A chemical element is a collective term describing a set of atoms of a simple substance, that is, one that cannot be divided into any simpler (in terms of the structure of their molecules) constituents. Imagine receiving a piece of pure iron and asking you to break it down into hypothetical constituents using any device or method chemists have ever invented. However, there is nothing you can do, the iron will never split into something simpler. A simple substance - iron - corresponds to the chemical element Fe.

Theoretical definition

The experimental fact noted above can be explained using the following definition: a chemical element is an abstract set of atoms (not molecules!) Of the corresponding simple substance, i.e., atoms of the same type. If there was a way to look at each of the individual atoms in the piece of pure iron mentioned above, then they would all be the same - iron atoms. In contrast, a chemical compound such as iron oxide always contains at least two different kinds of atoms: iron atoms and oxygen atoms.

Terms you should know

Atomic mass: the mass of protons, neutrons, and electrons that make up an atom of a chemical element.

Atomic number: the number of protons in the nucleus of an atom of an element.

Chemical symbol: a letter or a pair of latin letters representing the designation of this element.

Chemical compound: a substance that consists of two or more chemical elements combined with 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 as a non-metal.

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

Periodic table of chemical elements: a system for classifying chemical elements according to their atomic numbers.

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

Natural and synthetic elements

Ninety-two chemical elements occur naturally on Earth. The rest were obtained artificially in laboratories. A synthetic chemical element is typically the 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 from nuclear reactions). The first synthetic element obtained with atomic number 43 was technetium, discovered in 1937 by the Italian physicists C. Perrier and E. Segre. Apart from technetium and promethium, all synthetic elements have nuclei larger than those of uranium. The last synthetic chemical element to get its name is livermorium (116), and before it was flerovium (114).

Two dozen common and important elements

* If no value is specified, then the element is less than 0.1 percent.

The Big Bang as the Root Cause of Matter Formation

What was the very first chemical element in the universe? Scientists believe the answer to this question lies in the stars and in the processes by which stars are formed. The universe is believed to have originated at some point in time between 12 and 15 billion years ago. Until this moment, nothing that exists, except energy, is not thought of. But something happened that turned this energy into a huge explosion (called the Big Bang). In the seconds after the Big Bang, matter began to form.

The first simplest forms of matter to appear were protons and electrons. Some of them combine to form hydrogen atoms. The latter consists of one proton and one electron; it is the simplest atom that can exist.

Slowly, over long periods of time, hydrogen atoms began to clump together in specific regions of space, forming dense clouds. The hydrogen in these clouds was pulled into compact formations by gravitational forces. Eventually, these clouds of hydrogen became dense enough to form stars.

Stars as chemical reactors of new elements

A star is simply a mass of matter that generates the energy of nuclear reactions. The most common of these reactions is a combination of four hydrogen atoms to form one helium atom. Once stars began to form, helium became the second element to appear in the universe.

As stars get older, they shift from hydrogen-helium nuclear reactions to other types of nuclear reactions. In them, helium atoms form carbon atoms. Later, carbon atoms form oxygen, neon, sodium and magnesium. Later still, neon and oxygen combine with each other to form magnesium. As these reactions continue, more and more chemical elements are formed.

The first systems of chemical elements

Over 200 years ago, chemists began looking for ways to classify them. In the middle of the nineteenth century, about 50 chemical elements were known. One of the questions that chemists have sought to resolve. boiled down to the following: a chemical element is a substance completely different from any other element? Or are some elements related to others in some way? Is there a common law uniting them?

Chemists have proposed various systems of chemical elements. For example, the English chemist William Prout in 1815 suggested that the atomic masses of all elements are multiples of the mass of the hydrogen atom, if we take it to be equal to unity, that is, they must be whole numbers. At that time, the atomic masses of many elements had already been calculated by J. Dalton in relation to the mass of hydrogen. However, if for carbon, nitrogen, oxygen this is approximately the case, then chlorine with a mass of 35.5 did not fit into this scheme in any way.

German chemist Johann Wolfgang Dobereiner (1780 - 1849) showed in 1829 that three elements from the so-called group of halogens (chlorine, bromine and iodine) can be classified according to their relative atomic masses. The atomic weight of bromine (79.9) turned out to be almost exactly the average of the atomic weights of chlorine (35.5) and iodine (127), namely 35.5 + 127 ÷ 2 = 81.25 (close to 79.9). This was the first approach to the construction of one of the groups of chemical elements. Dobereiner discovered two more such triads of elements, but he failed to formulate a general periodic law.

How the periodic table of chemical elements appeared

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

Today Mendeleev is generally regarded as the discoverer of the periodic law because he took one step that Meyer did not. When all the elements were located in the periodic table, some gaps appeared in it. Mendeleev predicted that these are locations for elements that have not yet been discovered.

However, he went even further. Mendeleev predicted the properties of these as yet undiscovered elements. He knew where they were on the periodic table so he could predict their properties. It is noteworthy that every predicted chemical element by Mendeleev, the future gallium, scandium and germanium, were discovered less than ten years after he published the periodic law.

Short form of the periodic table

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

The figure below shows the short form.

In it, chemical elements are arranged in ascending order of their atomic numbers from left to right and from top to bottom. So, the first chemical element of the periodic table hydrogen has atomic number 1 because the nucleus of hydrogen atoms contains one and only one proton. Likewise, oxygen has an atomic number of 8, since the nuclei of all oxygen atoms contain 8 protons (see figure below).

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

Groups are subdivided into main (A) and secondary (B) subgroups. Elements of the first three periods, each containing one row-row, are included exclusively in A-subgroups. The other four periods include two row-rows.

Chemical elements in the same group usually have similar chemical properties. So, the first group is made up of alkali metals, the second - alkaline earth metals. Elements located in the same period have properties slowly changing from an alkali metal to a noble gas. The figure below shows how one of the properties - the atomic radius - changes for individual elements in the table.

Long-period form of the periodic table

It is shown in the figure below and is divided in two directions, row and column. There are seven period lines, as in the short form, and 18 columns called groups or families. In fact, the increase in the number of groups from 8 in the short form to 18 in the long one is obtained by placing all the elements in the periods starting from the 4th, not in two, but in one line.

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

The look of the periodic tables in the figures above is a bit misleading, as is any such published table. The reason for this is that the two groups of items shown at the bottom of the tables should actually be located within them. Lanthanides, for example, belong to period 6 between barium (56) and hafnium (72). In addition, actinides belong to period 7 between radium (88) and rutherfordium (104). If they were inserted into a table, it would become too wide to fit on a piece of paper or a wall chart. Therefore, it is customary to place these elements at the bottom of the table.

In the book "The Skeptic Chemist" (1661). Boyle pointed out that neither the four elements of Aristotle nor the three principles of the alchemists can be recognized as elements. Elements, according to Boyle, are practically indecomposable bodies (substances), consisting of similar homogeneous (consisting of primary matter) corpuscles, of which all complex bodies are composed and into which they can be decomposed. Corpuscles can vary in shape, size, mass. The corpuscles from which the bodies are formed remain unchanged during the transformations of the latter.

However, Mendeleev was forced to make several permutations in the sequence of elements, distributed over increasing atomic weight, in order to observe the periodicity of chemical properties, and also to introduce empty cells corresponding to undiscovered elements. Later (in the first decades of the 20th century) it became clear that the periodicity of chemical properties depends on the atomic number (the charge of the atomic nucleus), and not on the atomic mass of the element. The latter is determined by the number of stable isotopes of the element and their natural abundance. Nevertheless, stable isotopes of an element have atomic masses grouping about a certain value, since isotopes with an excess or a lack of neutrons in the nucleus are unstable, and with an increase in the number of protons (that is, atomic number), the number of neutrons that form a stable nucleus in aggregate also increases. Therefore, the periodic law can also be formulated as the dependence of chemical properties on atomic mass, although this dependence is violated in several cases.

The modern understanding of a chemical element as a set of atoms characterized by the same positive nuclear charge, equal to the number of the element in the Periodic Table, appeared thanks to the fundamental works of Henry Moseley (1915) and James Chadwick (1920).

Known chemical elements[ | ]

The synthesis of new (not found in nature) elements with an atomic number higher than that of uranium (transuranic elements) was carried out at first with the help of multiple capture of neutrons by uranium nuclei under conditions of an intense neutron flux in nuclear reactors and even more intense - under conditions of a nuclear (thermonuclear ) explosion. The subsequent chain of beta decays of neutron-rich nuclei leads to an increase in the atomic number and the appearance of daughter nuclei with an atomic number Z> 92. Thus, neptunium ( Z= 93), plutonium (94), americium (95), berkelium (97), einsteinium (99) and fermium (100). Curium (96) and californium (98) can also be synthesized (and are practically obtained) in this way, but they were originally discovered by irradiating plutonium and curium with alpha particles at an accelerator. Heavier elements, starting with Mendelevium (101), are obtained only at accelerators, when actinide targets are irradiated with light ions.

The right to propose a name for a new chemical element is given to the discoverers. However, this name must follow certain rules. The report of the new discovery has been verified for several years by independent laboratories, and, if confirmed, by the International Union of Pure and Applied Chemistry (IUPAC; eng. International Union for Pure and Applied Chemistry, IUPAC) officially approves the name of the new element.

All 118 elements known as of December 2016 have permanent names approved by IUPAC. From the moment of the application for the discovery to the approval of the IUPAC name, the element appears under a temporary systematic name derived from the Latin numerals that form the digits in the atomic number of the element, and is denoted by a three-letter temporary symbol formed from the first letters of these numerals. For example, the 118th element, oganesson, before the formal approval of the permanent name had the temporary name of ununoctium and the symbol Uuo.

Unopened or unapproved elements are often named using the system used by Mendeleev - by the name of the superior homologue in the periodic table, with the addition of the prefixes "eka-" or (rarely) "dvi-", meaning Sanskrit numerals "one" and "two" ( depending on whether the homologue is 1 or 2 periods higher). For example, before the discovery of germanium (located under silicon in the periodic table and predicted by Mendeleev) was called eka-silicon, oganeson (ununoktium, 118) is also called eka-radon, and flerovium (ununkvadium, 114) is called eka-lead.

Classification [ | ]

Symbols of chemical elements[ | ]

Symbols for chemical elements are used as abbreviations for the names of elements. As a symbol, they usually take the initial letter of the element name and, if necessary, add the next or one of the following. Usually these are the initial letters of the Latin names of elements: Cu - copper ( cuprum), Ag - silver ( argentum), Fe - iron ( ferrum), Au - gold ( aurum), Hg - ( hydrargirum). Such a system of chemical symbols was proposed in 1814 by the Swedish chemist J. Berzelius. Temporary symbols of elements, used before the official approval of their permanent names and symbols, consist of three letters, meaning the Latin names of three digits in the decimal notation of their atomic number (for example, ununoctium - the 118th element - had a temporary designation Uuo). The notation system for the higher homologues described above (Eka-Rn, Eka-Pb, etc.) is also used.

Smaller numbers near the element symbol indicate: at the top left - atomic mass, at the bottom left - the ordinal number, at the top right - the ion charge, at the bottom right - the number of atoms in the molecule:

All elements following plutonium Pu (serial number 94) in the periodic system of D. I. Mendeleev are completely absent in the earth's crust, although some of them may be formed in space during supernova explosions [ ]. The half-lives of all known isotopes of these elements are short compared to the lifetime of the Earth. Long-term searches for hypothetical natural superheavy elements have not yet yielded results.

Most of the chemical elements, except for a few lightest ones, arose in the Universe mainly during stellar nucleosynthesis (elements before iron - as a result of thermonuclear fusion, heavier elements - during the sequential capture of neutrons by atomic nuclei and subsequent beta decay, as well as in a number of other nuclear reactions). The lightest elements (hydrogen and helium - almost completely, lithium, beryllium and boron - in part) were formed in the first three minutes after the Big Bang (primary nucleosynthesis).

One of the main sources of especially heavy elements in the Universe should be, according to calculations, the merger of neutron stars, with the release of significant amounts of these elements, which subsequently participate in the formation of new stars and their planets.

Chemical elements as an integral part of chemicals[ | ]

Chemical elements form about 500 simple substances. The ability of one element to exist in the form of various simple substances that differ in properties is called allotropy. In most cases, the names of simple substances coincide with the names of the corresponding elements (for example, zinc, aluminum, chlorine), however, in the case of the existence of several allotropic modifications, the names of a simple substance and an element may differ, for example, oxygen (dioxygen, O 2) and ozone (O 3) ; diamond, graphite and a number of other allotropic modifications of carbon exist along with amorphous forms of carbon.

Under normal conditions, 11 elements exist in the form of gaseous simple substances (,,,,,,,,,,), 2 - liquids (and), the rest of the elements form solids.

see also [ | ]

Chemical elements:

Links [ | ]

• B. M. Kedrov Evolution of the concept of an element in chemistry. M., 1956
• Chemistry and Life (Salter Chemistry). Part 1. Chemistry concepts. M .: Publishing house of the RCTU im. D. I. Mendeleeva, 1997
• Azimov A. A Brief History of Chemistry. St. Petersburg, Amphora, 2002
• Bednyakov V. A. "On the origin of chemical elements" E. Ch. A. Ya., Volume 33 (2002), Part 4 pp. 914-963.

Notes (edit) [ | ]

1. A team of authors. The meaning of the word "Chemical elements" in the Great Soviet Encyclopedia (unspecified) ... Soviet encyclopedia. Archived May 16, 2014.
2. Atoms and chemical elements.
3. Classes of inorganic substances.
4. , with. 266-267.
5. Discovery and Assignment of Elements with Atomic Numbers 113, 115, 117 and 118 (unspecified) .
6. Around the World - Chemical elements
7. Basic concepts of chemistry.
8. Marinov, A .; Rodushkin, I .; Kolb, D .; Pape, A .; Kashiv, Y .; Brandt, R .; Gentry, R. V .; Miller, H. W. Evidence for a long-lived superheavy nucleus with atomic mass number A = 292 and atomic number Z = ~ 122 in natural Th (English) // ArXiv.org: journal. - 2008.
9. Superheavy elements found in cosmic rays // Lenta.ru. - 2011.
10. Except for traces of primordial plutonium-244, which has a half-life of 80 million years; see Plutonium # Natural plutonium.
11. Hoffman, D. C .; Lawrence, F. O .; Mewherter, J. L .; Rourke, F. M. Detection of Plutonium-244 in Nature (English) // Nature: article. - 1971. - Iss. 234. - P. 132-134. - DOI: 10.1038 / 234132a0.
12. Rita Cornelis, Joe Caruso, Helen Crews, Klaus Heumann. Handbook of elemental speciation II: species in the environment, food, medicine & occupational health. - John Wiley and Sons, 2005 .-- 768 p. - ISBN 0470855983, 9780470855980.
13. Hubble opened the first kilonowa Archived August 8, 2013. // compulenta.computerra.ru
14. dated January 30, 2009 at the Wayback Machine (inaccessible link from 21-05-2013 -,).

Literature [ | ]

• Mendeleev D.I.,.// Encyclopedic Dictionary of Brockhaus and Efron: in 86 volumes (82 volumes and 4 additional). - SPb. , 1890-1907.
• Chernobelskaya G.M. Methodology for teaching chemistry in high school. - M.: Humanitarian publishing center VLADOS, 2000. - 336 p. - ISBN 5-691-00492-1.

All the variety of nature around us consists of combinations of a relatively small number of chemical elements. So what is the characteristic of a chemical element, and how does it differ from a simple substance?

Chemical element: history of discovery

In different historical epochs different meanings were put into the concept of "element". Ancient Greek philosophers considered 4 “elements” as such “elements” - heat, cold, dryness and humidity. Combining in pairs, they formed four "principles" of everything in the world - fire, air, water and earth.

In the 17th century, R. Boyle pointed out that all elements are material in nature and their number can be quite large.

In 1787 the French chemist A. Lavoisier created the "Table of Simple Bodies". It included all the elements known by that time. The latter meant simple bodies that could not be decomposed by chemical methods into even simpler ones. Subsequently, it turned out that some complex substances were also included in the table.

By the time DI Mendeleev discovered the periodic law, only 63 chemical elements were known. The discovery of the scientist not only led to an orderly classification of chemical elements, but also helped to predict the existence of new, not yet discovered elements.

Rice. 1. A. Lavoisier.

What is a chemical element?

A certain type of atom is called a chemical element. Currently, 118 chemical elements are known. Each element is denoted by a symbol that represents one or two letters from its Latin name. For example, the element hydrogen is denoted by the Latin letter H and the formula H 2 - the first letter of the Latin name for the element Hydrogenium. All fairly well-studied elements have symbols and names that can be found in the main and secondary subgroups of the Periodic Table, where they are all arranged in a specific order.

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There are many types of systems, but the generally accepted is the Periodic Table of Chemical Elements of D.I.Mendeleev, which is a graphic expression of the Periodic Law of D.I.Mendeleev. Usually, the short and long forms of the Periodic Table are used.

Rice. 2. Periodic table of elements of DI Mendeleev.

What is the main feature by which an atom is assigned to a particular element? D.I. Mendeleev and other scientists-chemists of the XIX century considered the main attribute of the atom to be mass as its most stable characteristic, therefore the elements in the Periodic Table are arranged in the order of increasing atomic mass (with a few exceptions).

According to modern concepts, the main property of an atom, referring it to a specific element, is the nuclear charge. Thus, a chemical element is a type of atoms characterized by a certain value (magnitude) of a part of a chemical element - the positive charge of the nucleus.

Of all the 118 chemical elements in existence, most (about 90) can be found in nature. The rest are obtained artificially using nuclear reactions. Elements 104-107 were synthesized by physicists at the Joint Institute for Nuclear Research in Dubna. At present, work continues on the artificial production of chemical elements with higher ordinal numbers.

All elements are divided into metals and non-metals. More than 80 elements are classified as metals. However, this division is conditional. Under certain conditions, some metals can exhibit non-metallic properties, and some non-metals, metallic properties.

The content of various elements in natural objects varies widely. 8 chemical elements (oxygen, silicon, aluminum, iron, calcium, sodium, potassium, magnesium) make up 99% of the earth's crust by mass, all the rest - less than 1%. Most of the chemical elements are of natural origin (95), although some of them were originally derived artificially (for example, promethium).

It is necessary to distinguish between the concepts of "simple substance" and "chemical element". A simple substance is characterized by certain chemical and physical properties. In the process of chemical transformation, a simple substance loses some of its properties and enters into a new substance in the form of an element. For example, nitrogen and hydrogen, which are part of ammonia, are contained in it not in the form of simple substances, but in the form of elements.

Some elements combine into groups such as organogens (carbon, oxygen, hydrogen, nitrogen), alkali metals (lithium, sodium, potassium, etc.), lanthanides (lanthanum, cerium, etc.), halogens (fluorine, chlorine, bromine, etc.), inert elements (helium, neon, argon)

Rice. 3. Halogens table.

What have we learned?

When introducing grade 8 chemistry into the course, first of all, it is necessary to study the concept of "chemical element". currently known 118 chemical elements, located in the table of D. I. Mendeleev according to the increase in atomic mass, and having basic acid properties.

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In chemical reactions, some substances are transformed into others. To understand how this happens, you need to remember from the course in natural history and physics that substances are composed of atoms. There are a limited number of types of atoms. Atoms can combine with each other in various ways. As when folding the letters of the alphabet, hundreds of thousands of different words are formed, so molecules or crystals of different substances are formed from the same atoms.

Atoms can form molecules- the smallest particles of a substance that retain its properties. It is known, for example, several substances formed from only two types of atoms - oxygen atoms and hydrogen atoms, but by different types of molecules. These substances include water, hydrogen and oxygen. A water molecule is made up of three particles bound together. These are atoms.

To the oxygen atom (oxygen atoms are denoted in chemistry by the letter O) are attached two hydrogen atoms (they are denoted by the letter H).

An oxygen molecule is made up of two oxygen atoms; a hydrogen molecule is made up of two hydrogen atoms. Molecules can be formed in the course of chemical transformations, or they can disintegrate. So, each water molecule splits into two hydrogen atoms and one oxygen atom. Two water molecules form twice the number of hydrogen and oxygen atoms.

Identical atoms bind in pairs to form molecules of new substances- hydrogen and oxygen. Molecules are thus destroyed and atoms are retained. Hence the word "atom" came from, which means in translation from ancient Greek "indivisible".

Atoms are the smallest, chemically indivisible particles of matter.

In chemical transformations, other substances are formed from the same atoms from which the original substances consisted. As microbes became available to observation with the invention of the microscope, so atoms and molecules - with the invention of devices that give even greater magnification and even allow atoms and molecules to be photographed. In such photographs, atoms appear as blurry spots, and molecules appear as a combination of such spots. However, there are also such phenomena in which atoms are divided, atoms of one type are converted into atoms of other types. At the same time, artificially obtained and such atoms that have not been found in nature. But these phenomena are not studied by chemistry, but by another science - nuclear physics. As already mentioned, there are other substances that contain hydrogen and oxygen atoms. But, regardless of whether these atoms are included in the composition of water molecules, or in the composition of other substances, these are atoms of the same chemical element.

Chemical element - a certain kind of atoms How many kinds of atoms are there? Today, man is reliably aware of the existence of 118 types of atoms, that is, 118 chemical elements. Of these, 90 types of atoms are found in nature, the rest are obtained artificially in laboratories.

Symbols of chemical elements

In chemistry, chemical symbols are used to denote chemical elements. This is the language of chemistry... To understand speech in any language, you need to know the letters, in chemistry it is exactly the same. To understand and describe the properties of substances, and the changes that occur with them, first of all, you need to know the symbols of chemical elements. In the era of alchemy, the chemical elements were much less known than they are now. Alchemists identified them with planets, various animals, and ancient deities. At present, the system of designations introduced by the Swedish chemist Jøns Jakob Berzelius is used all over the world. In his system, chemical elements are designated by the initial or one of the subsequent letters of the Latin name of the given element. For example, the element silver is denoted by the symbol - Ag (Latin Argentum). Below are the symbols, pronunciation of the symbols, and the names of the most common chemical elements. They need to be memorized!

The Russian chemist Dmitry Ivanovich Mendeleev was the first to organize the variety of chemical elements, and on the basis of the Periodic Law he discovered, he compiled the Periodic Table of Chemical Elements. How is the Periodic Table of Chemical Elements organized? Figure 58 shows a short-period variant of the Periodic Table. The Periodic System consists of vertical columns and horizontal rows. Horizontal lines are called periods. To date, all known elements are placed in seven periods.

The periods are denoted with Arabic numerals from 1 to 7. Periods 1-3 consist of one row of elements - they are called small.

Periods 4–7 consist of two rows of elements, they are called large. The vertical columns of the Periodic Table are called groups of elements.

There are eight groups in total, and Roman numerals from I to VIII are used to designate them.

Main and secondary subgroups are distinguished. Periodic System- a universal chemist's reference book, with its help you can get information about chemical elements. There is another type of the Periodic System - long-period. In the long-period form of the Periodic Table, the elements are grouped differently, and are divided into 18 groups.

PeriodicSystems elements are grouped by "families", that is, elements with similar, similar properties are located in each group of elements. In this version Periodic Table, group numbers, as well as periods, are denoted in Arabic numerals. Periodic Table of Chemical Elements D.I. Mendeleev

The prevalence of chemical elements in nature

The atoms of elements found in nature are very unevenly distributed in it. The most abundant element in space is hydrogen, the first element in the Periodic Table. It accounts for about 93% of all atoms in the universe. About 6.9% are helium atoms - the second element of the Periodic Table.

The remaining 0.1% is accounted for by all other elements.

The abundance of chemical elements in the earth's crust differs significantly from their abundance in the Universe. The earth's crust contains the most oxygen and silicon atoms. Together with aluminum and iron, they form the main compounds of the earth's crust. And iron and nickel- the main elements that make up the core of our planet.

Living organisms are also made up of atoms of various chemical elements. The human body contains the most atoms of carbon, hydrogen, oxygen and nitrogen.

The result of the article about Chemical elements.

• Chemical element- a certain kind of atoms
• Today, man is reliably aware of the existence of 118 types of atoms, that is, 118 chemical elements. Of these, 90 types of atoms are found in nature, the rest are obtained artificially in laboratories.
• There are two versions of the Periodic Table of the Chemical Elements of D.I. Mendeleev - short-period and long-period
• Modern chemical symbols are derived from the Latin names of chemical elements
• Periods- horizontal lines of the Periodic Table. Periods are divided into small and large
• Groups- vertical rows of the periodic table. Groups are divided into main and side

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