The place of chemistry in the modern scientific picture of the world. The concept of the unity of structural transformations of matter and the chemical picture of the world - abstract

History of Chemistry: Alchemy; the period of unification of chemistry (iatrochemistry, pneumatic chemistry, the phlogiston theory and its opponents, the period of quantitative laws (atomistic chemistry)); structuring of modern chemical knowledge.

Substance and element. Chemical systems. Energy of chemical processes. Physical bond and chemical reaction. Approaches to the classification of chemical reactions. The rate of a chemical reaction.

Periodic system of elements D. Mendeleev.

Chemistry of the Earth: geochemistry. Chemistry of Life: Biochemistry.

Application of chemical knowledge in industry, agriculture, medicine.

Module 3 Life Sciences

Topic 6. The specifics of a biological object and the problem of the origin of life

The specifics of living nature. The concepts of chaos and order. The unity of living and non-living. The boundaries of life. The phenomenon of life and its interpretation.

Approaches to identifying the specifics of living things: substrate, energy, information. Approaches to the definition of life: monoattributive, polyattributive.

Specificity and structure of biological knowledge. Tasks of modern biology: solving the problem of the emergence of a biological object, the systemic organization of the living, the evolution of a biological object.

Methodological significance of the principle of historicism in solving the problem of the origin of life. historical extrapolation.

The evolution of concepts of the origin of life. Biogenesis and abiogenesis. The concept of spontaneous generation of life. Experiments of L. Pasteur. The concept of panspermia and its evolution (S. Arrhenius, V.I. Vernadsky, Hooldane, Creek). Substratum concept of the origin of life.

Topic 7. The systemic nature of the living and the problem of the development of the organic world

The principle of consistency in the study of the living. The controversy of the mechanistic and vitalistic trends in biology. Features of living systems: evolutionism, irritability, availability and use of information, self-management, etc.

Criteria for identifying the levels of organization of the living. Orderliness of a biological object: spatial, functional, temporal aspects. Levels of organization of living things: a cell and its components, an organism and its properties; species, biogeocenosis.

The origin of the idea of the development of living nature in ancient natural philosophy. Naive transformation. Creationism. Systematization of the material of botany and zoology. The first taxonomic classifications.

The evolutionary doctrine of Ch. Darwin and the approval of the idea of development in biology. Driving forces and factors of evolution. The concepts of "heredity", "variability", "natural selection". Experimental study of individual factors of evolution. Genetics and evolution. Synthetic theory of evolution.

The problem of identifying system units of evolution: organism-centric and population approaches. Phylogeny and ontogeny. The problem of managing the evolutionary process.

Topic 8. The problem of the origin and essence of ideal processes

The concept and properties of cybernetic systems. The main stages of the process of cephalization. A forward reflection of reality. Irritability, sensitivity, psyche.

Properties of mental reflection of reality: purposefulness, integrity, subjectivity, objectivity, selectivity, experience, regulativeness.

Consciousness and its structure. Differences between the human mind and the mind of animals.

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questions

1. Chemistry as a science. 2. Alchemy as the prehistory of chemistry. 3. Evolution chemical science. 4. Ideas of D. I. Mendeleev and A. M. Butlerov. 5. Anthropogenic chemistry and its impact on the environment.

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from the Egyptian word "chemi", which meant Egypt, as well as "black". Historians of science translate this term as "Egyptian art". chemistry means the art of producing the necessary substances, including the art of converting ordinary metals into gold and silver or their alloys

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The word "chemistry" comes from the Greek term "chymos", which can be translated as "plant juice". "chemistry" means "the art of making juices," but the juice in question could also be molten metal. Chemistry can mean "the art of metallurgy".

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Chemistry - a branch of natural science that studies the properties of matter and their transformations

The main problem of chemistry is obtaining substances with desired properties. inorganic organic chemistry explores the properties of chemical elements and their simple compounds: alkalis, acids, salts. studies complex compounds based on carbon - polymers, including those created by man: gases, alcohols, fats, sugars

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The main periods in the development of chemistry

1. The period of alchemy - from antiquity to the 16th century. ad. It is characterized by the search for the philosopher's stone, the elixir of longevity, alkahest (universal solvent). 2. Period during the XVI - XVIII centuries. The theories of Paracelsus, the theories of gases by Boyle, Cavendish, and others, the theory of phlogiston by G. Stahl, and the theory of chemical elements by Lavoisier were created. Applied chemistry was improved, connected with the development of metallurgy, the production of glass and porcelain, the art of distillation of liquids, etc. TO late XVIII century there was a consolidation of chemistry as a science independent of other natural sciences.

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3. The first sixty years of the XIX century. It is characterized by the emergence and development of Dalton's atomic theory, Avogadro's atomic-molecular theory and the formation of the basic concepts of chemistry: atom, molecule, etc. 4. From the 60s of the XIX century to the present day. The periodic classification of elements, the theory of aromatic compounds and stereochemistry, the electronic theory of matter, etc. have been developed. The range of components of chemistry has expanded, as Not organic chemistry, organic chemistry, physical chemistry, pharmaceutical chemistry, chemistry food products, agrochemistry, geochemistry, biochemistry, etc.

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ALCHEMY

"Alchemy" is an Arabized Greek word, which is understood as "plant juice". 3 types: Greco-Egyptian, Arabic, Western European

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The birthplace of alchemy is Egypt.

Philosophical theory of Empedocles about the four elements of the Earth (water, air, earth, fire). According to it, various substances on Earth differ only in the nature of the combination of these elements. These four elements can be mixed into homogeneous substances. The most important problem in alchemy was the search for the philosopher's stone. Improved the process of refining gold by cupellation (heating gold-rich ore with lead and saltpeter). Isolation of silver by alloying ore with lead. The metallurgy of ordinary metals was developed. Known for the production of mercury.

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ARAB ALCHEMY

“chemi” in “al-chemistry” Jabir ibn Khayyam described ammonia, the technology for preparing white lead, a method for distilling vinegar to obtain acetic acid; all seven base metals are formed from a mixture of mercury and sulfur. and

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WESTERN EUROPEAN ALCHEMY

Dominican monk Albert von Bolstedt (1193-1280) - Albert the Great described in detail the properties of arsenic, expressed the opinion that metals consist of mercury, sulfur, arsenic and ammonia.

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12th century British philosopher - Roger Bacon (about 1214 - after 1294). possible inventor of gunpowder; wrote about the extinction of substances without access to air, wrote about the ability of saltpeter to explode with burning coal.

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Spanish physician Arnaldo de Villanova (1240-1313) and Raimund Lullia (1235-1313). attempts to get the philosopher's stone and gold (unsuccessfully), made potassium bicarbonate. Italian alchemist Cardinal Giovanni Fidanza (1121-1274) - Bonaventure received a solution of ammonia in nitric acid. The most prominent alchemist was a Spaniard, lived in the XIV century - Gebera. described sulfuric acid, described how nitric acid is formed, noted the property of aqua regia to act on gold, which until then was considered unchangeable.

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Vasily Valentin (XIV century) discovered sulfuric ether, hydrochloric acid, many compounds of arsenic and antimony, described methods for obtaining antimony and its medical use

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Theophrastus von Hohenheim (Paracelsus) (1493-1541), founder of iatrochemistry - medicinal chemistry, achieved some success in the fight against syphilis, one of the first to develop drugs to combat mental disorders, he is credited with the discovery of ether.

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Lecture 10Chemistry system.

1. The main problem of chemistry. Conceptual systems of chemistry.

2. The doctrine of the composition of matter. Solving the problems of a chemical element and a chemical compound. Periodic system of elements.

3. Structural chemistry.

4. Kinetic chemistry.

5. Evolutionary chemistry.

The main problem of chemistry as a science. Conceptual systems of chemistry. D. I. Mendeleev called chemistry "the science of chemical elements and their compounds." In some textbooks, chemistry is defined as "the science of substances and their transformations", in others - as "the science that studies the processes of qualitative transformation of substances", etc. All these definitions are good in their own way, but they do not take into account the fact that chemistry is not just a sum of knowledge about substances, but an ordered, constantly evolving system of knowledge, which has a certain social purpose and its place among other sciences.

The whole history of the development of chemistry is a natural process of changing the ways of solving its main problem. All chemical knowledge that has been acquired over the course of many centuries is subject to a single the main task of chemistry - the problem of obtaining substances with the necessary properties.

So, basic dual problem of chemistry- This:

1. Obtaining substances with desired properties is a production task.

2. Revealing ways to control the properties of a substance is the task of scientific research.

As science developed, ideas about the organization of matter, the composition of substances, and the structure of molecules changed, new data were obtained on the chemical processes themselves, which, of course, radically changed both the methods for the synthesis of new compounds and the methods for studying their properties. There is only four ways to solve this problem , which are associated primarily with the presence of only four main natural factors on which the properties of the substances obtained depend:

1. The composition of the substance (elementary, molecular).

2. Structure of molecules.

3. Thermodynamic and kinetic conditions of the chemical reaction during which this substance is obtained.

4. The level of organization of matter.

The successive appearance first of the first, then the second, third and, finally, the fourth ways of solving the basic problem of chemistry leads to the sequential appearance and coexistence of four levels of development of chemical knowledge, or, as they are now commonly called, four conceptual systems , located in a hierarchy relationship, i.e., subordination. In the system of all chemistry they are subsystems, just as chemistry itself is a subsystem of all Natural Science as a whole. The existence of only four ways to solve the basic problem of chemistry is reflected in the division of the System of Chemistry into four subsystems.

Thus, in the development of chemistry, there is not a change, but a strictly natural, consistent appearance of conceptual systems. Moreover, each newly emerging system does not deny the previous one, but, on the contrary, relies on it and includes it in a transformed form.

Summing up some results, we can give the following definition: Chemistry system -a single integrity of all chemical knowledge that appears and exists not separately from each other, but in close interconnection, complement each other and are combined into conceptual systems of chemical knowledge that are hierarchical with each other.

Each of the four historical stages in the extraction of chemical knowledge had its own tasks that needed to be solved.

The first stage in the development of chemistry - the XVII century: The doctrine of the composition of matter. The main problems facing scientists at the very first stage - the stage studying the composition of matter :

1. The problem of a chemical element.

2. The problem of a chemical compound.

3. The problem of creating new materials, which include newly discovered chemical elements.

An effective way to solve a problem originproperties of matter appeared in the second half of the 17th century. in the works of the English scientist Robert Boyle. His research showed that the qualities and properties of bodies are not absolute and depend on what material elements these bodies are composed of.

Boyle thus contributed to the solution of the basic problem of chemistry by establishing the relationship:

COMPOSITION OF THE SUBSTANCE ---------> PROPERTIES OF THE SUBSTANCE

This method laid the foundation for the doctrine of the composition of substances, which was first level scientific chemical knowledge . Until the first half of the 19th century. the doctrine of the composition of substances represented the entire chemistry of that time.

Solving the problem of a chemical element. The historical roots of solving this problem go back to ancient times. IN Ancient Greece the first atomistic theories about the structure of the world appear and, in contrast to them, ideas about the elements; properties and elements, qualities taken up later by the false teachings of the alchemists.

R. Boyle laid the foundation for the modern idea of a chemical element as a "simple" body or as the limit of the chemical decomposition of a substance. Chemists, trying to obtain "simple substances", used the most common method at that time - the calcination of "complex substances". Calcination also led to scale, which was taken as a new element. Accordingly, metals - iron, for example, were taken as complex bodies consisting of the corresponding element and the universal "weightless body" - phlogiston (phlogistos - Greek lit). The phlogiston theory (false in its essence) was the first scientific chemical theory and served as an impetus for many studies.

In 1680-1760. exact quantitative methods of analysis substances, and they, in turn, contributed to the discovery of true chemical elements. At this time they were open phosphorus, cobalt, nickel, hydrogen, fluorine, nitrogen, chlorine and manganese .

In 1772-1776. simultaneously opened in Sweden, England and France oxygen . In France, its discoverer was a remarkable chemist A.L. Lavoisier(1743-1794). He established the role of oxygen in the formation of acids, oxides and water, refuted the theory of phlogiston and created fundamentally new theory chemistry. He also owned the first attempt to systematize the chemical elements, which was later corrected by D. I. Mendeleev.

Periodic law and periodic system of chemical elements D.I. Mendeleev. The Russian chemist D. I. Mendeleev made this discovery in 1869, making a revolution in natural science, because. it not only established a relationship between the chemical and physical properties of individual elements, but also a mutual relationship between all chemical elements. Groups and series of the periodic system have become a reliable basis for identifying families of related elements.

N. B! The first practical application of the periodic law was to correct the valences and atomic weights of certain elements, for which incorrect values were assumed at that time. This applied, in particular, to indium, cerium, and other rare earth elements: thorium, uranium.

The basic principle on which Mendeleev built his table was to arrange the elements in ascending order of their atomic weights. Based on the valency and chemical properties of the elements, Mendeleev arranged all the elements into 8 groups, each of which contained elements with similar properties.

The reason for the periodic changes in the physical and chemical properties of elements lies inperiodicity of the structure of electron shells of atoms .

N. B! At the beginning of each period, the valence electrons are in the s-sublevels of the corresponding energy levels in the atoms. Then, in small periods, the s and p sublevels are filled with electrons, and in large periods, the d sublevels are also filled. In periods VI and VII, in addition, the filling of the f-sublevels is observed. Atoms of inert gases always contain outer electrons at fully formed s and p sublevels. Thus, the chemical elements of the same subgroups of the periodic system are characterized by a similar structure of the electron shells of the atom.

One of the most important properties of atoms related to the structure of their electron shells is the effective atomic and ionic radii. It turns out that they also change periodically depending on the value of the element's atomic number. For elements of the same period, as the serial number increases, first a decrease in atomic radii is observed, and then, towards the end of the period, their increase. This unusual physical property finds a simple explanation based on knowledge of the structure of the outer electron shell of atoms belonging to the same period: it's all about electrostatics.

But the most important thing was that the periodic table did not just explain the physical properties of the elements, but put them in line with their Chemical properties. The main postulate of the table was that valence chemical element is determined by the number of electrons in the outer electron shell(these electrons are called - valence electrons ).

An important role of the periodic law is that it establishes a connection between the structure of atoms and the influence of this structure on the physical and chemical properties of elements.

Solving the problem of a chemical compound. The beginning of the solution of this problem was laid thanks to the work of the French chemist J. Proust, which in 1801-1808. installed law of constancy of composition , Whereby any individual chemical compound has a strictly defined, unchanged composition - a strong attraction of its constituent parts (atoms) and thus differs from mixtures.

The theoretical justification for Proust's law was given by an Englishman J. Dalton, who is the author of another fundamental law in the doctrine of the composition of substances - law of multiple ratios . He showed that all substances consist of molecules, and all molecules, in turn, are made of atoms, and that the composition of any substance can be imagined as a simple formula like AB, AB2, A2 B3, etc., where the symbols A and B stands for the names of the two atoms that make up a molecule. According to this law of equivalents, the “components of a molecule” - atoms A and B can be replaced by other atoms - C and D, for example, according to the reactions:

AB + C --> AC + B or

A2B3 + 3D ---> A2D3 + 3B

Dalton's law of multiple ratios (1803) states: If a certain amount of one element enters into combination with another element in several weight ratios, then the quantities of the second element are related to each other as whole numbers.

The molecular theory of the structure of matter made it possible to take a fresh look at the processes occurring in the gas phase, and gave rise to a new science, standing at the intersection of chemistry and physics - molecular physics . The real sensation was the discovery Avogadro's law in 1811 Italian scientist Amadeo Avogadro(1776-1856) established that under the same physical conditions (pressure and temperature), equal volumes of different gases contain an equal number of molecules. In other words, this means that gram molecule Any gas at the same temperature and pressure occupies the same volume.

However, the development of chemistry and the study of an increasing number of compounds led chemists to the idea that, along with substances that have certain composition , there are also connections variable composition - and this was the reason for the revision of ideas about the molecule as a whole. A molecule, as before, continued to be called the smallest particle of a substance capable of determining its properties and existing independently, but now such unusual quantum mechanical systems, such as ionic, atomic and metallic single crystals , and polymers formed by hydrogen bonds.

As a result of the application of physical methods for the study of matter, it became clear that the properties of a real body are determined not so much by whether the composition of a chemical compound is constant or not, but rather the physical nature of chemistry, i.e. the nature of those forces that cause several atoms to combine into one molecule. So now under chemical compound understand a certain substance consisting of one or more chemical elements, the atoms of which, due to interaction with each other, are combined into a particle with a stable structure - a molecule, complex, single crystal or other aggregate. This is a broader concept than the concept of "complex substance". Indeed, after all, everyone knows chemical compounds that consist not of different, but of the same elements. These are molecules of hydrogen, oxygen, chlorine, graphite, diamond, etc.

A special position in the series of molecular particles is occupied by polymer macromolecules . They contain a large number of repeating, chemically related to each other structural units - fragments of monomeric molecules having the same chemical properties.

Further complication of the chemical organization of matter follows the path of formation of a more complex set of interacting atomic and molecular particles, the so-called molecular associates and aggregates , as well as their combinations. During the formation of aggregates, the phase state of the system changes, which does not occur during the formation of associates. F basic state -is the basic physical state in which any substance can exist(gas, liquid, solid).

The problem of creating new materials. Nature generously "scattered" its material resources throughout the planet. But what a strange pattern scientists have discovered: it turns out that most often in their activities a person uses those substances, the reserves of which are limited in nature.

Therefore, chemists currently face three tasks:

1. Bringing the practice of using chemical elements in production into line with their real resources in nature.

2. Successive replacement of metals by various types of ceramics.

3. Expansion of the production of organoelement compounds based on organic synthesis. Organoelement compounds I-these are compounds that include both organic elements (carbon, hydrogen, sulfur, nitrogen, oxygen) and derivatives of a number of other chemical elements: silicon, fluorine, magnesium, calcium, zinc, sodium, lithium, etc.

It is proposed to focus on increasing the use in the production of such elements as aluminum, magnesium, calcium, silicon. In nature, these elements are quite common, and their extraction is not difficult. In addition, the use of these substances, composed of the most commonly found natural elements, will lead to less environmental pollution with waste, a problem that is so acutely felt by everyone at the present time.

The increased need to replace metals with ceramics is due to the fact that the production of ceramics is easier and more economical, and, in addition, in some industries it simply cannot be replaced by metals. Chemists have learned how to obtain refractory, heat-resistant, chemically resistant, high-hard ceramics, as well as ceramics for electrical engineering. Recently, an amazing property of some ceramic products has been discovered to have high-temperature superconductivity, i.e. superconductivity at temperatures above the boiling point of nitrogen. The discovery of this unique physical property was facilitated by the work of chemists on the creation of new ceramics based on complexes with barium, lanthanum and copper, taken in a single complex.

The chemistry of organoelement materials using silicon (organosilicon chemistry) underlies the creation of the production of many polymers that have valuable properties and are indispensable in aviation and energy. And organofluorine compounds are exceptionally stable (even in acids and alkalis) and have a special surface activity and therefore can carry, for example, oxygen like a hemoglobin molecule! Organofluorine compounds are actively used in medicine to create all kinds of coatings, etc.

The solution of practical problems facing chemists at the present time is associated with the synthesis of new substances and the analysis of their chemical composition. Therefore, as many years ago, the problem of the composition of substances remains relevant in chemistry.

The second stage in the development of chemistry as a science - XIX century: Structural chemistry.

In 1820 - 1830. the manufactory stage of production with its manual technique was replaced by the factory stage. New machines appeared in production, there was a need to search for new raw materials for use in industry. In chemical production, the processing of huge masses of substances of plant and animal origin began to prevail, the qualitative variety of which was amazingly great, and the composition was uniform: carbon, hydrogen, oxygen, sulfur, nitrogen, phosphorus. This means that the properties of substances are determined not only by the composition - the chemists concluded.

Chemists have found that the properties of substances, and hence their qualitative diversity, are determined not only by their composition, but also by the structure of molecules. If knowledgecomposition of matter answers the question of what chemical elements the molecule of a given substance consists of, That knowledgestructure of matter gives an idea of the spatial arrangement of atoms in this very molecule.

At the same time, it became clear that not all atoms that make up the molecule of a given substance interact equally well with atoms of other molecules. Each molecule can be conditionally subdivided into several so-called functional or reactive units, which include groups of atoms, just individual atoms, or even individual chemical bonds. Each of these structures has its own unique ability to enter into chemical reactions, i.e. hisreactivity .

The second level of development of chemical knowledge received the conditional name structural chemistry .The main achievement of this stage could be called the establishment of a relationship between the structure of the molecule and the functional activity of the compound:

STRUCTURE OF A MOLECULE ---> FUNCTION (REACTIVITY)

Thus, knowledge of the structure of molecules transferred chemistry to the second level of development of chemical knowledge and contributed to the transformation of chemistry from predominantly analytical science to science synthetic . There was also organic matter technology which did not exist before.

The evolution of the concept of "structure" in chemistry. According to the theory put forward J. Dalton, any chemical substance is a collection of molecules that have a strictly defined qualitative and quantitative composition, i.e., consisting of a certain number of atoms of one, two or three chemical elements. The theory of the structure of matter by J. Dalton answered the question: how to distinguish individual substances from mixtures of substances, but it did not answer many other questions: how do atoms combine into a molecule, is there any order in the arrangement of atoms in a molecule, or are they combined haphazardly, by chance?

The Swedish chemist tried to answer these questions AND I. Berzelius who lived in the first half of the 19th century. I. Ya. Berzelius believed that a molecule is not a simple heap of atoms, but a certain ordered structure of atoms interconnected by electrostatic forces. He proposed a new atom model as electric dipole . AND I. Berzelius put forward the hypothesis that all atoms of different chemical elements have different electronegativity and arranged them in a kind of row as it increases.

N. B! AND I. Berzelius, based on the determination of the percentage composition of many substances given by him and the search for elementary stoichiometric patterns, as well as studying the decomposition of complex substances in solution under the action of an electric current, asked the question: what affects the sign and magnitude of the electric charge of a particular substance? Why are there electropositive and electronegative substances? What is the difference in the structure of the molecules of an acid and an alkali, or an alkali and a neutral salt?

In 1840, in the works of the French scientist C. Gerard it was shown that the structures of I. Ya. Berzelius are not valid in all cases: there is a mass of substances whose molecules cannot be decomposed into individual atoms under the influence of an electric current, they represent, as it were, a single whole system and just such indivisible system of interconnected atoms C. Gerard and proposed to call molecule . He developed the theory of types of organic compounds.

In 1857 a German chemist A. Kekule published his observations on the properties of individual elements that can replace hydrogen atoms in a number of compounds. He came to the conclusion that some of them can replace three hydrogen atoms, while others - only two or even one. A. Kekule also found that "one carbon atom ... is equivalent to four hydrogen atoms." These were the fundamentals theories of valency of substances .

A. Kekule introduced a new chemical term affinity , which denoted the number of hydrogen atoms that a given chemical element can replace. He assigned three, two, or one unit of affinity to all elements, respectively. At the same time, carbon was in an unusual position - its atom had four units of affinity. The number of units of affinity inherent in a given chemical element, the scientist calledatom valency .

When atoms combine into a molecule, free affinity units are closed.

concept molecular structure with the light hand of A. Kekule, it was reduced to the construction of visual formula schemes that served as a guide for chemists in their practical work, a specific indication of which starting substances should be taken in order to obtain the necessary chemical product.

N. B! A. Kekule's schemes, however, could not always be implemented in practice: a well-thought-out (or invented) reaction did not want to proceed according to a beautiful scheme. This happened because formula schematism did not take into account the reactivity of substances that enter into chemical interaction with each other.

Answers to the questions of concern to practical chemists were given by the theory chemical structure Russian scientist Alexander Mikhailovich Butlerov. Butlerov, like Kekule, recognized that the formation of molecules from atoms occurs due to the closure of free units of affinity, but at the same time he pointed out the importance of what “tension, greater or lesser energy (this affinity) binds substances together ".

The theory of A. M. Butlerov became a guide for chemists in their practical activities. Later, it found its confirmation and physical justification in quantum mechanics.

chemical bond. A chemical bond is the interaction between the atoms of elements, causing their combination into molecules and crystals.

The type of bond is determined by the nature of the physical interaction of atomic-molecular particles with each other. The fundamental theory of chemical bonds was created in the 30s of the twentieth century by an American chemist Linus Pauling.

At present, the concept of "chemical bond" has become broader . Now under chemical bond understood as such a type of interaction not just between individual atoms, but sometimes between atomic and molecular particles, which is due to the joint use of their electrons. Here it is understood that such socialization of electrons by interacting particles can vary over a wide range. Exist covalent (polar, non-polar), hydrogen and ionic (ionic-covalent) bonds, as well as metallic bonds.

Ionic bond is formed when, uniting into one molecule, one of the atoms loses electrons from its outer shell (cation), and the other acquires them (anion), oppositely charged ions are attracted to each other, forming strong bonds. Ionic compounds are generally solids with a very high melting point (salts, alkalis, e.g. table salt).

covalent bond is formed as a result of an electron pair belonging simultaneously to both atoms that create a molecule of a substance. Since such molecules are held by weak forces, they are unstable and exist as liquids or gases with low melting and boiling points (oxygen, butane).

The hydrogen bond is due to the polarization of covalent bonds, when joint electrons most of the time are at the atom of the element associated with the hydrogen atom. As a result, such an atom receives a small negative charge, which makes compounds with hydrogen bonds stronger than other covalent compounds (water).

Metallic bonds are due to the free movement of electrons in the outer shells of metal atoms. Atoms in metals line up in precisely matched rows, held together by an electronic field.

Thanks to the development of structural representations in 1860-1880. the term appeared in chemistry organic synthesis , denoting not only actions to obtain new organic substances, but also a whole field of science, so named in contrast to the general enthusiasm for the analysis of natural substances.

So under valency of atomic particles understood them the property to enter into a chemical interaction, the quantitative measure of which is the total number of unpaired electrons, lone electron pairs and vacant orbitals involved in the formation of chemical bonds. The valence of an atomic particle is not a constant value and can vary from unity to a certain maximum value depending on the nature of the partner particles and the conditions for the formation of a chemical compound.

Under the concept structure understand stable ordering of a qualitatively unchanged system.

Under molecular structure understand a combination of a limited number of atoms that have a regular arrangement in space and are chemically bonded to each other using valence electrons. The molecular structure is divided into nuclear (geometric) and electronic .

In the first approximation under atomic structure should be understood a stable collection of the nucleus and the electrons surrounding it, which are in electromagnetic interaction with each other.

The third stage in the development of chemistry as a science - the first half of the XX century: The doctrine of chemical processes - kinetic chemistry.

In connection with the development of technology and precisely at this time, chemistry becomes a science not only and not so much about substances, but a science about the processes and mechanisms of change in substances.

The intensive development of the automotive industry, aviation, energy and instrumentation at the beginning of our century required high-quality fuel for the operation of engines. Special high-strength rubbers for car tires, plastics to lighten their weight, all kinds of polymers and semiconductors - all this had to be obtained in large quantities, but, alas, the development of chemical skills did not meet the demands of production.

The fact is that the chemical reaction itself is a rather capricious thing. The interaction of substances during the reaction leads to a change in the composition of the substance. To do this, one combination of atoms must be destroyed and another created. To destroy the old connection, it is necessary to expend energy. The formation of a new compound is usually accompanied by the release of energy.

Chemical reactions are described by equations based onlaw of conservation of matter . According to this law, the total mass of substances that have entered into a reaction must exactly correspond to the mass of the formed substances. For mass calculations, a counting unit is used - mol, contains the same number of particles (6 10 23, Avogadro's number)

The doctrine of chemical processes. Methods of chemical process control. The doctrine of chemical processes is such a field of science in which there is the deepest interpenetration of physics, chemistry and biology. At the heart of this doctrine are chemical thermodynamics and kinetics , therefore, all this doctrine of chemical processes applies equally to both chemistry and physics.

There are a large number of problems to be solved in connection with the creation of the doctrine of chemical processes. A detailed description of them can be found in any modern textbook on physical chemistry. But, perhaps, one of the most basic problems was the task of creating methods to control chemical processes.

In the very general view All control methods can be divided into two large groups: thermodynamic and kinetic. The first group - thermodynamic methods - This methods affecting offset chemical equilibrium reactions; second group - kinetic methods -These are methods that affect the rate of a reaction.

In 1884, a book by an outstanding Dutch chemist appeared I. van't Hoff, in which he substantiated the laws establishing the dependence of the direction of a chemical reaction on changes in temperature and the thermal effect of the reaction. In the same year, the French chemist A. Le Chatelier formulated his famous principle of moving balance , having armed chemists with methods of shifting the equilibrium towards the formation of reaction products. In this case, the main control levers were temperature, pressure and concentration reactants. Therefore, these control methods got their name - thermodynamic .

Remember that any chemical reaction is reversible. For example, a reaction like:

AB+CD<=>AC+BD

Reversibility of reactions serves as the basis for the balance between forward and reverse reactions. In practice, the balance shifts in one direction or another. In order for the chemical reaction to go in the direction of increasing the reaction products AC and BD, it is necessary either to increase the concentration of substances AB and CD, or to change the temperature or pressure.

But thermodynamic methods only allowed to control direction reactions, not their rates. speed controlchemical reactions depending on various factors, a special science is engaged - chemical kinetics . A lot of things can affect the rate of a chemical reaction, even the walls of the vessel in which the reaction takes place.

The third way to solve the main problem, taking into account the complexity of the organization of chemical processes and providing an economically acceptable performance of these processes in chemical reactors, can be represented by the scheme:

CHEMICAL ORGANIZATION ---> PERFORMANCE

PROCESSES IN THE REACTOR REACTOR

Catalysis and chemistry of extreme states. In 1812, a Russian academician K.S. Kirchhoff phenomenon was discovered chemical catalysis .Catalysisis the most common and widespread way of carrying out chemical reactions, the peculiarity of which is the activation of reagent molecules upon contact with a catalyst. In this case, there is a kind of "relaxation" of chemical bonds in the original substance, "pulling" it into separate parts, which then more easily interact with each other.

Unsteady kinetics. Development of ideas about the evolution of systems. In the 1970s, many chemical systems were discovered that used catalysts, in which, over time, everything happened the other way around - the process did not stabilize as usual, but became non-stationary . Several types have been discovered self-oscillating chemical reactions , in which periodic changes in the yield of reaction products occur over time. In other words, the necessary product of a chemical reaction is either released in large quantities, or, on the contrary, the reaction almost does not proceed or even changes its direction, and then all this is repeated again. It turned out that in a number of cases the total amount of the substance obtained in the course of such unstable chemical reaction, even exceeds the amount of substance that would be released during the reaction if it took place stationary or, i.e. would have constant speed .

Studying non-stationary kinetics started recently. But there are already practical results. With its help, some energetically coupled processes were investigated, i.e. such chemical processes in which several reactions take part at once, exchanging energy with each other. Non-stationary chemical processes have also been discovered in wildlife.

The fourth stage in the development of chemistry as a science - the second half of the 20th century: Evolutionary chemistry. In 1960 - 1979, a new way to solve the basic problem of chemistry appeared, which was called evolutionary chemistry . This method is based on the principle of using in the processes of obtaining chemical products such conditions that lead to self-improvement of catalysts for chemical reactions, i.e. to the self-organization of chemical systems.

Thus, the fourth stage in the development of chemistry, which continues to the present, establishes a connection between the self-organization of a system of reagents and the behavior of this system:

SELF-ORGANIZING -----> REAGENT SYSTEM BEHAVIOR REAGENT SYSTEM

Evolutionary problems of chemistry. Start evolutionary chemistry associated with 1950-1960. Under evolutionary problems should be understood problems of synthesis of new complex, highly organized compounds without human intervention.

The theory of chemical evolution and biogenesis A.P. Rudenko. In the 1960s, cases of self-improvement of some chemical catalysts during a chemical reaction were noted. Conventional catalysts eventually (like everything in the world) age and wear out. But chemists managed to find such catalysts that not only did not age, but, on the contrary, "rejuvenated" with each chemical reaction. The answer to this question was attempted to be given by the theory of chemical evolution and biogenesis proposed by scientists of the world in 1964 as a Russian professor A. P. Rudenko. The essence of this theory is that chemical evolution is self-development of catalytic systems . During the reaction, the selection of those catalytic centers that have the highest activity occurs (the main law of chemical evolution): Evolutionary changes in the catalyst occur in the direction where its maximum activity is manifested. Self-development of systems occurs due to the constant absorption by catalysts of the energy flow that is released during the chemical reaction itself, therefore, catalytic systems with higher energy evolve. Such systems destroy the chemical equilibrium and, as a result, serve as a tool for selecting the most stable evolutionary changes in the catalyst.

The study of the structure and functioning of enzymes in wildlife is such a stage of chemical knowledge that will open up the creation of fundamentally new chemical technologies in the future.

Despite the fact that chemistry is currently still far from the perfection that the “laboratory of a living organism” possesses, the paths to this ideal are outlined. Today, chemists have come to the conclusion that using the same principles on which the chemistry of living organisms is built, in the future (without exactly repeating nature) it will be possible to “build” a fundamentally new chemistry, a new control of chemical processes - just as it happens in any living cell . Chemists hope to obtain a new generation of catalysts that would make it possible to create, for example, unusual solar light converters.

Scientists strive to create industrial analogues of chemical processes occurring in wildlife. They study the experience of biochemical catalysts and create such catalysts in the laboratory. The particular difficulty of working with biochemical catalysts - enzymes , is the fact that they are very unstable during storage and quickly deteriorate, losing their activity. Therefore, chemists have been working for a long time on the creation of enzyme stabilization, and as a result they have learned how to obtain the so-called immobilized enzymes - This enzymes isolated from a living organism and attached to a solid surface by their adsorption. Such biocatalysts are very stable and stable in chemical reactions and can be used repeatedly. founder chemistry of immobilized systems is a Russian chemist I. V. Berezin.

Among promising directions Chemistry of the 21st century is of particular interest to:

brain chemistry

Earth macrochemistry

coherent chemistry

Spin chemistry and chemical radiophysics

Chemistry of Extreme States

cold fusion

Physics of chemical reactions.

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higher professional education

Penza State University

Department of Zoology and Ecology

Abstract on the topic: “Chemical picture of the world. Stages of development"

Performed:

Shkutova Olesya Olegovna

Reviewer:

cand. biol. Sciences, Associate Professor - Ilyina N.L.

1. The main stages in the development of chemistry

The history of chemistry studies and describes the complex process of accumulation of specific knowledge related to the study of the properties and transformations of substances; it can be viewed as a border area of knowledge that links the phenomena and processes related to the development of chemistry with the history of human society. When studying the history of the development of chemistry, two mutually complementary approaches are possible: chronological and meaningful.

With a chronological approach, the history of chemistry is usually divided into several periods. It should be taken into account that the periodization of the history of chemistry, being rather conditional and relative, has more of a didactic meaning. At the same time, at the later stages of the development of science (in the case of chemistry, already from early XIX centuries) due to its differentiation, deviations from the chronological order of presentation are inevitable, since it is necessary to separately consider the development of each of the main sections of science.

As a rule, most historians of chemistry distinguish the following main stages of its development:

1. Pre-alchemical period: until the III century. AD

In the pre-alchemical period, the theoretical and practical aspects of knowledge about matter developed relatively independently of each other. The origin of the properties of a substance was considered by ancient natural philosophy, practical operations with a substance were the prerogative of handicraft chemistry.

2. Alchemical period: III - XVII centuries.

The alchemical period, in turn, is divided into three sub-periods - Alexandrian (Greco-Egyptian), Arabic and European alchemy. The alchemical period is the time of the search for the philosopher's stone, which was considered necessary for the implementation of the transmutation of metals. In this period, the birth of experimental chemistry and the accumulation of a stock of knowledge about matter took place; alchemical theory, based on ancient philosophical ideas about the elements, was closely connected with astrology and mysticism. Along with chemical-technical "gold-making", the alchemical period is also notable for the creation of a unique system of mystical philosophy.

3. The period of formation (association): XVII - XVIII centuries.

During the formation of chemistry as a science, its complete rationalization took place. Chemistry freed itself from the natural-philosophical and alchemical views of the elements as carriers of certain qualities. Along with the expansion of practical knowledge about matter, a unified view of chemical processes began to be developed and the experimental method began to be fully used. completed this period chemical revolution finally gave chemistry the appearance of an independent (albeit closely related to other branches of natural science) science, engaged in the experimental study of the composition of bodies.

4. The period of quantitative laws (atomic-molecular theory): 1789 - 1860.

The period of quantitative laws, marked by the discovery of the main quantitative laws of chemistry - stoichiometric laws, and the formation of the atomic-molecular theory, finally completed the transformation of chemistry into an exact science based not only on observation, but also on measurement.

5. The period of classical chemistry: 1860 - the end of the 19th century *

The period of classical chemistry is characterized rapid development sciences: were created periodic system elements, theory of valency and chemical structure of molecules, stereochemistry, chemical thermodynamics and chemical kinetics; Applied inorganic chemistry and organic synthesis achieved brilliant successes. In connection with the growth in the volume of knowledge about matter and its properties, the differentiation of chemistry began - the allocation of its separate branches, acquiring the features of independent sciences.

Most textbooks and teaching aids when considering the periodization of the history of chemistry, the period of quantitative laws is followed by the modern period. However, according to the author, this is not entirely correct, because at the beginning of the 20th century. The theoretical foundations of chemistry have undergone significant changes. Second half of the 19th century is an extremely important special stage in the development of chemical knowledge. During this period, the atomic-molecular theory and the doctrine of chemical elements, the classical sections of chemistry, are finally formed, periodic law, there are two new conceptual systems of chemistry - structural chemistry and the doctrine of the chemical process.

6. Modern period: from the beginning of the 20th century to the present

At the beginning of the 20th century, there was a revolution in physics: the system of knowledge about matter based on Newtonian mechanics was replaced by quantum theory and the theory of relativity. The establishment of the divisibility of the atom and the creation of quantum mechanics have invested new content in the basic concepts of chemistry. The advances in physics at the beginning of the 20th century made it possible to understand the reasons for the periodicity of the properties of elements and their compounds, to explain the nature of valence forces, and to create theories of the chemical bond between atoms. The emergence of fundamentally new physical methods research has provided chemists with unprecedented opportunities to study the composition, structure and reactivity of matter. All this together determined, among other achievements, the brilliant successes of biological chemistry in the second half of the 20th century - the establishment of the structure of proteins and DNA, the knowledge of the mechanisms of functioning of the cells of a living organism.

2. Conceptual Systems of Chemistry

A meaningful approach to the history of chemistry is based on the study of how the theoretical foundations of science have changed over time. Due to changes in theories throughout the existence of chemistry, its definition has constantly changed. Chemistry originates as "the art of transforming base metals into noble ones"; Mendeleev in 1882 defines it as "the doctrine of the elements and their compounds." The definition from a modern school textbook, in turn, differs significantly from Mendeleev's: "Chemistry is the science of substances, their composition, structure, properties, mutual transformations and the laws of these transformations."

It should be noted that the study of the structure of science does little to create an idea of the development of chemistry as a whole: the generally accepted division of chemistry into sections is based on a number of different principles. The division of chemistry into organic and inorganic is based on the difference between their subjects (which difference, by the way, can only be correctly understood by historical consideration). The allocation of physical chemistry is based on its proximity to physics, analytical chemistry is distinguished on the basis of the research method used. In general, the generally accepted division of chemistry into sections is largely a tribute to historical tradition; each section intersects with all the others to some extent.

The main task of a meaningful approach to the history of chemistry is, in the words of D. I. Mendeleev, the selection of "the unchanging and general in the changeable and particular." So unchanging and common to the chemical knowledge of all historical periods is the goal of chemistry. It is the goal of science - not only theoretical, but also its historical core.

The goal of chemistry at all stages of its development is to obtain a substance with desired properties. This goal, sometimes called the basic problem of chemistry, includes two important tasks - practical and theoretical, which cannot be solved separately from each other. Obtaining a substance with desired properties cannot be carried out without identifying ways to control the properties of the substance, or, what is the same, without understanding the causes of the origin and conditionality of the properties of the substance. Thus, chemistry is both an end and a means, both theory and practice.

The theoretical problem of chemistry has a limited and strictly defined number of ways to solve, which are given by the structural hierarchy of the substance itself, for which the following levels of organization can be distinguished:

1. Subatomic particles.

2. Atoms of chemical elements.

3. Molecules of chemicals as unitary (single) systems.

4. Micro- and macroscopic systems of reacting molecules.

5. Megasystems ( solar system, Galaxy, etc.)

The objects of study of chemistry is the substance at 2 - 4 levels of organization. Based on this, in order to solve the problem of the origin of properties, it is necessary to consider the dependence of the properties of a substance on three factors:

1. From elemental composition;

2. From the structure of the substance molecule;

3. From the organization of the system.

Thus, the hierarchy of the studied material objects predetermines the hierarchy of the so-called. conceptual systems of chemistry - relatively independent systems of theories and methodological principles used to describe and study the properties of matter at any level of organization. Three conceptual systems are usually distinguished, namely:

1. The doctrine of the composition;

2. Structural chemistry;

3. The doctrine of the chemical process.

The doctrine of composition arose much earlier than the other two conceptual systems - already in ancient natural philosophy, the concept of elements as constituent parts of bodies appears. Scientific chemistry perceives this doctrine, but already based on fundamentally new ideas about the elements, as about bodies (particles) that are further indecomposable, of which all "mixed bodies" (compounds) are composed. The main thesis of the doctrine of composition is as follows: the properties of a substance are determined by its composition, i.e. by what elements and in what proportion of them a given substance is formed. The object of the doctrine of composition is matter as a collection of atoms. alchemical atomic molecular

Structural chemistry, which appeared in the first half of the 19th century, proceeds from the following thesis: the properties of a substance are determined by the structure of the molecule of the substance, i.e. its elemental composition, the order in which atoms are connected to each other and their arrangement in space. The reason for the emergence of structural chemistry was the discovery of the phenomena of isomerism and metalepsy (see Ch. 5.2.), which could not be explained within the framework of existing concepts. New theories are proposed to explain these experimental facts; the object of structural chemistry becomes a molecule chemical as a whole. With regard to chemical practice, the emergence of a new conceptual system meant in this case also the transformation of chemistry from a predominantly analytical science into a synthetic science.

The doctrine of the chemical process, which was formed in the second half of the 19th century, proceeds from the premise that the properties of a substance are determined by its composition, structure and organization of the system in which this substance is located. The doctrine of the process is separated into an independent concept of chemistry, when experimental facts accumulate, indicating that the laws governing chemical reactions, cannot be reduced to the composition of the substance and the structure of its molecule. Knowledge of the composition of a substance and the structure of molecules is often not enough to predict the properties of a substance, which in the general case are also determined by the nature of co-reagents, relative quantities reagents, external conditions in which the system is located, the presence in the system of substances that are not stoichiometrically involved in the reaction (impurities, catalysts, solvent, etc.). The subject of study of chemistry at this level is the whole kinetic system, in which the composition of the substance and the structure of its molecules are presented only as particulars. The empirical concepts of chemical affinity and reactivity are theoretically substantiated in chemical thermodynamics, chemical kinetics, and the theory of catalysis. The creation of the doctrine of the chemical process made it possible to solve the most important practical problems of controlling chemical transformations, to introduce fundamentally new processes into chemical technology.

Sometimes another conceptual system stands out - evolutionary chemistry, which, according to the supporters of this approach, is the doctrine of higher forms of chemism and the chemical evolution of matter. Evolutionary chemistry studies the processes of self-organization of matter: from atoms and simple molecules to living organisms.

Thus, within the framework of a meaningful approach, the history of chemistry can be considered as the history of the emergence and development of conceptual systems, each of which is fundamentally new way solution of the main problem of chemistry. It should be noted that these conceptual systems do not contradict each other and do not replace one another, but are mutually complementary.

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