The place of chemistry in the modern scientific picture of the world. Evolution of the chemical picture of the world. The main stages in the development of chemistry

home » Biology The place of chemistry in the modern scientific picture of the world. Evolution of the chemical picture of the world. The main stages in the development of chemistry

Chemistry is usually divided into 5 sections: inorganic, organic, physical, analytical and macromolecular chemistry.

The most important features of modern chemistry include:

1. Differentiation of the main sections of chemistry into separate, largely independent scientific disciplines, which is based on the difference between objects and research methods.

2. Integration of chemistry with other sciences. As a result of this process, arose: biochemistry, bioorganic chemistry and molecular biology, which study the chemical processes in living organisms. Both geochemistry and cosmochemistry arose at the intersection of disciplines.

3. The emergence of new physicochemical and physical research methods.

4. Formation of the theoretical foundation of chemistry based on the quantum wave concept.

With the development of chemistry to its modern level, four sets of approaches to solving the main problem have developed in it (the study of the origin of the properties of substances and the development on this basis of methods for obtaining substances with predetermined properties).

1. The doctrine of the composition, in which the properties of substances were associated exclusively with their composition. At this level, the content of chemistry was limited to its traditional definition - as the science of chemical elements and their compounds.

2. Structural chemistry. This concept combines theoretical concepts in chemistry that establish a connection between the properties of substances not only with the composition, but also with the structure of molecules. Within the framework of this approach, the concept of "reactivity" arose, including the idea of the chemical activity of individual fragments of a molecule - its individual atoms or entire atomic groups. The structural concept made it possible to transform chemistry from a predominantly analytical to a synthetic science. This approach eventually made it possible to create industrial technologies for the synthesis of many organic substances.

3. The doctrine of chemical processes. Within the framework of this concept, using the methods of physical kinetics and thermodynamics, factors affecting the direction and speed of chemical transformations and their results were identified. Chemistry revealed the mechanisms of reaction control and proposed ways to change the properties of the resulting substances.

4. Evolutionary chemistry. The last stage of the conceptual development of chemistry is associated with the use in it of some principles implemented in the chemistry of living nature. Within the framework of evolutionary chemistry, a search is carried out for such conditions under which self-improvement of reaction catalysts occurs in the process of chemical transformations. Essentially, it is about self-organization. chemical processes occurring in the cells of living organisms.

The birth of chemistry, as well as of all European science, despite their long history of formation, is associated with the emergence of the idea of the existence of laws of nature in modern times. The classical definition of chemistry is the definition according to which chemistry is the science of substances, their structure, properties, reactions and the laws that govern their transformations; one of the branches of natural science 1 . However, already in 1967, in the fundamental monograph “The Evolution of Ideas about the Basic Laws of Chemistry”, V. I. Kuznetsov concluded that the definition of chemistry as “the science of substances and their transformations” is outdated. The understanding of the structure of matter and the dynamics of chemical processes and, accordingly, the methodology of their study have changed. This led to the fruitful development of all the main areas of chemical research. New chemical compounds have been discovered. Thus, modern chemistry has more than 15 million chemical compounds and chemical reactions that exhibit unexpected properties and require the introduction of completely new concepts.

Yu. A. Zhdanov, referring to the problem of the specifics of the chemical form of motion, notes that, paradoxically, chemistry in the system of modern natural science occupies a somewhat ambiguous position: it is readily recognized as necessary scientific basis to understand biological, geological phenomena, to create technological processes, but often she is denied the status of a theoretical science, reducing it to quantum mechanics, static physics, thermodynamics. Zhdanov writes that there are many authoritative witnesses both from among philosophers and from among natural scientists who are ready to swear that chemistry as a science does not exist in principle, that the term “chemistry” hides a mixture of accurate, elegant physical theory and dirty, vulgar cuisine, which only out of compassion can be called a science. In such a situation, the question is valid, which raises in his research not only K). A. Zhdanov, but also many scientists and philosophers: if the theoretical side of chemistry is exhausted by physics, then only practical experimentation remains of chemistry, but who would dare to consider a field of activity devoid of its own theory as a science?

Although there are estimates state of the art of chemistry as the birth of a new chemistry, one of the problems that needs clarification is the question of the reduction of chemical knowledge to physical knowledge. This problem is a philosophical question, because, in essence, it is a question of how it is formulated.

V. Dekelman about whether chemistry has some own concept of being, or whether it is, by its very foundations, just a private area of physics. The tradition of reducing chemical changes to physical ones has its origins in the idea that the atoms of fire, air and earth mechanically interact with each other and form "mixed bodies" (R. Descartes, R. Boyle, I. Newton). According to M. Volkenstein, there is no theoretical chemistry, except for physics. This understanding was established with the development, firstly, of classical mechanics (M. Faraday) and was shared by many chemists; for example, D. I. Mendeleev admitted that the brilliance of chemical discoveries made modern chemistry a completely special science, while noting that “the time must undoubtedly come when chemical affinity will be considered as a mechanical phenomenon” . Secondly, with the development of quantum mechanics, the principles and provisions of which are applicable to solving traditional problems of chemical science, which gives grounds for belief in the quantum mechanical nature of the fundamental foundations of chemistry.

The physical basis of chemical knowledge is the following main postulates of quantum mechanics: 1) the concept of the wave function of an electron as a charge and spin (angular momentum) distributed in space and time; 2) the Pauli principle, which "organizes" electrons according to energy levels, spin states and their own orbitals (wave functions); 3) the E. Schrödinger equation as a quantum heir to the equations of classical mechanics.

In this regard, many physicists of the 20th century, for example, W. Heisenberg, P. Jordan, R. Feynman, developed the thesis about the possibility of reducing the laws of any chemical processes to fundamental physical laws. Moreover, physicists express their confidence that the moment will certainly come "when biology also completely merges with physics and chemistry, just as the current quantum mechanics has merged physics and chemistry together." Many representatives of Russian physics and philosophy also share this point of view. So, S. V. Vonsovsky writes that in all chemical processes we meet, first of all, with the atomism of the bodies of nature. Chemistry is understood by him as one of the most important natural science disciplines, primarily the science of the structure of molecules, as well as the processes of interaction of molecules and the behavior of substances during various chemical reactions.

The problem of reduction in the chemical picture of the world is an attempt to turn chemistry into the same exact science as theoretical physics. However, there is another basis of chemistry - mathematical, the expression of which was the establishment of many quantitative laws, exact laws (including the electronic periodicity of Mendeleev's law), the highest measuring level for determining atomic-molecular, thermodynamic and kinetic constants characterizing matter and chemical process. Along with the fundamental physical and mathematical basis of chemistry, a large number of research areas of chemical knowledge itself have been formed today. Moreover, the trends in the development of interdisciplinary interactions both at the junctions of chemical disciplines and between all natural sciences have led to the action of feedbacks between disciplines.

The main thesis of the tradition that opposes the reduction of chemistry to physics: “In a chemical phenomenon there is always something more than just a physical phenomenon” (W. Ostwald, N. N. Semenov, Yu. A. Zhdanov, B. M. Kedrov, A. N. Nesmeyanov and others). This provision leads to the need to formulate the problem of the object basis of chemistry. The expression of this problem can be the question: do chemistry and physics deal with the same object of study?

As G. A. Krestov notes, chemistry studies the world by the united concept of matter, which exists in the form of matter and field, possessing mass, energy and characterized by the dialectical unity of corpuscular and wave properties.

However, physics operates with the concept of "field". V. M. Kedrov notes that atoms and molecules can be the final stage in the development of an object in relation to their original structural elements and be the object of study of physics, but they can also be the initial chemical unit in relation to the molecular structures arising from it, and in this case act as an object of study of chemistry 11 .

Proponents of reducing chemical bonds to physical ones postulate an understanding of chemical interaction as a special kind of more general electromagnetic interaction. If we take into account that an individual atom is not yet a chemical substance, then the periodic system of elements of D. I. Mendeleev is not a chemical concept. As V. A. Engelgardt rightly points out when analyzing a chemical process: “... a part that was previously independent ceases to exist as such, becomes a component of an internally united integral whole. Something new arises, something that did not exist before, with new qualities inherent in it.

The peculiarity of the chemical picture of the world is that the main objects of study are not just atoms or molecules, but a very complex organization of matter. It must be taken into account that the rearrangement of the electronic orbitals of the atom occurs inside the atom as a whole. That is, the rearrangement of electronic orbitals is due to the entire structure of the atom, and not only to the individual properties of electrons. Only within the framework of the whole can we say that this or that interaction is chemical. It must be taken into account that chemical compounds are not built from individual atoms, but from atomic nuclei (atomic cores) connected by a socialized electron continuum. This causes the fact that the process of losing an electron by one atom and gaining it by another cannot reflect the essence of chemical interaction.

In this matter, such researchers as N. M. Cheremnykh and O. S. Sirotkin rightly believe that it is the presence of a chemical bond in a substance that is the criterion that it is an object of chemical research; neither elementary particle, neither the atom (sometimes considered a “legitimate” object of chemistry) satisfies this criterion, and therefore the models of the elementary and atomic levels of the organization of matter cannot be extrapolated to chemical level. A chemical system is a kind of integrity, therefore, a description of the individual elements on the basis of which it arose cannot give a complete picture of the chemical process, for example, the formation of glycogen from glucose, etc. It is fair to say that there is a difference between physics and chemistry, it is not reduced only to the difference between chemical and physical (electromagnetic) interactions. N. N. Semyonov identifies the basic principles from which all chemical laws that cannot be reduced to the laws of physics can be derived:

Principle electronic structure molecular systems; the doctrine of the relationship between the structure and properties of molecular

- the doctrine of the reactivity of chemical compounds;
- the concept of the unity of chemical phenomena.

Moreover, if we take into account the fact that, according to the authoritative opinion of the physicochemist N. N. Semenov, the essence of the chemical is the chemical process, considered in modern chemistry as a kinetic continuum of many substances, then it is the chemical process that forms the bridge between the objects of physics and the objects of biology.

See: Chemical Encyclopedic Dictionary. M.: Soviet Encyclopedia, 1983.
See: Kuznetsov V.I. Evolution of ideas about the basic laws of chemistry.M. : Nauka, 1967.
See: Zhdanov Yu. A. Carbon and life. Rostov n / a: Publishing House of the Russian State University, 1968; Zhdanov Yu. A. Essays on the methodology of organic chemistry. M. : Vyssh. school, 1960.
See: Kuznetsov V. I. Dialectics of development of chemistry. Moscow: Nauka, 1973; Solovyov Yu. I., Trifonov D. II., Shamin A. II. Development of the main directions of modern chemistry. Moscow: Education, 1978; Polit L. General chemistry. M. : Mir, 1974.

(structural levels of matter organization from the point of view of chemistry).

Chemistry is one of the branches of natural science, the subject of which is the chemical elements (atoms), the simple and complex substances (molecules) they form, their transformations and the laws that these transformations obey. By definition, D.I. Mendeleev (1871), "chemistry in its present state can be called the doctrine of the elements." The origin of the word "chemistry" is not completely clear. Many researchers believe that it comes from the ancient name of Egypt - Chemia (Greek Chemía, found in Plutarch), which is derived from "hem" or "hame" - black and means "science of the black earth" (Egypt), "Egyptian science" .

Modern chemistry is closely connected both with other sciences and with all branches. National economy. The qualitative feature of the chemical form of the motion of matter and its transitions to other forms of motion determines the versatility of chemical science and its connections with areas of knowledge that study both lower and higher forms of motion. Knowledge of the chemical form of the motion of matter enriches common doctrine about the development of nature, the evolution of matter in the universe, contributes to the formation of a holistic materialistic picture of the world. The contact of chemistry with other sciences gives rise to specific areas of their mutual penetration. Thus, the areas of transition between chemistry and physics are represented by physical chemistry and chemical physics. Between chemistry and biology, chemistry and geology, special border areas arose - geochemistry, biochemistry, biogeochemistry, molecular biology. The most important laws of chemistry are formulated in mathematical language, and theoretical chemistry also cannot develop without mathematics. Chemistry has exerted and is exerting an influence on the development of philosophy, and has itself experienced and is experiencing its influence. Historically, two main branches of chemistry have developed: inorganic chemistry, which studies primarily chemical elements and the simple and complex substances they form (except carbon compounds), and organic chemistry, the subject of which is carbon compounds with other elements (organic substances). Until the end of the 18th century. the terms "inorganic chemistry" and "organic chemistry" only indicated from which "kingdom" of nature (mineral, plant or animal) certain compounds were obtained. Starting from the 19th century. these terms have come to indicate the presence or absence of carbon in a given substance. Then they acquired a new, broader meaning. Inorganic chemistry comes into contact primarily with geochemistry and then with mineralogy and geology, i.e. with the sciences of inorganic nature. Organic chemistry is a branch of chemistry that studies a variety of carbon compounds up to the most complex biopolymer substances; through organic and bioorganic chemistry Chemistry borders on biochemistry and further on biology, i.e. with the totality of the sciences of living nature. At the junction between inorganic and organic chemistry is the area of organoelement compounds. In chemistry, ideas about the structural levels of the organization of matter gradually formed. The complication of a substance, starting from the lowest, atomic, goes through the steps of molecular, macromolecular, or high-molecular compounds (polymer), then intermolecular (complex, clathrate, catenane), and finally, diverse macrostructures (crystal, micelle) up to indefinite non-stoichiometric formations. The corresponding disciplines gradually developed and became isolated: the chemistry of complex compounds, polymers, crystal chemistry, the study of dispersed systems and surface phenomena, alloys, etc.

The study of chemical objects and phenomena by physical methods, the establishment of patterns of chemical transformations, based on general principles physics, underlies physical chemistry. This area of chemistry includes a number of largely independent disciplines: chemical thermodynamics, chemical kinetics, electrochemistry, colloid chemistry, quantum chemistry and the study of the structure and properties of molecules, ions, radicals, radiation chemistry, photochemistry, the doctrine of catalysis, chemical equilibrium, solutions and others. analytical chemistry, whose methods are widely used in all areas of chemistry and the chemical industry. In the areas of practical application of chemistry, such sciences and scientific disciplines as chemical technology with its many branches, metallurgy, agricultural chemistry, medical chemistry, forensic chemistry, etc., arose.

The external world, which exists independently of a person and his consciousness, represents various types of motion of matter. Matter exists in perpetual motion, the measure of which is energy. The most studied are such forms of the existence of matter as matter and field. To a lesser extent, science has penetrated into the essence of vacuum and information as possible forms of existence of material objects.

A substance is understood as a stable collection of particles (atoms, molecules, etc.) that have a rest mass. The field is considered as a material environment that ensures the interaction of particles. modern science considers that the field is a stream of quanta that do not have a rest mass.

The material bodies surrounding a person consist of various substances. At the same time, objects of the real world, which have a rest mass and occupy a certain amount of space, are called bodies.

Each body has its own physical parameters and properties. And the substances of which they are composed have chemical and physical properties. As physical properties, one can name the aggregate states of a substance, density, solubility, temperature, color, taste, smell, etc.

There are solid, liquid, gaseous and plasma aggregate states of matter. Under normal conditions (temperature 20 degrees Celsius, pressure 1 atmosphere), various substances are in different states of aggregation. For example: sucrose, sodium chloride (salt), sulfur are solids; water, benzene, sulfuric acid - liquids; oxygen, carbon dioxide, methane are gases.

The main task of chemistry as a science is to identify and describe such properties of a substance that allow one substance to be converted into another based on chemical reactions.

Chemical transformations are a special form of matter movement, which is due to the interaction of atoms, leading to the formation of molecules, associates and aggregates.

From the point of view of chemical organization, the atom is the initial level in the general structure of matter.

Chemistry, therefore, studies a special "chemical" form of the motion of matter, a characteristic feature of which is the qualitative transformation of matter.

Chemistry is a science that studies the transformation of one substance into another, accompanied by a change in their composition and structure, and also explores the mutual transitions between these processes.

The term "natural science" means knowledge about nature or natural science. The beginning of the study of nature was laid by natural philosophy (“natural history” translated from German “naturphilosophie”; and translated from Latin - “natura” - nature, “Sophia” - wisdom).

In the course of the development of each science, including chemistry, the mathematical apparatus, the conceptual apparatus of theories developed, the experimental base and experimental technique improved. As a result, there was a complete differentiation in the subjects of study of various natural sciences. Chemistry mainly studies the atomic and molecular level organization of matter, as shown in Fig. 8.1.

Rice. 8.1. Levels of matter studied by chemical science

Basic concepts and laws of chemistry

At the heart of modern natural science is the principle of conservation of matter, motion and energy. Formulated by M.V. Lomonosov in 1748. This principle has become firmly established in chemical science. In 1756 M.V. Lomonosov, studying chemical processes, discovered the constancy of the total mass of substances involved in a chemical reaction. This discovery became the most important law of chemistry - the law of conservation and the relationship of mass and energy. In the modern interpretation, it is formulated as follows: the mass of substances that entered into a chemical reaction is equal to the mass of substances formed as a result of the reaction.

In 1774, the famous French chemist A. Lavoisier supplemented the law of conservation of mass with ideas about the invariance of the masses of each of the substances participating in the reaction.

In 1760 M.V. Lomonosov formulated the law of conservation of energy: energy does not arise from nothing and does not disappear without a trace, it turns from one form into another. The German scientist R. Mayer in 1842 experimentally confirmed this law. And the English scientist Joule established the equivalence of various types of energy and work (1 cal = 4.2 J). For chemical reactions, this law is formulated as follows: the energy of the system, including the substances that entered into the reaction, is equal to the energy of the system, including the substances formed as a result of the reaction.

The law of composition constancy was discovered by the French scientist J. Proust (1801): any chemically pure individual substance always has the same quantitative composition, regardless of the method of its preparation. In other words, no matter how water is obtained, when hydrogen is burned or when calcium hydroxide (Ca (OH) 2) is decomposed, the ratio of the masses of hydrogen and oxygen in it is 1:8.

In 1803 J. Dalton (an English physicist and chemist) discovered the law of multiple ratios, according to which, if two elements form several compounds among themselves, then the masses of one of the elements per the same mass of the other are related to each other as small integers. This law is a confirmation of atomistic ideas about the structure of matter. If the elements are combined in multiple ratios, then the chemical compounds differ by whole atoms, which represent the smallest amount of the element that entered into the compound.

The most important discovery of chemistry in the 19th century is Avogadro's law. As a result of quantitative studies of reactions between gases, the French physicist J.L. Gay-Lussac found that the volumes of the reacting gases are related to each other and to the volumes of the resulting gaseous products as small integers. The explanation for this fact is given by Avogadro's law (discovered by the Italian chemist A. Avogadro in 1811): equal volumes of any gases taken at the same temperature and pressure contain the same number of molecules.

The law of equivalents is often used in chemical calculations. It follows from the law of composition constancy that the interaction of elements with each other takes place in strictly defined (equivalent) ratios. Therefore, the term equivalent was established in chemical science as the main one. The equivalent of an element is that amount of it that combines with one mole of hydrogen or replaces the same number of hydrogen atoms in chemical reactions. The mass of one equivalent of a chemical element is called its equivalent mass. The concepts of equivalents and equivalent masses apply to complex substances as well. The equivalent of a complex substance is such an amount of it that interacts without residue with one equivalent of hydrogen or with one equivalent of any other substance. The formulation of the law of equivalents was given by Richter at the end of the 18th century: all substances react with each other in quantities proportional to their equivalents. Another formulation of this law says: the masses (volumes) of substances reacting with each other are proportional to their equivalent masses (volumes). The mathematical record of this law is: m 1: m 2 \u003d E 1: E 2, where m 1 and m 2 are the masses of interacting substances, E 1 and E 2 are the equivalent masses of these substances, expressed in kg / mol.

An important role is played by the periodic law of D.I. Mendeleev, whose modern interpretation says that the arrangement order and chemical properties of elements are determined by the charge of the nucleus.

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 was in Ancient Greece to the region 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 3rd-4th centuries, this direction 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. Chemical properties element is 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.

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

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.

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;

The modern chemical picture of the world looks like this:

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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