Interesting tasks on the topic of the chemical picture of the world. Philosophical problems of the chemical picture of the world

The origins of chemical knowledge lie in ancient times. They are based on the human need to obtain the necessary substances for their life. The origin of the term "chemistry" has not yet been clarified, although there are several versions on this issue. According to one of them, this name comes from the Egyptian word "chemi", which meant Egypt, and also "black". Historians of science also translate this term as "Egyptian art." Thus, in this version, the word chemistry means the art of producing the necessary substances, including the art of turning ordinary metals into gold and silver or their alloys.

However, another explanation is now more popular. The word "chemistry" comes from the Greek term "chymos", which can be translated as "plant juice". Therefore, "chemistry" means "the art of making juices," but the juice in question could also be molten metal. So chemistry can also mean "the art of metallurgy."

The history of chemistry shows that its development was uneven: periods of accumulation and systematization of data from empirical experiments and observations were replaced by periods of discovery and heated discussion of fundamental laws and theories. The successive alternation of such periods makes it possible to divide the history of chemical science into several stages.

The main periods in the development of chemistry

1. Alchemy Period- from antiquity to the 16th century. ad. It is characterized by the search for the philosopher's stone, the elixir of longevity, the alkahest (universal solvent). In addition, during the alchemical period, almost all cultures practiced the “transformation” of base metals into gold or silver, but all these “transformations” were carried out by each people in a variety of ways.

2. The period of the birth of scientific chemistry, which lasted during the XVI - XVIII centuries. At this stage, the theories of Paracelsus, the theories of gases by Boyle, Cavendish, and others, the theory of phlogiston by G. Stahl, and, finally, the theory of chemical elements by Lavoisier were created. During this period, applied chemistry was improved, associated with the development of metallurgy, the production of glass and porcelain, the art of distillation of liquids, etc. By the end of the 18th century, chemistry was consolidated as a science independent of other natural sciences.

3. Period of discovery of the basic laws of chemistry covers the first sixty years of the 19th century and is characterized by the emergence and development of Dalton's atomic theory, Avogadro's atomic-molecular theory, the establishment of the atomic weights of elements by Berzelius and the formation of the basic concepts of chemistry: atom, molecule, etc.

4. Modern period lasts from the 60s of the XIX century to the present day. This is the most fruitful period in the development of chemistry, since in a little over 100 years the periodic classification of elements, the theory of valency, the theory of aromatic compounds and stereochemistry, the Arrhenius theory of electrolytic dissociation, the electronic theory of matter, etc. have been developed.

At the same time, during this period, the range of chemical research was significantly expanded. Such components of chemistry as inorganic chemistry, organic chemistry, physical chemistry, pharmaceutical chemistry, food chemistry, agrochemistry, geochemistry, biochemistry, etc., have acquired the status of independent sciences and their own theoretical base.

Alchemy Period

Historically alchemy It was formed as a secret, mystical knowledge aimed at searching for the philosopher's stone, which turns metals into gold and silver, and the elixir of longevity. During its centuries-old history, alchemy solved many practical problems related to obtaining substances and laid the foundation for the creation of scientific chemistry.

Alchemy reached its highest development in three main types:

Greco-Egyptian

· Arabic;

Western European.

The birthplace of alchemy is Egypt. Even in ancient times, there were known methods for obtaining metals, alloys used for the production of coins, weapons, and jewelry. This knowledge was kept secret and was the property of a limited circle of priests. The growing demand for gold prompted metallurgists to look for ways to convert (transmute) base metals (iron, lead, copper, etc.) into gold. The alchemical nature of ancient metallurgy connected it with astrology and magic. Each metal had an astrological connection with the corresponding planet. The pursuit of the philosopher's stone made it possible to deepen and expand knowledge of chemical processes. Metallurgy was developed, and the processes for refining gold and silver were improved. However, during the reign of Emperor Diocletian in ancient Rome, alchemy began to be persecuted. The possibility of obtaining cheap gold frightened the emperor and, on his orders, all works on alchemy were destroyed. A significant role in the prohibition of alchemy was played by Christianity, which considered it as a diabolical craft.

After the Arab conquest of Egypt in the 7th c. n. e. alchemy began to develop in the Arab countries. The most famous Arab alchemist was Jabir ibn Khayyam, known in Europe as Geber. He described ammonia, the technology for preparing white lead, and the method of distilling vinegar to obtain acetic acid. Jabir's fundamental idea was the theory of the formation of all the then known seven metals from a mixture of mercury and sulfur as the two main components. This idea anticipated the division of simple substances into metals and non-metals.

The development of Arabic alchemy followed two parallel paths. Some alchemists were engaged in the transmutation of metals into gold, others were looking for the elixir of life, which gave immortality.

The emergence of alchemy in Western Europe became possible thanks to the Crusades. Then the Europeans borrowed scientific and practical knowledge from the Arabs, among which was alchemy. European alchemy came under the protection of astrology and therefore acquired the character of a secret science. The name of the most prominent medieval Western European alchemist remained unknown, it is only known that he was a Spaniard and lived in the XIV century. He was the first to describe sulfuric acid, the process of formation of nitric acid, aqua regia. The undoubted merit of European alchemy was the study and production of mineral acids, salts, alcohol, phosphorus, etc. Alchemists created chemical equipment, developed various chemical operations: heating over direct fire, water bath, calcination, distillation, sublimation, evaporation, filtering, crystallization, etc. Thus, appropriate conditions were prepared for the development of chemical science.

2. The period of the birth of chemical science covers three centuries: from the 16th to the 19th centuries. The conditions for the formation of chemistry as a science were:

Ø renewal of European culture;

Ø the need for new types of industrial production;

Ø discovery of the New World;

Ø Expansion of trade relations.

Separated from the old alchemy, chemistry acquired greater freedom of research and established itself as a single independent science.

In the XVI century. alchemy was replaced by a new direction, which was engaged in the preparation of medicines. This direction is called iatrochemistry . The founder of iatrochemistry was a Swiss scientist Theophrastus Bombast von Hohenheim, known in science as Paracelsus.

Iatrochemistry expressed the desire to combine medicine with chemistry, overestimating the role of chemical transformations in the body and attributing to certain chemical compounds the ability to eliminate imbalances in the body. Paracelsus firmly believed that if the human body consists of special substances, then the changes occurring in them should cause diseases that can only be cured by the use of drugs that restore normal chemical balance. Before Paracelsus, medicines were predominantly herbal preparations, but he relied only on the effectiveness of medicines made from minerals, and therefore sought to create medicines of this type.

In his chemical research, Paracelsus borrowed from the alchemical tradition the doctrine of the three main constituents of matter - mercury, sulfur and salt, which correspond to the basic properties of matter: volatility, combustibility and hardness. These three elements form the basis of the macrocosm (universe), but they also refer to the microcosm (man), consisting of the spirit, soul and body. Determining the causes of diseases, Paracelsus argued that fever and plague come from an excess of sulfur in the body, with an excess of mercury, paralysis occurs, and an excess of salt can cause indigestion and dropsy. In the same way, he attributed the causes of many other diseases to an excess or deficiency of these three basic elements.

In the preservation of human health, Paracelsus attached great importance to chemistry, since he proceeded from the observation that medicine rests on four pillars, namely philosophy, astrology, chemistry and virtue. Chemistry must develop in harmony with medicine, because this union will lead to the progress of both sciences.

Iatrochemistry brought significant benefits to chemistry, as it helped to free it from the influence of alchemy and significantly expanded knowledge about vital compounds, thereby having a beneficial effect on pharmacy. But at the same time, iatrochemistry was also an obstacle to the development of chemistry, because it narrowed the field of its research. For this reason, in the XVII and XVIII centuries. a number of researchers abandoned the principles of iatrochemistry and chose a different path for their research, introducing chemistry into life and putting it at the service of man.

It was these researchers who, with their discoveries, contributed to the creation of the first scientific chemical theories.

Phlogiston's theory

Long before the 18th century, Greek and Western alchemists tried to answer these questions: Why do some things burn while others don't? What is the combustion process?

According to the ideas of the ancient Greeks, everything that is capable of burning contains the element of fire, which, under appropriate conditions, can be released. Alchemists adhered to approximately the same point of view, but believed that substances capable of burning contain the element "sulphur". In 1669 German chemist Johann Becher tried to give a rational explanation for the phenomenon of flammability. He suggested that solids were composed of three kinds of "earth", and one of these kinds, which he called "fatty earth", served as a combustible substance. All these explanations did not answer the question about the essence of the combustion process, but they became the starting point for the creation of a unified theory, known as the theory of phlogiston.

Instead of Becher's concept of "fat earth", Stahl introduced the concept of "phlogiston" - from the Greek "phlogistos" - combustible, flammable. The term "phlogiston" became widespread due to the work of Stahl himself and because his theory combined numerous information about combustion and roasting.

The phlogiston theory is based on the belief that all combustible substances are rich in a special combustible substance - phlogiston, and the more phlogiston a given body contains, the more it is capable of burning. What remains after the completion of the combustion process does not contain phlogiston and therefore cannot burn. Stahl argues that the melting of metals is like burning wood. Metals, in his opinion, also contain phlogiston, but, losing it, they turn into lime, rust or scale. However, if phlogiston is again added to these residues, then again metals can be obtained. When these substances are heated with coal, the metal is "reborn".

This understanding of the melting process made it possible to give an acceptable explanation for the process of turning ores into metals - the first theoretical discovery in the field of chemistry.

Stahl's theory of phlogiston met with sharp criticism at first, but at the same time it quickly began to gain popularity in the second half of the 17th century. was accepted by chemists everywhere, as it allowed to give clear answers to many questions. However, neither Stahl nor his followers could resolve one issue. The fact is that most combustible substances (wood, paper, fat) largely disappeared during combustion. The remaining ash and soot were much lighter than the original substance. But the chemists of the XVIII century. this problem did not seem important, they did not yet realize the importance of accurate measurements, and they neglected the change in weight. The phlogiston theory explained the reasons for the change in the appearance and properties of substances, and changes in weight were unimportant.

The influence of the ideas of A.L. Lavoisier on the development of chemical knowledge

By the end of the XVIII century. in chemistry, a large amount of experimental data was accumulated, which needed to be systematized within the framework of a unified theory. The creator of such a theory was the French chemist Antoine-Laurent Lavoisier.

From the very beginning of his activity in the field of chemistry, Lavoisier understood the importance of accurately measuring the substances involved in chemical processes. The use of precise measurements in the study of chemical reactions allowed him to prove the inconsistency of the old theories that hindered the development of chemistry.

The question of the nature of the combustion process was of interest to all chemists of the 18th century, and Lavoisier also could not help being interested in it. His numerous experiments on heating various substances in closed vessels made it possible to establish that, regardless of the nature of chemical processes and their products, the total weight of all substances participating in the reaction remains unchanged.

This allowed him to put forward a new theory of the formation of metals and ores. According to this theory, the metal in the ore is combined with gas. When ore is heated on charcoal, the charcoal absorbs the gas from the ore and carbon dioxide and metal are formed.

Thus, unlike Stahl, who believed that the smelting of metal involved the transfer of phlogiston from charcoal to ore, Lavoisier imagines this process as the transfer of gas from ore to coal. Lavoisier's idea made it possible to explain the reasons for the change in the weight of substances as a result of combustion.

Considering the results of his experiments, Lavoisier came to the conclusion that if we take into account all the substances involved in the chemical reaction and all the products formed, then there will never be a change in weight. In other words, Lavoisier came to the conclusion that mass is never created or destroyed, but only passes from one substance to another. This conclusion, known today as the law of conservation of mass, became the basis for the entire development of chemistry in the 19th century.

However, Lavoisier himself was dissatisfied with the results obtained, because he did not understand why scale was formed when air was combined with metal, and gases were formed when combined with wood, and why not all air, but only about a fifth of it, participated in these interactions?

Again, as a result of numerous experiments and experiments, Lavoisier came to the conclusion that air is not a simple substance, but a mixture of two gases. One fifth of the air, according to Lavoisier, is "dephlogisticated air", which combines with burning and rusting objects, passes from ores to charcoal and is necessary for life. Lavoisier called this gas oxygen, that is, generating acids, since he mistakenly believed that oxygen is a component of all acids.

The second gas, which is four-fifths of the air ("phlogisticated air"), was recognized as a completely independent substance. This gas did not support combustion, and Lavoisier called it nitrogen - lifeless.

An important role in Lavoisier's research was played by the results of the experiments of the English physicist Cavendish, who proved that the gases formed during combustion condense into a liquid, which, as the analyzes showed, is only water.

The importance of this discovery was enormous, since it turned out that water is not a simple substance, but a product of the combination of two gases.

Lavoisier called the gas released during combustion hydrogen (“forming water”) and noted that hydrogen burns by combining with oxygen, and therefore water is a combination of hydrogen and oxygen.

Lavoisier's new theories brought about a complete rationalization of chemistry. It was finally finished with all the mysterious elements. Since that time, chemists have become interested only in those substances that can be weighed or measured in some other way.

Chemistry- the science of the transformations of substances, accompanied by a change in their composition and structure.

Phenomena in which one substance forms another is called chemical. Naturally, on the one hand, these phenomena can be found purely physical changes, but on the other hand, chemical phenomena are always present in all biological processes. Thus, it is obvious connection chemistry with physics and biology.

This connection, apparently, was one of the reasons why chemistry could not become an independent science for a long time. Although already Aristotle divided substances into simple and complex, pure and mixed, and tried to explain the possibility of some transformations and the impossibility of others, chemical phenomena as a whole, he considered quality changes and therefore attributed to one of the genera movements. Chemistry Aristotle was part of it physics- knowledge about nature ().

Another reason for the dependence of ancient chemistry is connected with theoretical, the contemplativeness of all ancient Greek science as a whole. In things and phenomena they were looking for the unchanging - idea. Theory chemical phenomena led to element idea() as a certain beginning of nature or to idea of the atom as an indivisible particle of matter. According to the atomistic concept, the features of the forms of atoms in the multitude of their combinations determine the diversity of the qualities of the bodies of the macrocosm.

Empirical experience belonged in ancient Greece to the area arts and crafts. It also included practical knowledge about chemical processes: smelting metals from ores, dyeing fabrics, dressing leather.

Probably, from these ancient crafts, known in Egypt and Babylon, arose the "secret" hermetic art of the Middle Ages - alchemy, the most common in Europe in the 9th-16th centuries.

Originating in Egypt in the III-IV centuries, this area of practical chemistry was associated with magic and astrology. Its purpose was to develop ways and means of transforming less noble substances into more noble ones in order to achieve real perfection, both material and spiritual. During the search universal By means of such transformations, Arab and European alchemists obtained many new and valuable products, and also improved laboratory techniques.

1. The period of the birth of scientific chemistry(XVII - the end of the XVIII century; Paracelsus, Boyle, Cavendish, Stahl, Lavoisier, Lomonosov). It is characterized by the fact that chemistry stands out from natural science as an independent science. Its goals are determined by the development of industry in modern times. However, the theories of this period, as a rule, use either ancient or alchemical ideas about chemical phenomena. The period ended with the discovery of the law of conservation of mass in chemical reactions.

For example, iatrochemistry Paracelsus (XVI century) was devoted to the preparation of medicines and the treatment of diseases. Paracelsus explained the causes of diseases by a violation of chemical processes in the body. Like the alchemists, he reduced the variety of substances to a few elements - carriers of the basic properties of matter. Therefore, restoring their normal ratio by taking drugs cures the disease.

Theory phlogiston Stahl (XVII-XVIII centuries) summarized many chemical oxidation reactions associated with combustion. Stahl suggested the existence in all substances of the element "phlogiston" - the beginning of combustibility.

Then the combustion reaction looks like this: combustible body → residue + phlogiston; The reverse process is also possible: if the residue is saturated with phlogiston, i.e. mixed, for example, with coal, then again you can get the metal.

2. The period of discovery of the basic laws of chemistry(1800-1860; Dalton, Avogadro, Berzelius). The result of the period was the atomic-molecular theory:

a) all substances are composed of molecules that are in continuous chaotic motion;

b) all molecules are made up of atoms;

3. Modern period(started in 1860; Butlerov, Mendeleev, Arrhenius, Kekule, Semenov). It is characterized by the separation of sections of chemistry as independent sciences, as well as the development of related disciplines, for example, biochemistry. During this period, the periodic system of elements, theories of valence, aromatic compounds, electrochemical dissociation, stereochemistry, and the electronic theory of matter were proposed.

The modern chemical picture of the world looks like this:

1. Substances in the gaseous state are composed of molecules. In the solid and liquid state, only substances with a molecular crystal lattice (CO 2, H 2 O) consist of molecules. Most solids have either an atomic or an ionic structure and exist as macroscopic bodies (NaCl, CaO, S).

2. Chemical element - a certain type of atoms with the same nuclear charge. The chemical properties of an element are determined by the structure of its atom.

3. Simple substances are formed from atoms of one element (N 2, Fe). Complex substances or chemical compounds are formed by atoms of different elements (CuO, H 2 O).

4. Chemical phenomena or reactions are processes in which some substances are transformed into others in structure and properties without changing the composition of the nuclei of atoms.

5. The mass of substances entering into a reaction is equal to the mass of substances formed as a result of the reaction (law of conservation of mass).

6. Any pure substance, regardless of the method of preparation, always has a constant qualitative and quantitative composition (the law of composition constancy).

The main task chemistry- obtaining substances with predetermined properties and identifying ways to control the properties of a substance.

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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, in the later stages of the development of science (in the case of chemistry, already from the beginning of the 19th century), 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. The chemical revolution that completed this period 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 by the rapid development of science: the periodic system of elements, the theory of valence and the chemical structure of molecules, stereochemistry, chemical thermodynamics and chemical kinetics were created; 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 individual branches, acquiring the features of independent sciences.

In 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, the periodic law is created, two new conceptual systems of chemistry arise - 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 of 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 through 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 solutions, 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 is the molecule of a chemical substance 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 a 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 the co-reagents, the relative amounts of reagents, the 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 entire 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 represents a fundamentally new way of solving 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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abstract, added 05/20/2014

Laws of atomic-molecular theory. Stoichiometric ratios, gas mixtures. Solving standard and complex multi-variant tasks; derivation of formulas of chemical compounds. Calculation of a natural mineral, substances in a liquid, in a solid mixture; concentration.

The period of alchemy - from antiquity to the XVI century. Hermes Trismegistus Ancient Egypt is considered to be the birthplace of alchemy. Alchemists started their science from Hermes Trismegistus (aka the Egyptian god Thoth), and therefore the art of making gold was called hermetic. The alchemists sealed their vessels with a seal with the image of Hermes - hence the expression "hermetically sealed." There was a legend that the angels taught the art of turning "simple" metals into gold to earthly women with whom they married, as described in the Book of Genesis and the Book of the Prophet Enoch in the Bible. This art was expounded in a book called Hema.

At all times, alchemists passionately tried to solve two problems: transmutation and discovery of the elixir of immortality and eternal life. When solving the first problem, chemical science arose. When solving the second, scientific medicine and pharmacology arose. Transmutation is the process of turning base metals - mercury, zinc, lead into noble ones - gold and silver with the help of a philosopher's stone, which alchemists tried unsuccessfully to discover. "Squaring the circle": alchemical symbol of the philosopher's stone, 17th century.

Alchemy reached its highest development in three main types: Greco-Egyptian; · Arabic; After the Arab conquest of Egypt in the 7th c. n. e. alchemy began to develop in the Arab countries. Western European. The emergence of alchemy in Western Europe became possible thanks to the Crusades. Then the Europeans borrowed scientific and practical knowledge from the Arabs, among which was alchemy. European alchemy came under the protection of astrology and therefore acquired the character of a secret science. Europeans were the first to describe sulfuric acid, the process of formation of nitric acid, aqua regia. The undoubted merit of European alchemy was the study and production of mineral acids, salts, alcohol, phosphorus, etc. Alchemists created chemical equipment, developed various chemical operations: heating over direct fire, water bath, calcination, distillation, sublimation, evaporation, filtering, crystallization, etc.

The period of the birth of scientific chemistry - XVI-XVII centuries The conditions for the formation of chemistry as a science were: · renewal of European culture; the need for new types of industrial production; the discovery of the New World; expansion of trade relations. Theophrastus Bombast von Hohenheim In the 16th century. alchemy was replaced by a new direction, which was engaged in the preparation of medicines. This direction is called iatrochemistry. Iatrochemistry sought to combine medicine with chemistry, using a new type of preparation made from minerals. Iatrochemistry has brought significant benefits to chemistry, since it helped to free it from the influence of alchemy and laid the scientific and practical foundations of pharmacology.

In the 17th century, in the age of the rapid development of mechanics, in connection with the invention of the steam engine, chemistry became interested in the combustion process. The result of these studies was the theory of phlogiston, the founder of which was the German chemist and physician Georg Stahl. The phlogiston theory is based on the assertion that all combustible substances are rich in a special combustible substance - phlogiston. The more phlogiston a substance contains, the more it is capable of burning. Metals also contain phlogiston, but losing it, they turn into scale. When the scale is heated with coal, the metal takes phlogiston from it and is reborn. The phlogiston theory, despite its fallacy, provided an acceptable explanation for the process of smelting metals from ores. The question remained inexplicable why the ash and soot remaining from the combustion of substances such as wood, paper, fat, is much lighter than the original substance. Georg Stahl

Antoine Laurent Lavoisier 18th century French physicist Antoine Laurent Lavoisier, heating various substances in closed vessels, found that the total mass of all substances involved in the reaction remains unchanged. Lavoisier came to the conclusion that the mass of substances is never created or destroyed, but only passes from one substance to another. This conclusion, known today as the law of conservation of mass, became the basis for the entire development of chemistry in the 19th century.

The period of discovery of the basic laws of chemistry - the first 60 years of the XIX century. (gg.; Dalton, Avogadro, Berzelius). The result of the period was the atomic-molecular theory: a) all substances consist of molecules that are in continuous chaotic motion; b) all molecules are made up of atoms; c) atoms are the smallest, further indivisible components of molecules.

The modern period (began in 1860; Butlerov, Mendeleev, Arrhenius, Kekule, Semenov). It is characterized by the separation of sections of chemistry as independent sciences, as well as the development of related disciplines, for example, biochemistry. During this period, the periodic system of elements, theories of valence, aromatic compounds, electrochemical dissociation, stereochemistry, and the electronic theory of matter were proposed. Alexander Butlerov Svante August Arrhenius Nikolai Ivanovich Semenov

The modern chemical picture of the world looks like this: 1. Substances in the gaseous state consist of molecules. In the solid and liquid state, only substances with a molecular crystal lattice (CO2, H2O) consist of molecules. Most solids have either an atomic or an ionic structure and exist as macroscopic bodies (NaCl, CaO, S). 2. Chemical element - a certain type of atoms with the same nuclear charge. The chemical properties of an element are determined by the structure of its atom. 3. Simple substances are formed from atoms of one element (N2, Fe). Complex substances or chemical compounds are formed by atoms of different elements (CuO, H2O). 4. Chemical phenomena or reactions are processes in which some substances are transformed into others in structure and properties without changing the composition of the nuclei of atoms. 5. The mass of substances entering into a reaction is equal to the mass of substances formed as a result of the reaction (law of conservation of mass). 6. Any pure substance, regardless of the method of preparation, always has a constant qualitative and quantitative composition (the law of composition constancy). The main task of chemistry is to obtain substances with predetermined properties and to identify ways to control the properties of a substance.

The main problems of chemistry When solving the issue and the composition of a substance, chemists face 3 main problems: 1) The problem of a chemical element. From the point of view of modern chemistry, a chemical element is a collection of all atoms with the same nuclear charge. The physical meaning of the periodic law: The periodicity of the arrangement of elements in this table depended on the charge of the atomic nucleus. 2) The problem of a chemical compound. The essence of the problem lies in understanding the difference between what should be attributed to a chemical compound and what should be attributed to mixtures. Clarity was brought to this question when the "law of constancy of composition" was discovered. Discovered by Joseph Maus. 3) The problem of creating new materials.