Chemical elements where and what are used. Chemical elements. Natural and synthetic elements

Some of the most popular chemical questions are: “How much is known now? chemical elements?", "How many chemical elements are there?", "Who discovered them?"
These questions do not have a simple and unambiguous answer.
What does "known" mean? Are they found in nature? On land, in water, in space? Have their properties been obtained and studied? Properties of what? Are substances in the form of phases or only at the atomic-molecular level? Available modern technologies make it possible to detect several atoms... But the properties of a substance cannot be determined from a single atom.
What does “exist” mean? IN in practical terms this is understandable: they are present in nature in such quantities and for so long that they and their compounds can have a real impact on natural phenomena. Or at least it was possible to study their properties in the laboratory.
About 88 such chemical elements have been identified in nature. Why so many? Because among elements with a serial number less than 92 (before uranium), technetium (43) and francium (87) are absent in nature. Virtually no astatine (85). No promethium (61).
On the other hand, both neptunium (93) and plutonium (94) (unstable transuranium elements) are found in nature where uranium ores occur.
All elements following plutonium Pu in D.I. Mendeleev’s periodic table are practically absent in the earth’s crust, although some of them are undoubtedly formed in space during supernova explosions. But they don't live long...
The discovery of francium - element No. 87 is interesting. This element was “invented” by D.I. Mendeleev, who, based on the periodic table he created, suggested that the group of alkali metals lacks the heaviest element, which he called ecacesium.
It is now known that no more than 30 grams of francium are present in the earth’s crust. It is a radioactive element and its longest-lived isotope, francium-210, has a half-life of 19.3 minutes.
France can be considered last element discovered on Earth as contained in nature (Margaret Pere, a student of Marie Skłodowska-Curie, in 1929; officially recognized and named in 1938).
All subsequent elements were obtained through the radioactive decay of chemical elements and using charged particle accelerators.
To date, scientists have synthesized 26 transuranic elements, starting with neptunium (N=93) and ending with element number N=118 (the element number corresponds to the number of protons in the atomic nucleus and the number of electrons around the atomic nucleus).
Transuranium chemical elements 93 to 100 are produced in nuclear reactors, and the rest are obtained as a result of nuclear reactions in particle accelerators. The technology for producing transuranium elements at accelerators is fundamentally clear: suitable positively charged cores of the elements are accelerated electric field to the required speeds and collide them with a target containing other heavier elements - processes of fusion and decay occur atomic nuclei various elements. The products of these processes are analyzed and conclusions are drawn about the formation of new elements.
German scientists from the Helmholtz Center for the Study of Heavy Ions in a series of experiments in 2013-2014 planned to obtain the next, 119th element of the periodic table, but failed. They bombarded berkelium nuclei (N=97) with titanium nuclei (N=22), but analysis of the experimental data did not confirm the presence of a new element.
At present, the existence of one hundred and eighteen chemical elements can be considered identified. Reports of the discovery of 119 - the first element of period 8 - can for now be considered probably reliable.
There have been claims of synthesis of the element unbiquadium (124) and indirect evidence of the elements unbinilium (120) and unbihexium (126) - but these results are still being confirmed.
Now, finally, all of the 118 elements officially known and proven to date have generally accepted names approved by IUPAC. Not long ago, the heaviest element to have an officially recognized name was the 116th element, which received it in May 2012 - livermorium. At the same time, the name of the 114th element - flerovium - was officially approved.
How many chemical elements can you get? Theoretically, the possibility of synthesizing elements numbered 121-126 is predicted. These are the numbers of protons in the nuclei of elements. Problem lower limit The periodic table remains one of the most important in modern theoretical chemistry.
Each chemical element has several isotopes. Isotopes are atoms whose nuclei have the same number of protons, but a different number of neutrons. The world of atomic nuclei of chemical elements is very diverse. About 3,500 nuclei are now known, differing from each other either in the number of protons, or in the number of neutrons, or both. Most of them are obtained artificially. The question is very interesting - how many isotopes can a given element have?
There are 264 known atomic nuclei that are stable, that is, they do not experience any rapid spontaneous transformations over time. Decays.
The remaining 3236 cores are susceptible various types radioactive decay: alpha decay (emission of alpha particles - nuclei of the helium atom); beta decay (simultaneous emission of an electron and an antineutrino or a positron and a neutrino, as well as the absorption of an electron with the emission of a neutrino); gamma decay (emission of photons - high-energy electromagnetic waves).
Of the known chemical elements of Mendeleev’s periodic system that are found on Earth, only 75 have accurately and generally recognized authors who discovered them - discovered and strictly identified. Only under these conditions - detection and identification - is the discovery of a chemical element recognized.
In the actual discovery - isolating in pure form and studying the properties - chemical elements found in nature, scientists from only nine countries participated: Sweden (22 elements), England (19 elements), France (15 elements), Germany (12 elements). Austria, Denmark, Russia, Switzerland and Hungary account for the discovery of the remaining 7 elements.
Sometimes they indicate Spain (platinum) and Finland (yttrium - in 1794, the Finnish chemist Johan Gadolin discovered an oxide of an unknown element in a Swedish mineral from Ytterby). But platinum, as a noble metal, has been known in its native form since ancient times - platinum in its pure form from ores was obtained by the English chemist W. Wollaston in 1803. This scientist is better known as the discoverer of the mineral wollastonite.
Yttrium metal was first obtained in 1828 by the German scientist Friedrich Wöhler.
The record holder among the “hunters” of chemical elements can be considered the Swedish chemist K. Scheele - he discovered and proved the existence of 6 chemical elements: fluorine, chlorine, manganese, molybdenum, barium, tungsten.
To the achievements in the discovery of chemical elements of this scientist, one can also add a seventh element - oxygen, but he officially shares the honor of discovery with the English scientist J. Priestley.
Second place in the discovery of new elements belongs to V. Ramsay -
to an English or, more precisely, a Scottish scientist: they discovered argon, helium, krypton, neon, xenon. By the way, the discovery of “helium” is very original. This is the first non-chemical discovery of a chemical element. Now this method is called "Absorption spectrophotometry". It is now attributed to W. Ramsay, but was made by other scientists. It happens often.
On August 18, 1868, the French scientist Pierre Jansen, in full solar eclipse in the Indian city of Guntur, for the first time explored the chromosphere of the Sun. He adjusted the spectroscope in such a way that the spectrum of the solar corona could be observed not only during an eclipse, but also on ordinary days. He identified, along with the hydrogen lines - blue, green-blue and red - a bright yellow line, which he initially mistook for the sodium line. Jansen wrote about this to the French Academy of Sciences.
It was subsequently found that this bright yellow line in the solar spectrum does not coincide with the sodium line and does not belong to any of the previously known chemical elements.
27 years after this initial discovery, helium was discovered on Earth - in 1895, Scottish chemist William Ramsay, examining a sample of the gas obtained from the decomposition of the mineral kleveite, discovered in its spectrum the same bright yellow line previously found in the solar spectrum. The sample was sent to additional research to the famous English spectroscopist William Crookes, who confirmed that the yellow line observed in the spectrum of the sample coincides with the D3 line of helium.
On March 23, 1895, Ramsay sent a message about his discovery of helium on Earth to the Royal Society of London, as well as to the French Academy through famous chemist Marcelena Berthelot. This is how the name of this chemical element came about. From the ancient Greek name of the solar deity - Helios. The first discovery made spectral method. Absorption spectroscopy.
In all cases, Ramsay had co-authors: W. Crooks (England) - helium; W. Rayleigh (England) - argon; M. Travers (England) - krypton, neon, xenon.
4 elements were found:
I. Berzelius (Sweden) - cerium, selenium, silicon, thorium;
G. Dewi (England) - potassium, calcium, sodium, magnesium;
P. Lecoq de Boisbaudran (France) - gallium, samarium, gadolinium, dysprosium.
Russia is responsible for the discovery of only one of the natural elements: ruthenium (44). The name of this element comes from the Late Latin name for Russia - Ruthenia. This element was discovered by Kazan University professor Karl Klaus in 1844.
Karl-Ernst Karlovich Klaus was a Russian chemist, the author of a number of works on the chemistry of platinum group metals, and the discoverer of the chemical element ruthenium. He was born in January 11 (22), 1796 - March 12 (24, 1864) in Dorpat, the ancient Russian city of Yuryev (now Tartu), in the family of an artist. In 1837, he defended his thesis for a master's degree and was appointed adjunct in the department of chemistry at Kazan University. From 1839 he became a professor of chemistry at Kazan University, and from 1852 – a professor of pharmacy at the University of Dorpat. In 1861 he became a Corresponding Member of the St. Petersburg Academy of Sciences.
The fact that most of the chemical elements known in nature were discovered by scientists from Sweden, England, France and Germany is quite understandable - in the 18-19 centuries, when these elements were discovered, it was in these countries that there was the highest level of development of chemistry and chemical technology .
Another interesting question: did women scientists discover chemical elements?
Yes. But a little. These are Marie Skladowska-Curie, who in 1898, together with her husband P. Curie, discovered polonium (the name is given in honor of her homeland Poland) and radium, Lise Meitner, who took part in the discovery of protactinium (1917), Ida Noddack (Tacke), who discovered in 1925, together with her future husband V. Noddak, Renius, and Margarita Perey, who in 1938 was officially recognized as the discovery of the element france and she became the first woman elected to the French Academy of Sciences (!!!).
In the modern periodic table there are several elements, in addition to ruthenium, whose names are associated with Russia: samarium (63) - from the name of the mineral samarskite, discovered by the Russian mining engineer V.M. Samarsky in the Ilmen Mountains, mendeleevium (101); dubnium (105). The history of the name of this element is interesting. This element was first obtained at the accelerator in Dubna in 1970 by G.N. Flerov’s group by bombarding 243Am nuclei with 22Ne ions and independently in Berkeley (USA) in the nuclear reaction 249Cf + 15N = 260Db + 4n.
Soviet researchers proposed to call new element nielsborium (Ns), in honor of the great Danish scientist Niels Bohr, Americans - ganium (Ha), in honor of Otto Hahn, one of the authors of the discovery of spontaneous fission of uranium.
Working group The IUPAC concluded in 1993 that the credit for discovering element 105 should be shared between the Dubna and Berkeley groups. The IUPAC Commission in 1994 proposed the name joliotium (Jl), in honor of Joliot-Curie. Before this, the element was officially called the Latin numeral - unnilpentium (Unp), that is, simply the 105th element. The symbols Ns, Na, Jl can still be seen in tables of elements published in previous years. For example, at the Unified State Exam in Chemistry 2013. According to the final decision of the IUPAC in 1997, this element was named "dubnium" - in honor of Russian center for research in the field of nuclear physics, science city Dubna.
At the United Institute nuclear research Dubna in different time superheavy chemical elements with serial numbers 113–118 were synthesized for the first time. Element number 114 was named “flerovium” - in honor of the Laboratory of Nuclear Reactions named after. G.N. Flerov of the Joint Institute for Nuclear Research, where this element was synthesized.
Over the past 50 years, the Periodic Table of D.I. Mendeleev was replenished with 17 new elements (102–118), of which 9 were synthesized at JINR. Including, in the last 10 years, 5 of the heaviest (superheavy) elements that close the periodic table...
For the first time, the 114th element has a “magic” number of protons (magic numbers are a series of natural even numbers corresponding to the number of nucleons in an atomic nucleus at which any of its shells becomes completely filled: 2, 8, 20, 28, 50, 82 , 126 (the last number is only for neutrons) - was obtained by a group of physicists led by Yu. Ts. Oganesyan at the Joint Institute for Nuclear Research (Dubna, Russia) with the participation of scientists from the Livermore National Laboratory (Livermore, USA; Dubna-Livermore collaboration) in December 1998, by synthesizing isotopes of this element through the fusion reaction of calcium nuclei with plutonium nuclei, the name of the 114th element was approved on May 30, 2012: “Flerovium” and the symbolic designation Fl. At the same time, the 116th element was named “livermorium”. (Livermorium) – Lv (by the way, the lifetime of this element is 50 milliseconds).
Currently, the synthesis of transuranium elements is mainly carried out in four countries: the USA, Russia, Germany and Japan. In Russia, new elements are obtained at the Joint Institute for Nuclear Research (JINR) in Dubna, in the USA - at the Oak Ridge National Laboratory in Tennessee and the Lawrence Livermore National Laboratory, in Germany - at the Helmholtz Center for the Study of Heavy Ions (also known as the Institute for Heavy Ions). ions) in Darmstadt, in Japan - at the Institute of Physical and Chemical Research (RIKEN).
For the authorship of the creation of the 113th element, there has long been a struggle between Japan and a Russian-American group of scientists. Japanese scientists led by Kosuke Morita synthesized element 113 in September 2004 by accelerating and colliding zinc-30 and bismuth-83. They were able to detect three decay chains corresponding to the chains of the birth of the 113th element in 2004, 2005 and 2012.
Russian and American scientists announced the creation of element 113 during the synthesis of element 115 in Dubna in February 2004 and proposed to call it becquerelium. Named after the outstanding physicist Antoine Henri Becquerel (French Antoine Henri Becquerel; December 15, 1852 - August 25, 1908) - French physicist, laureate Nobel Prize in physics and one of the discoverers of radioactivity.
Finally, at the beginning of 2016, the names of four new chemical elements were officially added to the periodic table. Elements with atomic numbers 113, 115, 117 and 118 are verified by the International Union of Pure and Applied Chemistry (IUPAC).
The honor of discovering elements 115, 117 and 118 was awarded to a team of Russian and American scientists from the Joint Institute for Nuclear Research in Dubna, Livermore National Laboratory in California and Oak Ridge National Laboratory in Tennessee.
Until recently, these elements (113, 115, 117 and 118) bore the not very sonorous names of ununtria (Uut), ununpentium (Uup), ununseptium (Uus) and ununoctium (Uuo), but within the next five months the discoverers of the elements will be able to give them new, final names.
Scientists from the Japanese Institute of Natural Sciences (RIKEN) are officially recognized as the discoverers of the 113th element. In honor of this, it was recommended to name the element “Japan”. The right to come up with names for the remaining new elements was given to the discoverers, for which they were given five months, after which they would be officially approved by the IUPAC council.
It is proposed to name the 115th element “Moskovium” in honor of the Moscow region!
It's finished! On June 8, 2016, the International Union of Pure and Applied Chemistry announced the recommended names for the 113th, 115th, 117th and 118th elements of the periodic table. This is reported on the union's website.
One of the new ones superheavy elements The periodic table number 113 officially received the name “nihonium” and the symbol Nh. The corresponding announcement was made by the Japanese Institute of Natural Sciences "Riken", whose specialists had previously discovered this element.
The word "nihon" is derived from the local name of the country - "Nihon".
The International Union of Pure and Applied Chemistry has approved the names of the new element numbers 113, 115, 117 and 118 - nihonium (Nh), moscovium (Mc), tennessine (Ts) and oganesson (Og).
The 113th element is named in honor of Japan, the 115th - in honor of the Moscow region, the 117th - in honor of the American state of Tennessee, the 118th - in honor of the Russian scientist, Academician of the Russian Academy of Sciences Yuri Oganesyan.
In 2019, Russia and the whole world celebrate the 150th anniversary of the discovery of the periodic table and the law that served as the basis of modern chemistry by Dmitry Ivanovich Mendeleev.
In honor of the anniversary, the UN General Assembly unanimously decided to hold the International Year of Mendeleev's Periodic Table of Elements.
"What's next?" - asks Yuri Oganesyan, scientific director of the nuclear reactions laboratory of the Joint Institute for Nuclear Research in Dubna, where the last five elements of the periodic table were discovered, including element-118, oganesson.
“It is clear that the periodic table does not end here and we need to try to obtain the 119th and 120th elements. But for this we will have to make the same technological revolution that helped us become leaders in the 1990s, increase the intensity of the particle beam by several orders of magnitude and make detectors much more sensitive,” the physicist emphasizes.
For example, scientists now produce one flerovium atom per week by firing trillions of particles per second at a target. More heavy elements(say, oganesson) can be synthesized only once a month. Accordingly, work on current installations will require an astronomically long time.
Russian researchers expect to overcome these difficulties with the help of the DC-280 cyclotron, launched in December last year. The density of the particle beam it produces is 10-20 times higher than that of its predecessors, which, as domestic physicists hope, will make it possible to create one of the two elements closer to the end of the year.
Element 120 will most likely be synthesized first, since the Californian target required for this has already been prepared at the American National Laboratory in Oak Ridge. Test launches of the DC-280, aimed at solving this problem, will take place in March this year.
Scientists believe that the construction of a new cyclotron and detectors will help get closer to the answer to another fundamental question: where does the periodic law cease to apply?
“Is there a difference between a synthetic and a natural element? When we open them and enter them into the table, it doesn’t indicate where they came from. The main thing is that they obey the periodic law. But now, it seems to me, we can already talk about this in the past time,” notes Oganesyan.

The word “element” in translation means “element”. What is a chemical element? This is a certain part that is independent, and at the same time is the basis of something. Even ancient scientists such as Horace and Cicero used this word in the very sense in which it is used in our time.

Let's take a closer look

A set of atoms that have the same nuclear charge, number of protons and coincide with the serial number in the periodic table are called a chemical element. In his Periodic Table of Elements, Mendeleev arranged the chemical elements, each of them has its own symbol and its own name.

Today, every student who starts studying chemistry at school should know what a chemical element is. He must know the symbols of chemical elements, which represent: the name of the element, one atom of the element and one mole of atoms of this element.

For the names of chemical elements, abbreviated symbols of chemical elements are used. First, use the first letter of the name of the chemical element, and if necessary, add another one. There is a number in front that indicates the number of atoms or moles of atoms of a particular chemical element.

Don't get confused

There is no need to confuse the definitions of a chemical element and a chemical substance. These are different concepts. A chemical substance consists of chemical elements, it can consist of one, or it can consist of different ones.

Eighty-eight elements are found in nature, and all the rest are derived artificially.

We all know that hydrogen fills our Universe by 75%. But do you know what other chemical elements there are that are no less important for our existence and play a significant role for the life of people, animals, plants and our entire Earth? The elements from this rating form our entire Universe!

10. Sulfur (abundance relative to silicon – 0.38)

This chemical element is listed under the symbol S in the periodic table and is characterized by atomic number 16. Sulfur is very common in nature.

9. Iron (abundance relative to silicon – 0.6)

Denoted by the symbol Fe, atomic number - 26. Iron is very common in nature, it plays a particularly important role in the formation of the inner and outer shell of the Earth's core.

8. Magnesium (abundance relative to silicon – 0.91)

In the periodic table, magnesium can be found under the symbol Mg, and its atomic number is 12. What is most amazing about this chemical element is that it is most often released when stars explode during the process of their transformation into supernovae.

7. Silicon (abundance relative to silicon – 1)

Denoted as Si. The atomic number of silicon is 14. This blue-gray metalloid is very rarely found in the earth's crust in its pure form, but is quite common in other substances. For example, it can even be found in plants.

6. Carbon (abundance relative to silicon – 3.5)

Carbon in the periodic table of chemical elements is listed under the symbol C, its atomic number is 6. The most famous allotropic modification of carbon is one of the most coveted precious stones in the world - diamonds. Carbon is also actively used in other industrial purposes for more everyday purposes.

5. Nitrogen (abundance relative to silicon – 6.6)

Symbol N, atomic number 7. First discovered by Scottish physician Daniel Rutherford, nitrogen most often occurs in the form of nitric acid and nitrates.

4. Neon (abundance relative to silicon – 8.6)

It is designated by the symbol Ne, atomic number is 10. It is no secret that this particular chemical element is associated with a beautiful glow.

3. Oxygen (abundance relative to silicon – 22)

A chemical element with the symbol O and atomic number 8, oxygen is essential to our existence! But this does not mean that it is present only on Earth and serves only for human lungs. The universe is full of surprises.

2. Helium (abundance relative to silicon – 3,100)

The symbol for helium is He, the atomic number is 2. It is colorless, odorless, tasteless, non-toxic, and its boiling point is the lowest of all chemical elements. And thanks to him, the balls soar skyward!

1. Hydrogen (abundance relative to silicon – 40,000)

The true number one on our list, hydrogen is found in the periodic table under the symbol H and has atomic number 1. It is the lightest chemical element on the periodic table and the most abundant element in the entire known universe.

Each chemical element is a collection of atoms with the same charge of atomic nuclei and the same number of electrons in the atomic shell. The nucleus of an atom consists of protons, the number of which is equal to the atomic number of the element, and neutrons, the number of which can vary. Varieties of atoms of the same chemical element having different mass numbers ( equal to the amount masses of protons and neutrons forming the nucleus) are called isotopes. In nature, many chemical elements are represented by two or a large number isotopes. Known 276 stable isotopes, belonging to 81 natural chemical Elements, and about 2000 radioactive isotopes. The isotopic composition of natural elements on Earth is usually constant; therefore, each element has an almost constant atomic mass, which is one of the most important characteristics element. More than 110 chemical elements are known; they, mostly non-radioactive, create a whole variety of simple and complex substances. A simple substance is a form of existence of an element in a free form. Some chemical elements exist in two or more allotropic modifications (for example, carbon in the form of graphite and diamond), differing in physical and chemical properties; number simple substances reaches 400. Sometimes the concepts of “element” and “simple substance” are identified, since in the overwhelming majority of cases there is no difference in the names of chemical elements and the simple substances they form; “...nevertheless, such a difference in concepts must always exist,” wrote D. I. Mendeleev in 1869. Taylor G. Basics organic chemistry for students of non-chemical specialties. - M.: 1989. Complex substance - chemical compound- consists of chemically bonded atoms of two or more different elements; more than 100 thousand inorganic and millions are known organic compounds. To designate chemical elements they are used chemical signs, consisting of the first or first and one of the subsequent letters of the Latin name of the element (With one exception, the second letter of the chemical Element Curium, named after Marie Skladowska-Curie, "m" means Maria). IN chemical formulas And chemical equations each such sign (symbol) expresses, in addition to the name of the element, the relative mass of the chemical element, equal to its atomic mass. The study of chemical elements constitutes the subject of chemistry, in particular inorganic chemistry. Artemenko A.I. Organic chemistry. - M., 2007

Historical reference. In the pre-scientific period of chemistry, the teaching of Empedocles that the basis of all things is made up of four elements was accepted as something immutable: fire, air, water, earth. This teaching, developed by Aristotle, was fully accepted by the alchemists. In the 8th-9th centuries, they supplemented it with the idea of ​​sulfur (the beginning of flammability) and mercury (the beginning of metallicity) as components of all metals. In the 16th century, the idea of ​​salt as the beginning of non-volatility and fire constancy arose. The doctrine of 4 elements and 3 principles was opposed by R. Boyle, who in 1661 gave the first scientific definition of chemical elements as simple substances that do not consist of any other substances or of each other and form all mixed (complex) bodies. In the 18th century, the hypothesis of I. I. Becher and G. E. Stahl, according to which the bodies of nature consist of water, earth and the principle of flammability - phlogiston, received almost universal recognition. At the end of the 18th century, this hypothesis was refuted by the works of A. L. Lavoisier. He defined chemical elements as substances that could not be decomposed into simpler ones and from which other (complex) substances are composed, that is, he essentially repeated Boyle’s formulation. But, unlike him, Lavoisier gave the first list of real chemical elements in the history of science. It included all non-metals known then (1789) (O, N, H, S, P, C), metals (Ag, As, Bi, Co, Ca, Sn, Fe, Mn, Hg, Mo, Ni, Au, Pt, Pb, W, Zn), as well as “radicals” [murium (Cl), fluoride (F) and boron (B)] and “earths” - not yet decomposed lime CaO, magnesia MgO, barite BaO, alumina Al2O2 and silica SiO2 (Lavoisier believed that “earths” were complex substances, but until this was proven experimentally, he considered them chemical elements). As a tribute to the times, he included weightless “fluids” - light and caloric - in the list of chemical elements. He considered the caustic alkalis NaOH and KOH to be complex substances, although it was possible to decompose them by electrolysis later - only in 1807 (G. Davy). J. Dalton's development of atomic theory had one of the consequences of clarifying the concept of an element as a type of atom with the same relative mass (atomic weight). Dalton in 1803 compiled the first table of atomic masses (relative to the mass of the hydrogen atom, taken as one) of the five chemical elements (O, N, C, S, P). Thus Dalton marked the beginning of recognition atomic mass How main characteristics element. Dalton, following Lavoisier, considered chemical elements to be substances that cannot be decomposed into simpler ones Artemenko A.I. Organic chemistry. - M., 2007.

The subsequent rapid development of chemistry led, in particular, to the discovery large number chemical elements. Lavoisier's list contained only 25 chemical elements, including "radicals", but not counting "fluids" and "earths". By the time of the discovery of Mendeleev's periodic law (1869), 63 elements were already known. The discovery of D.I. Mendeleev made it possible to foresee the existence and properties of a number of then unknown chemical elements and was the basis for establishing their relationship and classification. The discovery of radioactivity in the late 19th century shook more than a century of belief that atoms could not be broken down. In this regard, the discussion about what chemical elements are continued almost until the middle of the 20th century. Put an end to it modern theory structure of the atom, which made it possible to give a strictly objective definition of chemical elements given at the beginning of the article.

Prevalence in nature. The prevalence of chemical elements in space is determined by nucleogenesis inside stars. The formation of nuclei of chemical elements is associated with various nuclear processes in stars. Therefore on different stages their evolution, various stars and star systems have different chemical composition. The prevalence and distribution of chemical elements in the Universe, the processes of combination and migration of atoms during the formation of cosmic matter, and the chemical composition of cosmic bodies are studied by cosmochemistry. The bulk of cosmic matter consists of H and He (99.9%). The most developed part of cosmochemistry is geochemistry Akhmetov N.S. General and inorganic chemistry. - M., 2003.

Of the 111 chemical elements, only 89 are found in nature, the rest, namely technetium (atomic number Z = 43), promethium (Z = 61), astatine (Z = 85), francium (Z = 87) and transuranic elements, are obtained artificially through nuclear reactions (tiny amounts of Tc, Pm, Np, Fr are formed during the spontaneous fission of uranium and are present in uranium ores). In the accessible part of the Earth, the most common 10 elements with atomic numbers ranging from 8 to 26. In the earth's crust they are contained in the following relative quantities:

Classification and properties Akhmetov N.S. General and inorganic chemistry. - M., 2003. The most perfect natural classification of chemical elements, revealing their relationship and showing the change in their properties depending on atomic numbers, is given by D. I. Mendeleev’s periodic system of elements. According to their properties, chemical elements are divided into metals and non-metals, and the periodic system allows us to draw a boundary between them. For chemical properties metals is most characteristically manifested when chemical reactions the ability to donate external electrons and form cations; for nonmetals, the ability to gain electrons and form anions. Nonmetals are characterized by high electronegativity. There are chemical elements of the main subgroups, or non-transition elements, in which the s and p electron subshells are sequentially filled, and chemical elements of secondary subgroups, or transition elements, in which the d- and f-subshells are being completed. At room temperature two chemical elements exist in liquid state(Hg and Br), eleven - in gaseous form (H, N, O, F, Cl, He, Ne, Ar, Kr, Xe, Rn), the rest - in the form solids, and their melting point varies over a very wide range - from about 30 °C (Cs 28.5 °C; Ga 29.8 °C) to 3000 °C and higher (Ta 2996 °C; W 3410 °C; graphite about 3800 °C) Akhmetov N.S. General and inorganic chemistry. - M., 2003.

Chemical reactions involve the transformation of one substance into another. To understand how this happens, you need to remember from the course of natural history and physics that substances consist of atoms. There are a limited number of types of atoms. Atoms can connect to each other in different ways. How hundreds of thousands of letters are formed when adding the letters of the alphabet different words, 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. For example, several substances are known that are formed from only two types of atoms - oxygen atoms and hydrogen atoms, but different types molecules. These substances include water, hydrogen and oxygen. A water molecule consists of three particles bound to each other. These are atoms. An oxygen atom (oxygen atoms are designated in chemistry by the letter O) is attached to two hydrogen atoms (they are designated by the letter H). The oxygen molecule consists of two oxygen atoms; A hydrogen molecule is made up of two hydrogen atoms. Molecules can be formed during chemical transformations, or they can disintegrate. Thus, each water molecule breaks down into two hydrogen atoms and one oxygen atom. Two water molecules form twice as many hydrogen and oxygen atoms. Identical atoms bond in pairs to form molecules of new substances– hydrogen and oxygen. The molecules are thus destroyed, but the atoms are preserved. This is where the word “atom” comes 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 that made up the original substances. Just as microbes became accessible to observation with the invention of the microscope, so atoms and molecules became accessible to observation with the invention of instruments that provided even greater magnification and even made it possible to photograph atoms and molecules. In such photographs, atoms appear as blurry spots, and molecules appear as a combination of such spots. However, there are also phenomena in which atoms divide, atoms of one type turn into atoms of other types. At the same time, atoms that are not found in nature are also obtained artificially. But these phenomena are studied not 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 part of water molecules or part of other substances, these are atoms of the same chemical element. A chemical element is a specific type of atom How many types of atoms are there? Today, people reliably know about 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.

Chemical element symbols

In chemistry, chemical symbols are used to designate chemical elements. This is the language of chemistry. To understand speech in any language, you need to know the letters, and it’s the same in chemistry. 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, much less chemical elements were known than now. Alchemists identified them with planets, various animals, and ancient deities. Currently, the notation system introduced by the Swedish chemist Jöns Jakob Berzelius is used throughout the world. In his system, chemical elements are designated by the initial or one of the subsequent letters of the Latin name of a given element. For example, the element silver is represented by the symbol – Ag (lat. Argentum). Below are the symbols, symbol pronunciations, and names of the most common chemical elements. They need to be memorized!

The Russian chemist Dmitry Ivanovich Mendeleev was the first to organize the diversity of chemical elements, and based on what he discovered Periodic Law compiled the Periodic Table of chemical elements. How is the Periodic Table of chemical elements organized? Figure 58 shows the short-period version Periodic System. The Periodic Table 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 designated by 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 major. 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. There are main and secondary subgroups. Periodic Table – universal reference book chemist, with its help you can obtain information about chemical elements. There is another type of Periodic System - long-period In the long-period form of the Periodic Table, the elements are grouped differently, and are divided into 18 groups. In this version Periodic System elements are grouped into “families”, that is, within each group of elements there are elements with similar, similar properties. In this version Periodic System, group numbers, as well as periods, are indicated in Arabic numerals. Periodic System of Chemical Elements D.I. Mendeleev Characteristics of an element in the Periodic Table

Prevalence of chemical elements in nature

The atoms of elements found in nature are distributed very unevenly. In space, the most common element is hydrogen - the first element of 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% comes from 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 atoms of oxygen and silicon. Together with aluminum and iron they form the main compounds earth's crust. And iron and nickel- the main elements that make up the core of our planet. Living organisms are also composed of atoms of various chemical elements. The human body contains the most atoms of carbon, hydrogen, oxygen and nitrogen.

We draw conclusions from the article about Chemical elements.

• Chemical element– a certain type of atom
• Today, people reliably know about 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 Chemical Elements 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 secondary

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