Progress in the synthesis of new chemical elements. Reactions in which the nuclear charge changes. Accelerators and possibilities for synthesizing new elements. Who comes up with the name for the new elements?

The latest additions to the periodic table are elements 113 and 115, which do not yet have their own names

Preparation of superheavy elements 113 and 115 1. A beam of calcium-48 ions (one shown) is accelerated to high speeds in a cyclotron and directed at an americium-243 target.

2. The target atom is americium-243. A nucleus made of protons and neutrons and a fuzzy electron cloud surrounding it

3. Accelerated calcium-48 ion and target atom (americium-243) immediately before collision

4. At the moment of the collision, a new superheavy element with serial number 115 is born, living for only about 0.09 seconds

5. Element 115 decays to element 113, which already lives for 1.2 seconds, and then along a chain of four alpha decays, lasting about 20 seconds

6. Spontaneous decay of the final link in the chain of alpha decays - element 105 (dubnium) into two other atoms

Scientists from two leading Russian and American nuclear research centers abandoned the arms race and, finally getting down to business, created two new elements. If any independent researchers confirm their results, the new elements will be dubbed "ununtrium" and "ununpentium". Chemists and physicists around the world, not paying attention to the ugly names, express delight at this achievement. Ken Moody, head of the American team based in Livermore national laboratory Lawrence, states: “New perspectives are thus opened for the periodic table.”

The periodic table to which Moody refers is a familiar poster that adorns the walls of any room where more than two chemists might meet at the same time. We all studied it in chemistry lessons in high school or junior years of university. This table was created to explain why various elements combine in one way and not another. Chemical elements are placed in it in strict accordance with atomic weight and chemical properties. The relative position of an element helps predict the relationships it will enter into with other elements. After the creation of the 113th and 115th total number known to science elements reached 116 (117, if we count the element with serial number 118, the synthesis of which was already observed in Dubna in 2002, but this discovery has not yet been officially confirmed. - PM editors).

The history of the creation of the periodic table began in 1863 (however, timid attempts were made before: in 1817, I.V. Döbereiner tried to combine elements into triads, and in 1843, L. Gmelin tried to expand this classification with tetrads and pentads. - Editorial " PM"), when the young French geologist Alexandre-Émile Beguyer de Chancourtois arranged all the elements known at that time in a chain in accordance with their atomic weight. Then he wrapped a ribbon with this list around the cylinder, and it turned out that chemically similar elements lined up in columns. Compared to the trial and error method - the only research approach, which was used by chemists of that time - this trick with a ribbon looked like a radical step forward, although it did not bring serious practical results.

Around the same time, the young English chemist John A.R. Newlands experimented in the same way with relative position elements. He noted that chemical groups are repeated every eight elements (like notes, which is why the author called his discovery the “law of octaves.” - PM editors). Believing that a great discovery was ahead, he proudly delivered a message to the British Chemical Society. Alas! The older, more conservative members of this society killed this idea, declaring it absurd, and for many years it was consigned to oblivion. (You shouldn’t blame conservative scientists too much - the “law of octaves” correctly predicted the properties of only the first seventeen elements. - PM editors).

Russian revival

In the 19th century, the exchange of scientific information was not as active as it is now. Therefore, it is not surprising that another five years passed before the revival of the forgotten idea. This time the insight came to the Russian chemist Dmitry Ivanovich Mendeleev and his German colleague Julius Lothar Meyer. Working independently of each other, they came up with the idea of ​​arranging the chemical elements in seven columns. The position of each element was determined by its chemical and physical properties. And here, as de Chancourtois and Newlands had previously noticed, the elements spontaneously combined into groups that could be called “chemical families.”

Mendeleev managed to look deeper into the meaning of what was happening. The result was a table with empty cells showing exactly where to look for elements that had not yet been discovered. This insight looks even more fantastic if we remember that at that time scientists had no idea about the structure of atoms.

Over the next century, the periodic table became more and more informative. From the simple diagram shown here, it has grown into a huge sheet, including specific gravity, magnetic properties, melting and boiling points. You can also add information about the building here. electron shell atom, as well as a list of atomic weights of isotopes, that is, heavier or lighter twins that many elements have.

Artificial elements

Perhaps the most important news that the first versions of the periodic table brought to chemists was an indication of where the yet undiscovered elements were located.

By the beginning of the 20th century, the suspicion began to grow among physicists that atoms are not structured at all as was commonly thought. Let's start with the fact that these are not monolithic balls at all, but rather volumetric structures stretched out in empty space. The clearer the ideas about the microworld became, the faster the empty cells were filled.

Direct indications of the gaps in the table radically accelerated the search for elements that had not yet been discovered, but were actually present in nature. But when an accurate theory was formed that adequately described the structure of the atomic nucleus, new approach to “completing” the periodic table. A technique was created and tested for creating “artificial” or “synthetic” elements by irradiating existing metals with streams of high-energy elementary particles.

If you add electrically uncharged neutrons to the nucleus, the element becomes heavier, but its chemical behavior does not change. But as the atomic weight increases, elements become more and more unstable and acquire the ability to spontaneously decay. When this happens, some free neutrons and other particles are scattered into the surrounding space, but most of the protons, neutrons and electrons remain in place and are rearranged into the form of lighter elements.

Newcomers to the table

This February, researchers from LLNL (Lawrence Livermore National Laboratory) and the Russian Joint Institute for Nuclear Research (JINR), using the above-described atomic bombardment technique, obtained two completely new elements.

The first of these, element 115, was obtained after americium was bombarded with a radioactive isotope of calcium. (For reference, americium, a metal not often found in everyday life, is used in smoke detectors of common fire alarms.) The bombardment produced four atoms of element 115, but after 90 milliseconds they disintegrated to create another newborn - element 113. These four atoms lived for almost one and a half seconds before lighter elements already known to science were formed from them. Artificial elements rarely have longevity - their inherent instability is a consequence of the excessive number of protons and neutrons in their nuclei.

And now - regarding their awkward names. Several years ago, the International Union of Pure and Applied Chemistry (IUPAC), headquartered in Research Triangle Park, N.C. decreed that new chemical elements should be given culturally neutral names. Such neutrality can be achieved if you use the Latin pronunciation of the serial number of this element in the periodic table. Thus, the numbers 1, 1, 5 will be read “un, un, pent”, and the ending “ium” is added for reasons of linguistic coherence. (A neutral Latin name and corresponding three-letter symbol are given to the element temporarily until the International Union of Pure and Applied Chemistry approves its final name. The organization's guidelines, published in 2002, are that discoverers have priority in proposing a name for a new element , by tradition elements may be named after mythological events or characters (including celestial bodies), minerals, geographical regions, properties of the element, famous scientists. - Editorial Board "PM").

Even if these new elements do not live very long and are not found outside the walls of laboratories, their creation still means more than just filling empty cells and increasing the total number of elements known to science. “This discovery allows us to expand the applicability of fundamental principles of chemistry,” says Livermore Chief Moody, “and new advances in chemistry are leading to the creation of new materials and the development of new technologies.”

In the twentieth century, elements of the main subgroups Periodic table were less popular than those located in secondary subgroups. Lithium, boron and germanium found themselves in the shadow of their expensive neighbors - gold, palladium, rhodium and platinum. Of course, it must be admitted that the classical chemical properties of the elements of the main subgroups cannot be compared with the fast and elegant processes in which transition metal complexes participate (more than one award has been awarded for the discovery of these reactions). Nobel Prize). In the early 1970s, there was generally an opinion among chemists that the elements of the main subgroups had already revealed all their secrets, and their study was actually a waste of time.

Hidden chemical revolution

When the author of this article was a student (he received a diploma from Kazan University in 1992), he and many of his classmates studied chemistry p-elements seemed the most boring section. (Remember that s-, p- And d-elements are those whose valence electrons are occupied respectively s-, p- And d-orbitals.) We were told in what form these elements exist in earth's crust, taught methods for their isolation, physical properties, typical oxidation states, chemical properties and practical applications. It was doubly boring for those who went through chemical olympiads and learned all this useful information as a schoolchild. Perhaps that is why in our time the department is not organic chemistry was not very popular when choosing a specialization - we all tried to get into organics or organoelement specialists, where they talked about the era of transition metals that had come in chemistry, catalyzing all conceivable and inconceivable transformations of substances.

There were no computers or the Internet at that time; we received all the information only from abstract journals on chemistry and some foreign journals that our library subscribed to. Neither we nor our teachers knew that at the end of the 1980s the first signs of a renaissance in the chemistry of the elements of the main subgroups had already become noticeable. It was then that they discovered that it was possible to obtain exotic forms p-elements - silicon and phosphorus in low-coordinated and low-oxidized states, but at the same time capable of forming compounds that are quite stable at room temperature. Although about them practical application at that moment there was no talk, the first successful examples of the synthesis of these substances showed that the chemistry of the elements of the main subgroups was slightly underestimated and, perhaps, the time would come when p-elements will be able to emerge from the shadows d- and even f-elements. In the end, that’s what happened.

The year 1981 can be considered the starting point of the turn towards the elements of the main subgroups. At that time, as many as three works were published refuting the idea that a stable double or triple bond can be formed only if one of the partners of this chemical bond (or better yet, both) is an element of the second period. This “rule of double bonds” was first refuted by Robert West from the University of Wisconsin, in whose group they were the first to synthesize stable silene, a compound with a silicon-silicon double bond, a heavier analogue of alkenes, familiar to everyone from organic chemistry ( Science, 1981, 214, 4527, 1343–1344, doi: 10.1126/science.214.4527.1343). Shortly thereafter, researchers at the University of Tokyo, working under the direction of Masaaki Yoshifuji, reported the synthesis of a compound with a phosphorus-phosphorus double bond ( , 1981, 103, 15, 4587–4589; doi:10.1021/ja00405a054 ). In the same year, Gerd Becker from the University of Stuttgart was able to obtain a stable phosphaalkine, a compound with a phosphorus-carbon triple bond, which can be considered as a phosphorus-containing analogue of carboxylic acid nitriles ( Zeitschrift für Naturforschung B, 1981, 36, 16).

Phosphorus and silicon are elements of the third period, so no one expected such capabilities from them. In the latter compound, the phosphorus atom is coordinatively unsaturated, and this gave hope that it or its analogues would find use as catalysts. The reason for hope was that the main task of the catalyst is to contact the substrate molecule that needs to be activated; only those molecules that the reagent can easily approach are capable of this, and in the phosphates familiar to most chemists, the phosphorus atom, surrounded by four groups, is in no way possible call it an accessible center.

The main thing is the volumetric environment

All three syntheses, published in 1981, succeeded because the substituents surrounding the main subgroup elements in their new, exotic compounds were chosen correctly (in transition metal chemistry, the substituents were called ligands). The new derivatives obtained by West, Yoshifuji and Becker had one thing in common - bulky ligands associated with elements of the main subgroups stabilized silicon or phosphorus in a low-coordinated state that would not be stable under other circumstances. Bulk substituents protect silicon and phosphorus from oxygen and water in the air, and also prevent them from entering into a disproportionation reaction and taking on their typical oxidation states (+4 and +5 for silicon and phosphorus, respectively) and coordination numbers (four for both elements). Thus, silene was stabilized by four bulky mesityl groups (mesityl is 1,3,5-trimethylbenzene), and phosphaalkyne by a bulky tert-butyl substituent.

Once it became clear that bulky ligands make compounds in which p-elements are not in high degree oxidation and/or with a low coordination number, other scientists began to join in the production of new, unusual derivatives of elements of the main subgroups. Since the 2000s, in almost every issue Science(and since the appearance of the magazine in 2009 Nature Chemistry- in almost every issue) some exotic combination with an element of the main subgroups is reported.

Thus, until recently, no one could have thought that it would be possible to obtain and characterize stable silylenes - silicon-containing equivalents of carbenes.

Carbenes are highly reactive species in which the divalent and doubly coordinated carbon atom has either a pair of electrons (a more stable singlet carbene) or two separate unpaired electrons (a more reactive triplet carbene). In 2012, Cameron Jones from Australia's Monash University and his colleagues from Oxford and University College London described the first singlet silylene - divalent silicon in it is stabilized by a bulky boron ligand ( Journal of the American Chemical Society, 2012, 134, 15, 6500–6503, doi: 10.1021/ja301042u ). Silylene can be isolated in the crystalline state, and it is noteworthy that it remains stable at temperatures up to 130°C. But in solution, the silicon analogue of carbene dimerizes to form silene or is incorporated into C-H connections alkanes, reproducing the chemical properties of their carbene analogues.

Chemists continue to obtain new organic compounds containing elements of the main subgroups. In particular, they are trying to replace an element of the second period in a well-known structure with a similar element of an older period (this issue of Chemoscope talks about the preparation of a phosphorus-containing analogue of one of the first synthesized organic substances). Another direction is a bit like collecting rare stamps, only instead of stamps there are chemical structures. For example, in 2016, Alexander Hinz from Oxford tried to obtain a cycle containing atoms of four different pnictogens (elements of the 5th group of the main subgroup from nitrogen to bismuth). He failed to completely solve the problem - the molecule with a linear structure did not close in a cycle. However, the molecule with a unique Sb-N-As = P chain, including four of the five, is also impressive p-elements of the nitrogen subgroup ( Chemisrty. A European Journal, 2016, 22, 35, 12266–12269, doi: 10.1002/chem.201601916 ).

Of course, it is impossible to talk about the synthesis of exotic derivatives of elements of the main subgroups only as “chemical collecting”, since the production of analogues of well-known organic compounds, containing elements of older periods, is certainly important for clarifying theories of the structure of chemical bonds. Of course, this is not the only reason for the interest of chemists. The desire to find areas in which these substances can be used in practice is precisely the reason for the renaissance in the chemistry of elements of the main subgroups.

Back in the 1980s, after the synthesis of the first substances in which low coordination was observed p-elements, chemists hoped that such coordinatively unsaturated compounds would be able to catalyze many reactions in the same way as transition metal complexes. It would be very tempting to exchange expensive platinum and palladium compounds for molecules containing only elements of the main subgroups. Information about the properties of unusual compounds that appeared already in this millennium p-elements confirmed theoretical predictions. It turned out that many of them activate hydrocarbons, molecular hydrogen and carbon dioxide.

Why are transition metals bad?

It would seem, why develop new catalysts for processes that have long been perfectly accelerated by transition metal derivatives? In addition, the organometallic chemistry of transition elements does not stand still - new facets are opening up all the time reactivity d-elements. But noble transition metals have their drawbacks. First of all, the price: the most effective catalysts for the transformations of organic and organoelement compounds are complexes of rhodium, platinum and palladium. The second difficulty is the depletion of natural reserves of platinum and palladium. Finally, another problem with platinum or palladium catalysts is high toxicity. This is especially true when obtaining drugs, since their price is significantly increased by the cost of purifying a substance even from trace amounts of transition metals. The transition to new catalysts will at least significantly reduce the cost of the drug substance, and possibly simplify the purification of the target reaction product.

There are additional advantages that the use of catalysts based on elements of the main subgroups can provide. Thus, it is possible that some known reactions will take place under milder conditions, which means that it will be possible to save on energy. For example, back in 1981, in his work on the synthesis and properties of the first silene, Jones demonstrated that a compound with a silicon-silicon double bond can activate hydrogen at temperatures even lower than room temperature, whereas existing industrial hydrogenation processes require the use of high temperatures.

One of the important chemical processes discovered in the new millennium is the activation of molecular hydrogen with the help of digermin, a germanium-containing analogue of alkynes ( Journal of the American Chemical Society, 2005, 127, 12232–12233, doi: 10.1021/ja053247a ). This process, which may seem ordinary, is interesting for two reasons. Firstly, despite the analogy in the structure of alkynes and germines, hydrogen reacts with the latter not according to the scenario characteristic of hydrocarbons with a carbon-carbon triple bond (hydrogen attaches to each of the atoms of the triple bond, and germine turns into germene), but according to a mechanism typical for transition metal atoms. This mechanism, as a result of which a hydrogen molecule attaches to an element and two new E-H bonds are formed (in the described case, Ge-H), is called oxidative addition and is a key stage in many catalytic processes involving transition metals. Secondly, although H 2 may seem like the simplest and most straightforward molecule, chemical bond in it - the strongest of all that can arise between two identical elements, therefore the breaking of this bond and, accordingly, the activation of hydrogen in catalytic hydrogenation processes is far from simple task from the point of view of chemical technology.

Is it possible to make an acceptor a donor?

In order for an element to undergo the oxidative addition of hydrogen (regardless of where it is located on the Periodic Table), it must have certain characteristics electronic structure. Process E + H 2 = N-E-N will go only if the element is coordinatively unsaturated and its vacant orbital can accept electrons from molecular hydrogen. Moreover, the energy of this free orbital should be close to the energy of the molecular orbital of hydrogen, which contains electrons. Progress in the field of homogeneous metal complex catalysis is mainly explained by the fact that chemists, by changing the structure of ligands associated with a metal, can vary the energy of its orbitals and thus “adjust” them to strictly defined substances participating in the reaction. For a long time it was believed that such a soft adjustment of the energy of orbitals is possible only for d-elements, however, in the last decade it turned out that for p-elements too. Researchers pin their greatest hopes on nitrogen-containing complexes in which ligands, like claws, grip the coordination center (they are called chelating ligands, from the Latin c hela, claw), as well as with a relatively new class of ligands - N-heterocyclic carbenes.

A successful example of the latter is the work of Guy Bertrand from the University of California at San Diego, in which these ligands stabilize the boron atom ( Science, 2011, 33, 6042, 610–613, doi: 10.1126/science.1207573). Typically, boron derivatives, which contain only three electrons in their outer layer, act as a classical electron acceptor (Lewis acid). The fact is that boron needs five more electrons to reach a stable eight-electron shell, so three covalent bonds he can form three of his own and three third-party electrons, but he has to get two more electrons by accepting someone else’s electron pair into his empty electron cells. However N-heterocyclic carbenes are such strong electron donors that the boron associated with them ceases to be an acceptor - it becomes so "electron-rich" that it changes from a Lewis acid to a Lewis base. Until recently, chemists could not even predict such a significant change in the properties of the well-known p-element. And although Bertrand’s work is still interesting only from a theoretical point of view, the transition from theory to practice in our time is happening quite quickly.

How far is it to catalysis?

So, recently synthesized derivatives of elements of the main subgroups can enter into key reactions that catalyze transition metal complexes. Unfortunately, even the aforementioned oxidative addition of molecular hydrogen to a silicon or boron atom is only the first step in the sequence of reactions that must be developed for a complete catalytic cycle. For example, if we are talking about hydrogenation in the presence of compounds of the main subgroups, the mechanism of which reproduces the mechanism of hydrogen addition in the presence of Wilkinson’s catalyst, then after interaction with hydrogen p-element must form a complex with the alkene, then hydride transfer and complexation must occur... and all the other steps that will ultimately lead to the formation of the final product and regeneration of the catalytically active species. Only then will one catalyst particle produce tens, hundreds or even thousands of molecules of the target product. But in order for such a catalytic cycle to work, many more problems need to be solved - the element-hydrogen bond formed as a result of oxidative addition should not be too strong (otherwise hydride transfer will not occur), the element that has added hydrogen must maintain a low-coordinated state for interaction with an alkene and so on. If you miss some moment, the catalyst will disappear p-the element will not work, despite the similarity of its behavior with d-elements in some processes.

It may seem that the transition from metal complex catalysis to catalysis by compounds of elements of the main subgroups is too difficult a task, and it is very far from being completed. However, interest in chemistry p-elements and the desire of synthetic chemists to replace platinum or palladium catalysts with something else will certainly provide a breakthrough in this direction. There is a chance that we will hear about catalysts based on coordinatively unsaturated elements of the main subgroups within the next decade.

Physicists from the Livermore National Laboratory in the United States in January 2016 reported progress in inertial controlled thermonuclear fusion. Using new technology, scientists were able to quadruple the efficiency of such installations. The research results were published in the journal Nature Physics, and were briefly reported by the Livermore National Laboratory and the University of California at San Diego. Lenta.ru talks about new achievements.

People have long been trying to find an alternative to hydrocarbon energy sources (coal, oil and gas). Burning fuel pollutes environment. Its reserves are rapidly dwindling. The way out of the situation - dependence on water resources, as well as climate and weather - is the creation of thermonuclear power plants. To do this, it is necessary to achieve controllability of thermonuclear fusion reactions, which release the energy necessary for humans.

In thermonuclear reactors, heavy elements are synthesized from light ones (the formation of helium as a result of the fusion of deuterium and tritium). Conventional (nuclear) reactors, on the contrary, work on the decay of heavy nuclei into lighter ones. But for fusion it is necessary to heat the hydrogen plasma to thermonuclear temperatures (approximately the same as in the core of the Sun - one hundred million degrees Celsius or more) and keep it in an equilibrium state until a self-sustaining reaction occurs.

Work is being carried out in two promising areas. The first is associated with the possibility of confining heated plasma using magnetic field. Reactors of this type include a tokamak (a toroidal chamber with magnetic coils) and a stellarator. In a tokamak, an electric current is passed through a plasma in the form of a toroidal cord; in a stellarator, a magnetic field is induced by external coils.

The ITER (International Thermonuclear Experimental Reactor) under construction in France is a tokamak, and the Wendelstein 7-X, launched in December 2015 in Germany, is a stellarator.

The second promising direction of controlled thermonuclear fusion is associated with lasers. Physicists propose using laser radiation to quickly heat and compress matter to the required temperatures and densities so that, being in the state of inertially confined plasma, it ensures the occurrence of a thermonuclear reaction.

Inertial controlled thermonuclear fusion involves the use of two main methods of igniting a pre-compressed target: impact - using a focused shock wave, and fast - implosion (explosion inward) of a spherical hydrogen layer inside the target. Each of them (in theory) should ensure optimal conversion of laser energy into pulsed energy and its subsequent transfer to a compressed spherical thermonuclear target.

The installation at the National Laser Fusion Facility in the United States uses the second approach, which involves separating the compression and heating phases. This, according to scientists, makes it possible to reduce the density of the fuel (or its mass) and provide higher gain factors. Heating is generated by a short pulse of a petawatt laser: an intense electron beam transfers its energy to the target. The experiments reported in the latest study were conducted in New York City at the OMEGA-60 facility at the University of Rochester Laser Energy Laboratory, which includes 54 lasers with a total energy of 18 kilojoules.

The system studied by scientists is structured as follows. The target is a plastic capsule with a thin deuterium-tritium layer applied to the inner wall. When the capsule is irradiated with lasers, it expands and forces the hydrogen located inside it to contract (during the first phase), which is heated (during the second phase) to plasma. Plasma from deuterium and tritium gives x-ray radiation and presses on the capsule. This scheme allows the system not to evaporate after being irradiated by a laser and ensures more uniform heating of the plasma.

In their experiments, scientists introduced copper into the plastic shell. When a laser beam is directed at the capsule, it releases fast electrons, which strike the copper indicators and cause them to emit X-rays. For the first time, scientists were able to present a technique for visualizing K-shell electrons, which allows them to track the transfer of energy by electrons inside the capsule and, as a result, more accurately calculate the parameters of the system. The importance of this work is as follows.

Achieving a high degree of compression is hampered by fast electrons, whose energy is converted into a large fraction of the radiation absorbed by the target. The free path of such particles coincides in order with the diameter of the target, as a result of which it overheats prematurely and does not have time to compress to the required densities. The study made it possible to look inside the target and track the processes occurring there, providing new information about the laser parameters necessary for optimal radiation of the target.

In addition to the United States, work related to inertial thermonuclear fusion is being carried out in Japan, France and Russia. In the city of Sarov, Nizhny Novgorod region, on the basis of the All-Russian Scientific Research Institute of Experimental Physics, in 2020 it is planned to put into operation the UFL-2M dual-purpose laser installation, which, among other tasks, should be used to study the conditions of ignition and combustion of thermonuclear fuel.

The efficiency of a thermonuclear reaction is defined as the ratio of the energy released in the fusion reaction to total energy spent on heating the system to the required temperatures. If this value is greater than one (one hundred percent), the laser fusion reactor can be considered successful. In experiments, physicists managed to transfer up to seven percent of the energy of laser radiation to fuel. This is four times the efficiency of quick ignition systems previously achieved. Computer modelling allows you to predict an increase in efficiency of up to 15 percent.

The published results raise the odds that the US Congress will extend funding for megajoule facilities such as the National Laser Fusion Facility in Livermore, which cost more than $4 billion to build and maintain. Despite the skepticism that accompanies fusion research, it is slowly but surely moving forward. In this area, scientists face not fundamental, but technological challenges that require international cooperation and adequate funding.

The modern material and technical base of production is approximately 90% made up of only two types of materials: metals and ceramics. About 600 million tons of metal are produced annually in the world - over 150 kg. for every inhabitant of the planet. About the same amount of ceramics is produced along with bricks. The production of metal costs hundreds and thousands of times more, the production of ceramics is much easier technically and more economically profitable, and, most importantly, ceramics in many cases turns out to be a more suitable structural material compared to metal.

Using new chemical elements - zirconium, titanium, boron, germanium, chromium, molybdenum, tungsten, etc. Recently, fire-resistant, heat-resistant, chemical-resistant, high-hardness ceramics, as well as ceramics with a set of specified electrophysical properties, have been synthesized.

Superhard material - hexanite-R, as one of the crystalline varieties of boron nitride, with a melting point of over 3200 0 C and a hardness close to the hardness of diamond, has a record high viscosity, i.e. it is not as fragile as all other ceramic materials. Thus, one of the most difficult scientific and technical problems of the century has been solved: until now, all structural ceramics had a common drawback - fragility, but now a step has been taken to overcome it.

The great advantage of technical ceramics of the new composition is that machine parts are made from it by pressing powders to obtain finished products of given shapes and sizes.

Today we can name another unique property of ceramics - superconductivity at temperatures above the boiling point of nitrogen; this property opens up unprecedented scope for scientific and technological progress, for the creation of super-powerful engines and electric generators, the creation of magnetic levitation transport, the development of super-powerful electromagnetic accelerators for launching payloads into space, etc.

The chemistry of organosilicon compounds has made it possible to create large-scale production of a wide variety of polymers with fire-retardant, water-repellent, electrical insulation and other valuable properties. These polymers are indispensable in a number of energy and aviation industries.

Fluorocarbons are tetrafluoromethane, hexafluoroethane and their derivatives, where the carbon atom carries a weak positive charge, and the fluorine atom with the electronegativity inherent in fluorine has a weak negative charge. As a result, fluorocarbons have exceptional stability even in very aggressive environments of acids and alkalis, special surface activity, and the ability to absorb oxygen and peroxides. Therefore, they are used as a material for prostheses of human internal organs.

Question 57. Chemical processes and vital processes. Catalysts and enzymes.

Intensive recent research has been aimed at elucidating both the material composition of plant and animal tissues and the chemical processes occurring in the body. The idea of ​​the leading role of enzymes, first proposed by the great French naturalist Louis Pasteur (1822-1895), remains fundamental to this day. At the same time, static biochemistry studies the molecular composition and structure of tissue of living and nonliving organisms.

Dynamic biochemistry was born at the turn of the 18th and 19th centuries, when they began to distinguish between the processes of respiration and fermentation, assimilation and dissimilation as certain transformations of substances.

Fermentation research forms the main subject fermentology - core branch of knowledge about life processes. Over the course of a very long history of research, the process of biocatalysis has been considered from two different points of view. One of them, conventionally called chemical, was adhered to by J. Liebig and M. Berthelot, and the other, biological, was adhered to by L. Pasteur.

In the chemical concept, all catalysis was reduced to ordinary chemical catalysis. Despite the simplified approach, important provisions were established within the concept: an analogy between biocatalysis and catalysis, between enzymes and catalysts; the presence of two unequal components in enzymes - active centers and carriers; conclusion about the important role of transition metal ions and active centers of many enzymes; conclusion about the extension of the laws of chemical kinetics to biocatalysis; reduction in some cases of biocatalysis to catalysis by inorganic agents.

At the beginning of its development, the biological concept did not have such extensive experimental evidence. Its main support was the works of L. Pasteur and, in particular, his direct observations of the activity of lactic acid bacteria, which made it possible to identify fermentation and the ability of microorganisms to obtain the energy they need for life through fermentation. From his observations, Pasteur concluded that enzymes had a special level of material organization. However, all his arguments, if not refuted, were at least relegated to the background after the discovery of extracellular fermentation, and Pasteur’s position was declared vitalistic.

However, over time, Pasteur's concept won out. The promise of this concept is evidenced by modern evolutionary catalysis and molecular biology. On the one hand, it has been established that the composition and structure of biopolymer molecules represent a single set for all living beings, which is quite accessible for studying physical and chemical properties - the same physical and chemical laws govern both abiogenic processes and life processes. On the other hand, the exceptional specificity of living things has been proven, manifested not only in the highest levels of cell organization, but also in the behavior of fragments of living systems at the molecular level, which reflects the patterns of other levels. The specificity of the molecular level of living things lies in the significant difference in the principles of action of catalysts and enzymes, in the difference in the mechanisms of formation of polymers and biopolymers, the structure of which is determined only by the genetic code, and, finally, in its unusual fact: many chemical oxidation-reduction reactions in a living cell can occur without direct contact between reacting molecules. This means that chemical transformations can occur in living systems that have not been detected in the inanimate world.

The International Union of Pure and Applied Chemistry (IUPAC) has announced which names it considers most appropriate for the four new elements of the periodic table. It is recommended to name one of them in honor of the Russian physicist, academician Yuri Oganesyan. Shortly before this, the KSh correspondent met with Yuri Tsolakovich and did a long interview with him. But IUPAC is asking scientists not to comment until November 8, when the new names will be officially announced. Regardless of whose name appears in the periodic table, we can state: Russia has become one of the leaders in the transuranium race, which has been going on for more than half a century.

Yuri Oganesyan. Specialist in the field of nuclear physics, academician of the Russian Academy of Sciences, scientific director of the Laboratory of Nuclear Reactions at JINR, head of the Department of Nuclear Physics at the University of Dubna. As a student of Georgy Flerov, he participated in the synthesis of rutherfordium, dubnium, seaborgium, bohrium, etc. Among the world-class discoveries is the so-called cold fusion nuclei, which turned out to be an extremely useful tool for creating new elements.

In the lower lines of the periodic table you can easily find uranium, its atomic number is 92. All subsequent elements do not exist in nature now and were discovered as a result of very complex experiments.
American physicists Glenn Seaborg and Edwin MacMillan were the first to create a new element. This is how plutonium was born in 1940. Later, together with other scientists, Seaborg synthesized americium, curium, berkelium... The very fact of man-made expansion of the periodic table is in some sense comparable to a flight into space.

The leading countries of the world have entered the race to create super-heavy nuclei (if desired, an analogy could be drawn with the lunar race, but here our country is more likely to win). In the USSR, the first transuranium element was synthesized in 1964 by scientists from the Joint Institute for Nuclear Research (JINR) in Dubna, Moscow Region. It was the 104th element - called rutherfordium. The project was led by one of the founders of JINR, Georgiy Flerov. His name is also included in the table: flerovium, 114. And the 105th element was called dubnium.

Yuri Oganesyan was a student of Flerov and participated in the synthesis of rutherfordium, and then dubnium, seaborgium, bohrium... The successes of our physicists made Russia a leader in the transuranium race along with the USA, Germany, Japan (and perhaps the first among equals).

The new elements in question - 113, 115, 117, 118 - were synthesized in 2002–2009 at JINR at the U-400 cyclotron. In accelerators of this type, beams of heavy charged particles - protons and ions - are accelerated using high-frequency electric field, in order to then collide them with each other or with a target and study the products of their decay.

All experiments were carried out by international collaborations almost simultaneously in different countries. For example, scientists from the Japanese RIKEN Institute synthesized the 113th element independently of the others. As a result, the opening priority was given to them.

A new chemical element is first given a temporary name, derived from the Latin numeral. For example, ununoctium is "one hundred and eighteenth". Then the scientific team - the author of the discovery - sends its proposals to IUPAC. The commission is considering the arguments for and against. In particular, she recommends adhering to the following rules: “Newly discovered elements may be named: (a) after a mythological character or concept (including an astronomical object); (b) by the name of a mineral or similar substance; (c) by the name of a locality or geographic area; (d) in accordance with the properties of the element or (e) by the name of the scientist..."

Names should be easy to pronounce in most languages. known languages and contain information that allows an element to be unambiguously classified. For example, all transurans have two-letter symbols and end in “-iy” if they are metals: rutherfordium, dubnium, seaborgium, bohrium...

Whether the two new elements (115 and 118) will receive “Russian” names will become clear in November. But there are still many experiments ahead, because according to the hypothesis of islands of stability, there are heavier elements that can exist for a relatively long time. They are even trying to find such elements in nature, but it would be more accurate if Oganesyan synthesizes them at an accelerator.

Dossier on new elements

Serial number: 113

How and by whom it was discovered: a target of americium-243 was bombarded with calcium-48 ions and ununpentium isotopes were obtained, which decayed into isotopes of element 113. Synthesized in 2003.

Opening priority: Institute of Physical and Chemical Research (RIKEN), Japan.

Current name: ununtry.

Intended properties: heavy fusible metal.

Suggested name: nihonium (Nh). This element was the first to be discovered in Asia in general and Japan in particular. “Nihonii” is one of two options for the country’s self-name. "Nihon" translates to "land of the rising sun."

Serial number: 115

How and by whom it was discovered: americium-243 target was bombarded with calcium-48 ions. Synthesized in 2003. Priority in discovery: collaboration consisting of JINR (Russia), Livermore National Laboratory (USA) and Oak Ridge National Laboratory (USA).

Current name: ununpentium.

Intended properties: metal similar to bismuth.

Suggested name: moscovium (Moscovium, Mc). IUPAC approved the name “Moscow” in honor of the Moscow region, where Dubna and JINR are located. Thus, this Russian city can leave its mark on the periodic table for the second time: dubnium has long been officially called the 105th element.

Serial number: 117

How and by whom it was discovered: a berkelium-249 target was bombarded with calcium-48 ions. Synthesized in 2009. Priority for discovery: JINR, Livermore, Oak Ridge.

Current name: ununseptium.

Intended properties: formally refers to halogens like iodine. The actual properties have not yet been determined. Most likely, it combines the characteristics of a metal and a non-metal.

Suggested name: Tennessine (Ts). In recognition of the contributions of the State of Tennessee, USA, including Oak Ridge National Laboratory, Vanderbilt University, and the University of Tennessee, to the synthesis of transuraniums.

Serial number: 118

How and by whom it was discovered: a californium-249 target was bombarded with calcium-48. Synthesized in 2002. Priority in discovery: JINR, Livermore.

Current name: ununoctium.

Intended properties: By chemical characteristics refers to inert gases.

Suggested name: oganesson (Oganesson, Og). In honor of scientific supervisor Laboratory of Nuclear Reactions of JINR Yuri Oganesyan, who made a great contribution to the study of superheavy elements. Public discussion of possible names will last until November 8, after which the commission will make a final decision.

on "Schrodinger's Cat"