemical element, which will accurately reflect its structure and show possible and manifested properties.

Distribution of elements in nature

The study of this issue is engaged in a whole science - Cosmochemistry. The data show that the distribution of elements in our planet repeats the same patterns in the universe. The main source of cores of lightweight, heavy and medium-sized atoms is nuclear reactions occurring in the depths of stars - nucleosynthesis. Thanks to these processes, the universe and outer space provided our planet with all available chemical elements.

Total of those known 118 representatives in natural natural sources were found 89. These are the fundamental, most common atoms. Chemical elements were also synthesized artificially, by bombarding neutron nuclei (nucleosynthesis in laboratory conditions).

Simple substances of such elements such as nitrogen, oxygen, hydrogen are considered the most numerous. Carbon is part of all organic matter, and therefore also occupies a leading position.

Classification by electronic structure of atoms

One of the most common classifications of all chemical elements of the system is the distribution of them on the basis of an electronic structure. By the time how much energy levels are part of the atom shell and which contains the latest valence electrons, four groups of elements can be distinguished.

S-elements

These are such that the last S-orbital is filled. This family includes elements of the first group of the main subgroup (or only one electron at the external level determines similar properties of these representatives as strong reducing agents.

P-elements

Total 30 pieces. Valence electrons are located on r-supro. These are elements that form the main subgroups with the third to the eighth group belonging to 3,4,5,6 periods. Among them, according to properties, both metals and typical non-metallic elements are found.

d-Elements and F-Elements

These are transition metals from 4 to 7 a large period. Total 32 elements. Simple substances can exhibit both acidic and basic properties (oxidative and restorative). Also amphoterny, that is, dual.

The F-family includes lanthanoids and actinoids, in which the latest electrons are located on F-orbitals.

Substances formed by elements: simple

Also, all classes of chemical elements are capable of exist in the form of simple or complex compounds. Thus, it is customary to be considered such as formed from the same structure in different numbers. For example, o 2 - oxygen or dicksorod, and about 3 ozone. Such a phenomenon is called allotropy.

Simple chemical elements forming the same connections are characteristic of each representative of the periodic system. But not all of them are the same in the manifest properties. So, there are simple substances of metals and non-metals. The first form the main subgroups with 1-3 group and all side subgroups in the table. Non-metals are formed the main subgroups of 4-7 groups. The eighth major part includes special elements - noble or inert gases.

Among all those open for today, simple elements are known under normal conditions 11 gases, 2 liquid substances (bromine and mercury), all other are solid.

Complex compounds

This is customary to attract all that consist of two and more chemical elements. Examples of mass, because more than 2 million are known chemical compounds! These are salts, oxides, bases and acids, complex compound compounds, all organic matter.

See also: List of chemical elements on atomic numbers and alphabetical list of chemical elements Contents 1 Symbols used at the moment ... Wikipedia

See also: List of chemical elements by symbols and alphabetical list of chemical elements This is a list of chemical elements, ordered in ascending order of atomic numbers. The table holds the name of the element, symbol, group and period in ... ... Wikipedia

Main article: Chemical Lists Contents 1 Electronic Configuration 2 Literature 2.1 NIST ... Wikipedia

Main article: Lists of chemical elements No. Symbol Name Hardness in MOO Hardness Vickers (GPA) Sliding for Brinnel (GPa) 3 Li Lithium 0.6 4 Be Beryllium 5.5 1.67 0,6 5 B BOR 9.5 49 6 C Carbon 1.5 (Graphite) 6 ... Wikipedia

See also: a list of chemical elements on atomic numbers and a list of chemical elements by symbols Alphabetical list of chemical elements. Nitrogen N Actinia AC Aluminum Al America am Argon Ar Astat at ... Wikipedia

Main article: Lists of chemical elements No. Symbol Russian name Latin name Etymology Names 1 H Hydrogenium hydrogen from Dr. Greek. ὕΔωρ "Water" and γεννάω "Bringing". 2 ... Wikipedia

List of symbols of chemical elements Symbols (signs), codes or abbreviations used for a brief or visual representation of the names of chemical elements and simple substances of the same name. First of all, these are symbols of chemical elements ... Wikipedia

Below are the names of erroneously open chemical elements (indicating the authors and dates of openings). All the following elements were discovered as a result of experiments set up more or less objectively, but, as a rule, is incorrect ... ... Wikipedia

Recommended values \u200b\u200bfor many properties of elements, along with various links, are collected on these pages. Any changes in the values \u200b\u200bof infobox must be compared with the values \u200b\u200band / or respectively ... ... Wikipedia

Chemical sign of the chlorine dukeloma molecule 35 The combats of chemical elements (chemical signs) The symbol of the chemical elements. Together with chemical formulas, diagrams and equations of chemical reactions form a formal language ... ... Wikipedia

Books

• English for physicians. 8th ed. , Murai Marianna Stepanovna, Orlova Larisa Konstantinovna, 384 pp. The purpose of the study manual to teach the reading and translation of British medical texts, conducting conversations in various areas of medicine. It consists of a brief introductory and phonetic and ... Category: Textbooks for universities Publisher: Flinta, Manufacturer: Flinta,
• English for physicians, Muravskaya M.S. The purpose of the textbook is to traine the reading and translation of English medical texts, conducting conversations in various areas of medicine. It consists of a brief introductory and phonetic and main ... Category: Tutorials and Tutorials Series: Publisher: Flinta,

See also: List of chemical elements on atomic numbers and alphabetical list of chemical elements Contents 1 Symbols used at the moment ... Wikipedia

See also: List of chemical elements by symbols and alphabetical list of chemical elements This is a list of chemical elements, ordered in ascending order of atomic numbers. The table holds the name of the element, symbol, group and period in ... ... Wikipedia

- (ISO 4217) Codes for the presentation of currencies and funds CODES FOR THE REPRESENTATION OF CODES POUR LA REPRÉSENTATION DES Monnaies Et Types de Fonds (FR.) ... Wikipedia

The simplest form of matter that can be identified by chemical methods. These are components of simple and complex substances, which are a set of atoms with the same nucleus charge. The charge of the atom core is determined by the number of protons in ... Encyclopedia Color

Content of 1 Paleolithic era 2 10 E millennium BC. e. 3 9 E millennium BC. E ... Wikipedia

Content of 1 Paleolithic era 2 10 E millennium BC. e. 3 9 E millennium BC. E ... Wikipedia

This term has other values, see Russians (values). Russian ... Wikipedia

Terminology 1 :: DW day number of the week. "1" corresponds to Monday to define the term from different documents: DW DUT The difference between Moscow and the worldwide coordinated time, expressed by the number of hours of definition of the term from ... ... Dictionary directory terms of regulatory and technical documentation

Indium (lat. Indium), in, chemical element III of the periodic Mendeleev periodic system; Atomic number 49, atomic weight 114.82; White shiny soft metal. The element consists of a mixture of two isotopes: 113 in (4.33%) and 115 in (95.67%); The last isotope has very weak β-radioactivity (half-life T ½ \u003d 6 · 10 14 years).

In 1863, German scientists F. Reich and T. Richter with a spectroscopic study of zinc decks found in the spectrum new lines belonging to an unknown element. On bright blue (indigo colors) the color of these lines the new element was called Indium.

Spread India in nature. Indium is a typical scattered element, its average content in the lithosphere is 1.4 · 10 -5% by weight. In magmatic processes, indium accumulation occurs in granites and other acidic rocks. The main processes of the concentration of India in the earth's crust are associated with hot water solutions forming hydrothermal deposits. Indium is associated with Zn, SN, CD and PB. Sfellerites, chalcopyrits and cassiterites are enriched with Indian on average 100 times (content near L, 4 · 10 -3%). Three minerals of India are known - native Indium, Cuins 2 roar and Indies in 2 s 4, but they are all extremely rare. The accumulation of India in sphalerites is of practical importance (up to 0.1%, sometimes 1%). India enrichment is characteristic of the fields of the Pacific ore belt.

Physical properties of India. India Tetragonal Crystal Grille with parameters A \u003d 4.583Å and C \u003d 4,936Å. Atomic radius 1.66Å; ion radii in 3+ 0.92Å, in + 1.30Å; Density of 7.362 g / cm 3. Indium Extraction, its t pl 156.2 ° C; T Kip 2075 ° C. Temperature coefficient of linear expansion 33 · 10 -6 (20 ° C); Specific heat capacity at 0-150 ° C 234,461 J / (kg · k), or 0.056 Cal / (g · ° C); Specific electrical resistance at 0 ° C 8.2 · 10 -8 Ohm · m, or 8.2 · 10 -6 ohm · cm; elastic module 11 N / m 2, or 1100 kgf / mm 2; Brinell hardness 9 MN / m 2, or 0.9 kgf / mm 2.

Chemical properties of India. In accordance with the electronic configuration of the 4D 10 5S 2 5p, 1 indium atoms in compounds exhibits valence 1, 2 and 3 (mainly). In the air in the solid compact state of India racks, but oxidized at high temperatures, and above 800 ° C is on the purple-blue flame, giving in 2 O 3 oxide - yellow crystals well soluble in acids. When indium heated, it is easily connected to halogens, forming soluble Haloenids InCl 3, Inbr 3, Ini 3. InCl 2 chloride is obtained in the heating of India in the HCl current, and the Incl 2 when heated in is generated by InCl. With sulfur indium forms sulphides in 2 s 3, ins; They give compounds ins · in 2 s 3 and 3ins · in 2 s 3. In water in the presence of oxidizing agents of India, slowly corps surfaces: 4in + 3o 2 + 6H 2 O \u003d 4in (OH) 3. In the acids of India, it is soluble, its normal electrode potential is -0.34 V, it is almost dissolved in alkalis. India salts are easily hydrolyzed; The product of hydrolysis is the main salts or hydroxide in (OH) 3. The latter is well soluble in acids and bad - in alkali solutions (with the formation of salts - indates): In (it) 3 + 3KOH \u003d K 3. Connections India of the lower degrees of oxidation is rather unstable; Inhal halides and black in 2 O oxide are very strong reducing agents.

Obtaining India. India is obtained from waste and intermediate products of zinc production, lead and tin. This raw material contains from thousands to tenths percentage of India. India extracts from three main steps: obtaining a rich product - concentrate India; processing of concentrate to rough metal; refining. In most cases, the initial raw materials are treated with sulfuric acid and translate indium into a solution from which concentrate is isolated by hydrolytic precipitation. Black Indies are highlighted mainly cementation on zinc or aluminum. Refined produce chemical, electrochemical, distillation and crystal flip physical methods.

Application India. The most widespread Indies and its compounds (for example, Inn nitride, INP phosphide, InSB antimonide) are used in semiconductor techniques. Indium is used for various anti-corrosion coatings (including bearish). Individual coatings have a high reflectivity, which is used for the manufacture of mirrors and reflectors. Some Alloys of India are industrial importance, including low-melting alloys, glass gluing solders with metal and others.

The chemical element is a collective term that describes the combination of the atoms of a simple substance, that is, this that cannot be divided into any simpler (according to the structure of their molecules) components. Imagine that you get a piece of pure iron with a request to divide it on hypothetical components using any device or method ever invented by chemists. However, you will not be able to do anything, never iron is divided into something simpler. Simple substance - the gland - corresponds to the chemical element Fe.

Theoretical definition

The experimental fact noted above can be explained by this definition: the chemical element is an abstract combination of atoms (not molecules!) The corresponding simple substance, i.e. atoms of the same species. If there was a way to look at each of the individual atoms in a piece of pure iron mentioned above, then all of them would be the same - iron atoms. In contrast, the chemical compound, for example, iron oxide, always contains at least two different types of atoms: iron atoms and oxygen atoms.

Terms that need to know

Atomic mass: The mass of protons, neutrons and electrons, which constitute an atom of the chemical element.

Atomic number: The number of protons in the kernel of the element atom.

Chemical symbol: Letter or a pair of Latin letters representing the designation of this element.

Chemical connection: A substance that consists of two or more chemical elements connected to each other in a certain proportion.

Metal: an element that loses electrons in chemical reactions with other elements.

Metalloid: An element that reacts sometimes as a metal, and sometimes both nonmetall.

Non-metal: an element that seeks to obtain electrons in chemical reactions with other elements.

Periodic system of chemical elements: Classification system of chemical elements in accordance with their atomic numbers.

Synthetic element: The one that is obtained artificially in the laboratory, and, as a rule, does not occur in nature.

Natural and synthetic elements

Ninety two chemical elements are found in nature on Earth. The rest were obtained artificially in laboratories. The synthetic chemical element is, as a rule, a product of nuclear reactions in particle accelerators (devices used to increase the speed of subatomic particles, such as electrons and protons) or nuclear reactors (devices used to control the energy released during nuclear reactions). The first synthetic element with atomic number 43 was technologies discovered in 1937 by Italian physicists K. Perry and E. Segre. In addition to technetium and war, all synthetic elements have large kernels than uranium. The latter of its name, the synthetic chemical element is Livermiori (116), and before him was Fleemi (114).

Two dozen common and important elements

* If the value is not specified, the element is less than 0.1 percent.

Big explosion as the root cause of matter

What chemical element was the very first in the universe? Scientists believe that the answer to this question lies in the stars and in the processes with which the stars are formed. The universe is believed to have arisen at some point from 12 to 15 billion years ago. Up to this point, nothing except energy does not think. But something happened that turned this energy into a huge explosion (the so-called big explosion). In the next seconds after a large explosion, matter began to form.

The first people who appeared the simplest form of matter were protons and electrons. Some of them are combined into hydrogen atoms. The latter consists of one proton and one electron; This is the easiest atom that can exist.

Slowly, for long periods of time, hydrogen atoms began to be collected together in certain areas of space, forming dense clouds. Hydrogen in these clouds was tightened into compact formation by gravitational forces. In the end, these hydrogen clouds have become dense enough to form stars ..

Stars like chemical reactors of new elements

The star is just a mass of a substance that generates the energy of nuclear reactions. The most common of these reactions is a combination of four hydrogen atoms forming one helium atom. As soon as the stars began to form, the helium became the second element that appeared in the Universe.

When the stars are becoming older, they move from hydrogen-helium nuclear reactions to their other types. In them, helium atoms form carbon atoms. Later, carbon atoms form oxygen, neon, sodium and magnesium. Even later, neon and oxygen are connected to each other with the formation of magnesium. Since these reactions continue, all more and more chemical elements are formed.

The first systems of chemical elements

More than 200 years ago, chemists began to look for ways to classify them. In the mid-nineteenth century, about 50 chemical elements were known. One of the questions that have sought to resolve chemists. Comes down to the following: Chemical element is a completely different substance from any other element? Or some elements associated with others in some way? Is there a general law, which unites them?

Chemists offered various chemical elements systems. Thus, for example, the English chemist William Prat in 1815 suggested that the atomic masses of all elements are multiple mass of the hydrogen atom, if we take it equal to one, that is, they must be integers. At that time, the atomic masses of many elements have already been calculated by J. Dalton with respect to the mass of hydrogen. However, if for carbon, nitrogen, oxygen is approximately so, then chlorine with a mass of 35.5 in this scheme did not fit into any way.

German chemist Johann Wolfgang Doberiner (1780 - 1849) showed in 1829 that three elements from the so-called group of halogen (chlorine, bromine and iodine) can be classified according to their relative atomic masses. The atomic weight of bromine (79.9) was almost exactly the average of chlorine atomic scales (35.5) and iodine (127), namely, 35.5 + 127 ÷ 2 \u003d 81.25 (close to 79.9). It was the first approach to the construction of one of the groups of chemical elements. Doberiner discovered two more such elements triads, but it was not possible to formulate a common periodic law.

How a periodic system of chemical elements appeared

Most early classification schemes were not very successful. Then, around 1869, almost one discovery was made by two chemists and almost at one time. Russian Chemist Dmitry Mendeleev (1834-1907) and German chemist Julius Lothar Meyer (1830-1895) offered to organize elements that have similar physical and chemical properties in an ordered system of groups, rows and periods. At the same time, Mendeleev and Meyer indicated that the properties of chemical elements are periodically repeated depending on their atomic weights.

Today Mendeleev, as a rule, is considered a primary periodic law, because he took one step that Meyer did not. When all the items were located in the periodic table, some gaps appeared in it. Mendeleev predicted that these are places for elements that have not yet been discovered.

However, he went even further. Mendeleev predicted the properties of these not open elements. He knew where they are located in the periodic table, so that could predict their properties. It is noteworthy that each predicted chemical element of Mendeleev, future gallium, scandium and germanium were found in less than ten years after the publication of the periodic law.

Short form of a periodic table

There were attempts to calculate how many options for graphic images of the periodic system were offered different scientists. It turned out, more than 500. And 80% of the total number of options are tables, and the rest is geometric shapes, mathematical curves, etc. As a result, practical applications found four types of tables: short, half-hearted, long and staircase (pyramidal). The latter was proposed by the great physicist N. Borom.

The figure below shows a short form.

In it, the chemical elements are located ascending their atomic numbers from left to right and top down. Thus, the first chemical element of the periodic table hydrogen has atomic number 1 because the kernels of hydrogen atoms contain one and only one proton. Similarly, oxygen has atomic number 8, since the kernel of all oxygen atoms contain 8 protons (see figure below).

The main structural fragments of the periodic system are periods and groups of elements. In six periods, all cells are filled, the seventh has not yet been completed (elements 113, 115, 117 and 118, although synthesized in laboratories, but are not yet officially registered and have no names).

Groups are divided into main (a) and side (b) subgroups. Elements of the first three periods containing one row-line are included exclusively in A-subgroups. The remaining four periods include two rows.

Chemical elements in one group, as a rule, have similar chemical properties. Thus, the first group consists of alkaline metals, the second - alkaline earth. In one period, elements have properties, slowly varying from alkali metal to a noble gas. The figure below shows how one of the properties is atomic radius - varies for individual items in the table.

Long-range form of a periodic table

It is shown in the figure below and is divided into two directions, on rows and by columns. There are seven strings of periods, as in a short form, and 18 columns, called groups or families. In essence, an increase in the number of groups from 8 in a short form up to 18 in a long obtained by placing all elements in periods, starting from 4th, not in two, and in one line.

Two different numbering systems are used for groups, as shown in the top of the table. The system based on Roman digits (IA, IIA, IIB, IVB, etc.) was traditionally popular in the United States. Another system (1, 2, 3, 4, etc.) is traditionally used in Europe, and a few years ago was recommended for use in the United States.

The view of the periodic tables in the figures above is misleading, as in any such published table. The reason for this is that two groups of elements shown in the lower part of the tables should actually be located inside them. Lantanoids, for example, belong to the period 6 between Barium (56) and Hafne (72). In addition, actinoids belong to the period 7 between the radium (88) and the Rangeford (104). If they were inserted into the table, it would have become too wide to fit on a sheet of paper or wall chart. Therefore, these elements are accepted at the bottom of the table.