Classification of chemical reactions in inorganic chemistry - document. Fundamentals of Inorganic Chemistry

The chemistry course in schools begins in the 8th grade with the study general principles science: possible types of bonds between atoms, types of crystal lattices and the most common reaction mechanisms are described. This becomes the foundation for the study of an important, but more specific section - inorganics.

What it is

This is a science that examines the structural principles, basic properties and reactivity of all elements of the periodic table. An important role in inorganics is played by the Periodic Law, which orders systematic classification substances by changes in their mass, number and type.

The course also covers compounds formed by the interaction of elements of the table (the only exception is the area of ​​hydrocarbons, discussed in the chapters of organics). Problems in inorganic chemistry allow you to work out the received theoretical knowledge on practice.

Science in historical perspective

The name "inorganics" appeared in accordance with the idea that it covers a part of chemical knowledge that is not related to the activities of biological organisms.

Over time it has been proven that most organic world can produce “non-living” compounds, and hydrocarbons of any type are synthesized in the laboratory. Thus, from ammonium cyanate, which is a salt in the chemistry of elements, the German scientist Wöhler was able to synthesize urea.

To avoid confusion with the nomenclature and classification of types of research in both sciences, the curriculum of school and university courses, following general chemistry, involves the study of inorganics as a fundamental discipline. In the scientific world, a similar sequence remains.

Classes of inorganic substances

Chemistry provides such a presentation of material in which the introductory chapters of inorganics consider the Periodic Law of the Elements. a special type, which is based on the assumption that the atomic charges of nuclei affect the properties of substances, and these parameters change cyclically. Initially, the table was constructed as a reflection of the increase in the atomic masses of elements, but soon this sequence was rejected due to its inconsistency in the aspect in which inorganic substances require consideration of this issue.

Chemistry, in addition to the periodic table, assumes the presence of about a hundred figures, clusters and diagrams reflecting the periodicity of properties.

Currently, a consolidated version of considering such a concept as classes of inorganic chemistry is popular. The columns of the table indicate elements depending on their physical and chemical properties, and the rows indicate periods that are similar to each other.

Simple substances in inorganics

A sign in the periodic table and a simple substance in a free state are most often different things. In the first case, only the specific type of atoms is reflected, in the second - the type of particle connection and their mutual influence in stable forms.

Chemical bonds in simple substances determine their division into families. Thus, two broad types of groups of atoms can be distinguished - metals and non-metals. The first family contains 96 elements out of 118 studied.

Metals

The metal type assumes the presence of a bond of the same name between particles. The interaction is based on the sharing of lattice electrons, which is characterized by non-directionality and unsaturation. That is why metals conduct heat and charges well, have a metallic luster, malleability and ductility.

Conventionally, metals are on the left in the periodic table when drawing a straight line from boron to astatine. Elements close in location to this feature are most often of a borderline nature and exhibit dual properties (for example, germanium).

Metals mostly form basic compounds. The oxidation states of such substances usually do not exceed two. Metallicity increases within a group and decreases within a period. For example, radioactive francium exhibits more basic properties than sodium, and in the halogen family, iodine even exhibits a metallic luster.

The situation is different in a period - sublevels are completed in front of which there are substances with opposite properties. In the horizontal space of the periodic table, the manifested reactivity of elements changes from basic through amphoteric to acidic. Metals are good reducing agents (they accept electrons when forming bonds).

Nonmetals

This type of atom is included in the main classes of inorganic chemistry. Nonmetals occupy right side periodic table, exhibiting typically acidic properties. Most often, these elements are found in the form of compounds with each other (for example, borates, sulfates, water). In the free molecular state, the existence of sulfur, oxygen and nitrogen is known. There are also several diatomic non-metal gases - in addition to the two mentioned above, these include hydrogen, fluorine, bromine, chlorine and iodine.

They are the most common substances on earth - silicon, hydrogen, oxygen and carbon are especially common. Iodine, selenium and arsenic are very rare (this also includes radioactive and unstable configurations, which are located in the last periods of the table).

In compounds, nonmetals behave primarily as acids. They are powerful oxidizing agents due to the possibility of joining additional number electrons to complete the level.

in inorganics

In addition to substances that are represented by one group of atoms, there are compounds that include several different configurations. Such substances can be binary (consisting of two different particles), three-, four-element, and so on.

Two-element substances

Chemistry attaches particular importance to the binary nature of bonds in molecules. Classes of inorganic compounds are also considered from the point of view of the bonds formed between atoms. It can be ionic, metallic, covalent (polar or nonpolar) or mixed. Typically, such substances clearly exhibit basic (in the presence of metal), amphoteric (dual - especially characteristic of aluminum) or acidic (if there is an element with an oxidation state of +4 and higher) qualities.

Three-element associates

Topics in inorganic chemistry include consideration of this type of combination of atoms. Compounds consisting of more than two groups of atoms (inorganics most often deal with three-element species) are usually formed with the participation of components that differ significantly from each other in physicochemical parameters.

Possible types of bonds are covalent, ionic and mixed. Typically, three-element substances are similar in behavior to binary substances due to the fact that one of the forces of interatomic interaction is much stronger than the other: the weak one is formed secondarily and has the ability to dissociate in solution faster.

Inorganic Chemistry Classes

The vast majority of substances studied in the inorganics course can be considered according to a simple classification depending on their composition and properties. Thus, a distinction is made between oxides and salts. It is better to start considering their relationship by becoming familiar with the concept of oxidized forms, in which almost any inorganic substance can appear. The chemistry of such associates is discussed in the chapters on oxides.

Oxides

An oxide is a compound of any chemical element with oxygen in an oxidation state of -2 (in peroxides -1, respectively). Bond formation occurs due to the donation and addition of electrons with the reduction of O 2 (when the most electronegative element is oxygen).

They can exhibit acidic, amphoteric, and basic properties depending on the second group of atoms. If in an oxide it does not exceed the oxidation state +2, if a non-metal - from +4 and above. In samples with a dual nature of parameters, a value of +3 is achieved.

Acids in inorganics

Acidic compounds have an environmental reaction of less than 7 due to the content of hydrogen cations, which can go into solution and subsequently be replaced by a metal ion. According to the classification, they are complex substances. Most acids can be prepared by diluting the corresponding oxides with water, for example by forming sulfuric acid after hydration of SO 3 .

Basic inorganic chemistry

The properties of this type of compound are due to the presence of the hydroxyl radical OH, which gives the reaction of the medium above 7. Soluble bases are called alkalis; they are the strongest in this class of substances due to complete dissociation (decomposition into ions in the liquid). The OH group can be replaced by acidic residues when forming salts.

Inorganic chemistry is a dual science that can describe substances with different points vision. In the protolytic theory, bases are considered as hydrogen cation acceptors. This approach expands the concept of this class of substances, calling any substance capable of accepting a proton an alkali.

Salts

This type of compound is between bases and acids, as it is a product of their interaction. Thus, the cation is usually a metal ion (sometimes ammonium, phosphonium or hydronium), and the anionic substance is an acidic residue. When a salt is formed, hydrogen is replaced by another substance.

Depending on the ratio of the number of reagents and their strength relative to each other, it is rational to consider several types of interaction products:

• basic salts are obtained if the hydroxyl groups are not completely replaced (such substances have an alkaline reaction);
• acid salts are formed in the opposite case - when there is a lack of reacting base, hydrogen partially remains in the compound;
• the most famous and easiest to understand are the average (or normal) samples - they are the product of complete neutralization of the reactants with the formation of water and a substance with only a metal cation or its analogue and an acid residue.

Inorganic chemistry is a science that involves dividing each of the classes into fragments that are considered at different times: some earlier, others later. With a more in-depth study, 4 more types of salts are distinguished:

• Doubles contain a single anion in the presence of two cations. Typically, such substances are obtained by combining two salts with the same acid residue, but different metals.
• The mixed type is the opposite of the previous one: its basis is one cation with two different anions.
• Crystalline hydrates are salts whose formula contains water in a crystallized state.
• Complexes are substances in which the cation, anion, or both of them are presented in the form of clusters with a forming element. Such salts can be obtained mainly from elements of subgroup B.

Other substances included in the inorganic chemistry workshop that can be classified as salts or as separate chapters of knowledge include hydrides, nitrides, carbides and intermetallic compounds (compounds of several metals that are not an alloy).

Results

Inorganic chemistry is a science that is of interest to every specialist in this field, regardless of his interests. It includes the first chapters studied in school on this subject. The course in inorganic chemistry provides for the systematization of large amounts of information in accordance with a clear and simple classification.

Topics of the Unified State Examination codifier: Classification chemical reactions in organic and inorganic chemistry.

Chemical reactions - this is a type of particle interaction when one of the chemical substances others are obtained that differ from them in properties and structure. Substances that enter in reaction - reagents. Substances that are formed during a chemical reaction - products.

During a chemical reaction, chemical bonds are broken and new ones are formed.

During chemical reactions, the atoms involved in the reaction do not change. Only the order of connection of atoms in molecules changes. Thus, the number of atoms of the same substance does not change during a chemical reaction.

Chemical reactions are classified according to different criteria. Let's consider the main types of classification of chemical reactions.

Classification according to the number and composition of reacting substances

Based on the composition and number of reacting substances, reactions that occur without changing the composition of the substances are divided into reactions that occur with a change in the composition of the substances:

1. Reactions that occur without changing the composition of substances (A → B)

To such reactions in inorganic chemistry Allotropic transitions of simple substances from one modification to another can be attributed:

S orthorhombic → S monoclinic.

IN organic chemistry such reactions include isomerization reactions , when from one isomer under the influence of a catalyst and external factors a different one is obtained (usually a structural isomer).

For example, isomerization of butane to 2-methylpropane (isobutane):

CH 3 -CH 2 -CH 2 -CH 3 → CH 3 -CH(CH 3)-CH 3.

2. Reactions that occur with a change in composition

• Compound reactions (A + B + ... → D)- these are reactions in which one new complex substance is formed from two or more substances. IN inorganic chemistry Compound reactions include combustion reactions of simple substances, the interaction of basic oxides with acidic ones, etc. In organic chemistry such reactions are called reactions accessions Addition reactions — These are reactions in which another molecule is added to the organic molecule in question. Addition reactions include reactions hydrogenation(interaction with hydrogen), hydration(water connection), hydrohalogenation(addition of hydrogen halide), polymerization(attachment of molecules to each other to form a long chain), etc.

For example, hydration:

CH 2 =CH 2 + H 2 O → CH 3 -CH 2 -OH

• Decomposition reactions (A → B+C+…)- these are reactions during which several less complex or simple substances are formed from one complex molecule. In this case, both simple and complex substances can be formed.

For example, during decomposition hydrogen peroxide:

2H2O2→ 2H 2 O + O 2 .

In organic chemistry separate decomposition reactions and elimination reactions . Elimination reactions — These are reactions during which atoms or atomic groups are separated from the original molecule while maintaining its carbon skeleton.

For example, the reaction of hydrogen abstraction (dehydrogenation) from propane:

C 3 H 8 → C 3 H 6 + H 2

As a rule, the name of such reactions contains the prefix “de”. Decomposition reactions in organic chemistry usually involve the breaking of a carbon chain.

For example, reaction butane cracking(splitting into simpler molecules by heating or under the influence of a catalyst):

C 4 H 10 → C 2 H 4 + C 2 H 6

• Substitution reactions - these are reactions during which atoms or groups of atoms of one substance are replaced by atoms or groups of atoms of another substance. In inorganic chemistry These reactions occur according to the following scheme:

AB + C = AC + B.

For example, more active halogens displace less active ones from compounds. Interaction potassium iodide With chlorine:

2KI + Cl 2 → 2KCl + I 2.

Both individual atoms and molecules can be replaced.

For example, upon fusion less volatile oxides are crowding out more volatile from salts. Yes, non-volatile silicon oxide displaces carbon monoxide from sodium carbonate when fused:

Na 2 CO 3 + SiO 2 → Na 2 SiO 3 + CO 2

IN organic chemistry Substitution reactions are reactions in which part of an organic molecule replaced to other particles. In this case, the substituted particle, as a rule, combines with part of the substituent molecule.

For example, reaction methane chlorination:

CH 4 + Cl 2 → CH 3 Cl + HCl

In terms of the number of particles and the composition of interaction products, this reaction is more similar to an exchange reaction. Nevertheless, by mechanism such a reaction is a replacement reaction.

• Exchange reactions - these are reactions during which two complex substances exchange their constituent parts:

AB + CD = AC + BD

Exchange reactions include ion exchange reactions flowing in solutions; reactions illustrating the acid-base properties of substances and others.

Example exchange reactions in inorganic chemistry - neutralization hydrochloric acid alkali:

NaOH + HCl = NaCl + H2O

Example exchange reactions in organic chemistry - alkaline hydrolysis of chloroethane:

CH 3 -CH 2 -Cl + KOH = CH 3 -CH 2 -OH + KCl

Classification of chemical reactions according to changes in the oxidation state of elements forming substances

By changing the oxidation state of elements chemical reactions are divided into redox reactions, and the reactions going on without changing oxidation states chemical elements.

• Redox reactions (ORR) are reactions during which oxidation states substances change. In this case an exchange takes place electrons.

IN inorganic chemistry Such reactions usually include reactions of decomposition, substitution, combination, and all reactions involving simple substances. To equalize the ORR, the method is used electronic balance(the number of electrons given must be equal to the number received) or electron-ion balance method.

IN organic chemistry separate oxidation and reduction reactions, depending on what happens to the organic molecule.

Oxidation reactions in organic chemistry are reactions during which the number of hydrogen atoms decreases or the number of oxygen atoms in the original organic molecule increases.

For example, oxidation of ethanol under the action of copper oxide:

CH 3 -CH 2 -OH + CuO → CH 3 -CH=O + H 2 O + Cu

Recovery reactions in organic chemistry, these are reactions during which the number of hydrogen atoms increases or the number of oxygen atoms decreases in an organic molecule.

For example, recovery acetaldehyde hydrogen:

CH 3 -CH=O + H 2 → CH 3 -CH 2 -OH

• Protolytic and metabolic reactions - These are reactions during which the oxidation states of atoms do not change.

For example, neutralization caustic soda nitric acid:

NaOH + HNO 3 = H 2 O + NaNO 3

Classification of reactions by thermal effect

By thermal effect reactions are divided into exothermic And endothermic.

Exothermic reactions - these are reactions accompanied by the release of energy in the form of heat (+ Q). Such reactions include almost all compound reactions.

Exceptions- reaction nitrogen With oxygen with education nitric oxide (II) - endothermic:

N 2 + O 2 = 2NO – Q

Gaseous reaction hydrogen with hard iodine Also endothermic:

H 2 + I 2 = 2HI – Q

Exothermic reactions that produce light are called reactions combustion.

For example, methane combustion:

CH 4 + O 2 = CO 2 + H 2 O

Also exothermic are:

Endothermic reactions are reactions accompanied by energy absorption in the form of heat ( —Q ). As a rule, most reactions occur with the absorption of heat decomposition(reactions requiring prolonged heating).

For example, decomposition limestone:

CaCO 3 → CaO + CO 2 – Q

Also endothermic are:

• hydrolysis reactions;
• reactions that occur only when heated;
• reactions that occur onlyat very high temperatures ah or under the influence of an electrical discharge.

For example, conversion of oxygen to ozone:

3O 2 = 2O 3 - Q

IN organic chemistry With the absorption of heat, decomposition reactions occur. For example, cracking pentane:

C 5 H 12 → C 3 H 6 + C 2 H 6 – Q.

Classification of chemical reactions according to the state of aggregation of the reacting substances (according to phase composition)

Substances can exist in three main forms states of aggregation — hard, liquid And gaseous. By phase state share reactions homogeneous And heterogeneous.

• Homogeneous reactions - these are reactions in which the reactants and products are in one phase, and the collision of reacting particles occurs throughout the entire volume of the reaction mixture. Homogeneous reactions include interactions liquid-liquid And gas-gas.

For example, oxidation sulfur dioxide:

2SO 2 (g) + O 2 (g) = 2SO 3 (g)

• Heterogeneous reactions - these are reactions in which the reactants and products are in different phases. In this case, the collision of reacting particles occurs only at the phase contact boundary. Such reactions include interactions gas-liquid, gas-solid, solid-solid, and solid-liquid.

For example, interaction carbon dioxide And calcium hydroxide:

CO 2 (g) + Ca (OH) 2 (solution) = CaCO 3 (tv) + H 2 O

To classify reactions by phase state, it is useful to be able to determine phase states of substances. This is quite easy to do using knowledge about the structure of matter, in particular about.

Substances with ionic, atomic or metal crystal lattice, usually hard under normal conditions; substances with molecular lattice, usually, liquids or gases under normal conditions.

Please note that when heated or cooled, substances can change from one phase state to another. In this case, it is necessary to focus on the conditions for a specific reaction and physical properties substances.

For example, receiving synthesis gas occurs at very high temperatures at which water - steam:

CH 4 (g) + H2O (g) = CO (g) + 3H 2 (g)

Thus, steam reform methane — homogeneous reaction.

Classification of chemical reactions according to the participation of a catalyst

A catalyst is a substance that speeds up a reaction, but is not part of the reaction products. The catalyst participates in the reaction, but is practically not consumed during the reaction. Conventionally, the catalyst action diagram TO when substances interact A+B can be depicted as follows: A + K = AK; AK + B = AB + K.

Depending on the presence of a catalyst, catalytic and non-catalytic reactions are distinguished.

• Catalytic reactions - these are reactions that occur with the participation of catalysts. For example, the decomposition of Berthollet salt: 2KClO 3 → 2KCl + 3O 2.
• Non-catalytic reactions - These are reactions that occur without the participation of a catalyst. For example, ethane combustion: 2C 2 H 6 + 5O 2 = 2CO 2 + 6H 2 O.

All reactions occurring in the cells of living organisms occur with the participation of special protein catalysts - enzymes. Such reactions are called enzymatic.

The mechanism of action and functions of catalysts are discussed in more detail in a separate article.

Classification of reactions by direction

Reversible reactions - these are reactions that can occur in both the forward and reverse directions, i.e. when, under given conditions, reaction products can interact with each other. Reversible reactions include most homogeneous reactions, esterification; hydrolysis reactions; hydrogenation-dehydrogenation, hydration-dehydration; production of ammonia from simple substances, oxidation of sulfur dioxide, production of hydrogen halides (except hydrogen fluoride) and hydrogen sulfide; methanol synthesis; production and decomposition of carbonates and bicarbonates, etc.

Irreversible reactions - these are reactions that proceed predominantly in one direction, i.e. The reaction products cannot react with each other under these conditions. Examples of irreversible reactions: combustion; explosive reactions; reactions that occur with the formation of gas, precipitate or water in solutions; dissolution of alkali metals in water; and etc.

Inorganic chemistry- a branch of chemistry that is associated with the study of the structure, reactivity and properties of all chemical elements and their inorganic compounds. This branch of chemistry covers all compounds except organic matter(a class of compounds that includes carbon, with the exception of a few simplest compounds, usually classified as inorganic). Differences between organic and inorganic compounds, containing , are, according to some representations, arbitrary. Inorganic chemistry studies chemical elements and the simple and complex substances they form (except organic). The number of inorganic substances known today is approaching 500 thousand.

The theoretical basis of inorganic chemistry is periodic law and based on it periodic table of D. I. Mendeleev. The main task of inorganic chemistry is the development and scientific basis ways to create new materials with properties necessary for modern technology.

Classification of chemical elements

Periodic table of chemical elements ( Mendeleev table) - classification of chemical elements that establishes the relationship various properties chemical elements from the charge of the atomic nucleus. A system is a graphical expression of the periodic law, . Its original version was developed by D.I. Mendeleev in 1869-1871 and was called “Natural System of Elements,” which established the dependence of the properties of chemical elements on their atomic mass. In total, several hundred options for depicting the periodic table have been proposed, but in modern version The system involves the reduction of elements into a two-dimensional table, in which each column (group) defines the basic physical and chemical properties, and the rows represent periods that are somewhat similar to each other.

Simple substances

They consist of atoms of one chemical element (they are a form of its existence in a free state). Depending on the chemical bond between atoms, all simple substances in inorganic chemistry are divided into two main groups: and. The former are characterized by a metallic bond, the latter by a covalent bond. There are also two adjacent groups - metal-like and non-metal-like substances. There is such a phenomenon as allotropy, which consists in the possibility of the formation of several types of simple substances from atoms of the same element, but with different structures of the crystal lattice; each of these types is called an allotropic modification.

Metals

(from Latin metallum - mine, mine) - a group of elements with characteristic metallic properties, such as high thermal and electrical conductivity, positive temperature coefficient of resistance, high ductility and metallic luster. Of the 118 chemical elements discovered in this moment, metals include:

• 38 in the group of transition metals,
• 11 in the group of light metals,
• 7 in the group of semimetals,
• 14 in the group lanthanides + lanthanum,
• 14 in the group actinides + actinium,
• outside certain groups.

Thus, 96 of all discovered elements belong to metals.

Nonmetals

Chemical elements with typically nonmetallic properties, occupying the upper right corner of the Periodic Table of Elements. Occurs in molecular form as simple substances in nature.

Chemistry- the science of substances, the laws of their transformations (physical and chemical properties) and application.

Currently, more than 100 thousand inorganic and more than 4 million organic compounds are known.

Chemical phenomena: some substances are transformed into others that differ from the original ones in composition and properties, while the composition of the atomic nuclei does not change.

Physical phenomena: the physical state of substances changes (vaporization, melting, electrical conductivity, radiation of heat and light, malleability, etc.) or new substances are formed with a change in the composition of atomic nuclei.

Atomic-molecular science.

1. All substances are made up of molecules.

Molecule - the smallest particle of a substance that has its chemical properties.

2. Molecules are made up of atoms.

Atom - the smallest particle of a chemical element that retains all its chemical properties. Different elements have different atoms.

3. Molecules and atoms are in continuous motion; there are forces of attraction and repulsion between them.

Chemical element - this is a type of atoms characterized by certain nuclear charges and the structure of electronic shells. Currently, 118 elements are known: 89 of them are found in nature (on Earth), the rest are obtained artificially. Atoms exist in a free state, in compounds with atoms of the same or other elements, forming molecules. The ability of atoms to interact with other atoms and form chemical compounds is determined by its structure. Atoms consist of a positively charged nucleus and negatively charged electrons moving around it, forming an electrically neutral system that obeys the laws characteristic of microsystems.

Atomic nucleus - the central part of the atom, consisting of Zprotons and N neutrons, in which the bulk of the atoms are concentrated.

Core charge - positive, equal in value to the number of protons in the nucleus or electrons in a neutral atom and coincides with the atomic number of the element in the periodic table.

The sum of the protons and neutrons of an atomic nucleus is called the mass number A = Z+ N.

Isotopes - chemical elements with identical nuclear charges, but different mass numbers due to different numbers of neutrons in the nucleus.

Mass number ® Charge ® kernels

A Z

63 29

Cu and

65 29

35 17

Cl and

37 17

Chemical formula - this is a conventional notation of the composition of a substance using chemical symbols (proposed in 1814 by J. Berzelius) and indices (index is the number at the bottom right of the symbol. Indicates the number of atoms in the molecule). The chemical formula shows which atoms of which elements and in what ratio are connected to each other in a molecule.

Allotropy - the phenomenon of the formation by a chemical element of several simple substances that differ in structure and properties. Simple substances - molecules, consist of atoms of the same element.

Cfalse substances - molecules consist of atoms of various chemical elements.

Atomic mass constant equal to 1/12 of the mass of isotope 12 C - the main isotope of natural carbon.

m u = 1 / 12 m (12 C ) =1 a.u.m = 1.66057 10 -24 g

Relative atomic mass (A r) - dimensionless quantity equal to the ratio of the average mass of an atom of an element (taking into account the percentage of isotopes in nature) to 1/12 of the mass of an atom 12 C.

Average absolute atomic mass (m) equal to the relative atomic mass times the amu.

Ar(Mg) = 24.312

m(Mg) = 24.312 1.66057 10 -24 = 4.037 10 -23 g

Relative molecular weight (M r) - a dimensionless quantity showing how many times the mass of a molecule of a given substance is greater than 1/12 the mass of a carbon atom 12 C.

M g = m g / (1/12 m a (12 C))

m r - mass of a molecule of a given substance;

m a (12 C) - mass of a carbon atom 12 C.

M g = S A g (e). The relative molecular mass of a substance is equal to the sum of the relative atomic masses of all elements, taking into account the indices.

Examples.

M g (B 2 O 3) = 2 A r (B) + 3 A r (O) = 2 11 + 3 16 = 70

M g (KAl(SO 4) 2) = 1 A r (K) + 1 A r (Al) + 1 2 A r (S) + 2 4 A r (O) =
= 1 39 + 1 27 + 1 2 32 + 2 4 16 = 258

Absolute molecular mass equal to the relative molecular mass multiplied by the amu. The number of atoms and molecules in ordinary samples of substances is very large, therefore, when characterizing the amount of a substance, a special unit of measurement is used - the mole.

Amount of substance, mol . Means certain number structural elements (molecules, atoms, ions). Designatedn , measured in moles. A mole is the amount of a substance containing as many particles as there are atoms in 12 g of carbon.

Avogadro's number (N A ). The number of particles in 1 mole of any substance is the same and equals 6.02 10 23. (Avogadro's constant has the dimension - mol -1).

Example.

How many molecules are there in 6.4 g of sulfur?

The molecular weight of sulfur is 32 g/mol. We determine the amount of g/mol of substance in 6.4 g of sulfur:

n (s) = m(s)/M(s ) = 6.4 g / 32 g/mol = 0.2 mol

Let's determine the number of structural units (molecules) using the constant Avogadro N A

N(s) = n (s)N A = 0.2 6.02 10 23 = 1.2 10 23

Molar mass shows the mass of 1 mole of a substance (denotedM).

M = m / n

The molar mass of a substance is equal to the ratio of the mass of the substance to the corresponding amount of the substance.

The molar mass of a substance is numerically equal to its relative molecular mass, however, the first quantity has the dimension g/mol, and the second is dimensionless.

M = N A m (1 molecule) = N A M g 1 amu = (N A 1 amu) M g = M g

This means that if the mass of a certain molecule is, for example, 80 amu. ( SO 3 ), then the mass of one mole of molecules is equal to 80 g. Avogadro’s constant is a proportionality coefficient that ensures the transition from molecular relationships to molar ones. All statements regarding molecules remain valid for moles (with replacement, if necessary, of amu by g). For example, the reaction equation: 2 Na + Cl 2 2 NaCl , means that two sodium atoms react with one chlorine molecule or, which is the same thing, two moles of sodium react with one mole of chlorine.

TUTORIAL

In the discipline "General and inorganic chemistry"

Collection of lectures on general and inorganic chemistry

General and inorganic chemistry: tutorial/ author E.N.Mozzhukhina;

GBPOU "Kurgan Basic Medical College". - Kurgan: KBMK, 2014. - 340 p.

Published by decision of the editorial and publishing council of the State Autonomous Educational Institution of Further Professional Education "Institute for the Development of Education and Social Technologies"

Reviewer: NOT. Gorshkova - candidate biological sciences, Deputy Director for IMR, Kurgan Basic Medical College

Introduction.
SECTION 1. Theoretical basis chemistry	8-157
1.1. Periodic law and periodic system by element D.I. Mendeleev. Theory of the structure of substances.
1.2.Electronic structure of atoms of elements.
1.3. Types of chemical bonds.
1..4 Structure of substances of inorganic nature
1 ..5 Classes of inorganic compounds.
1.5.1. Classification, composition, nomenclature of oxides, acids, bases. Methods of preparation and their chemical properties.
1.5.2 Classification, composition, nomenclature of salts. Preparation methods and their chemical properties
1.5.3. Amphoteric. Chemical properties of amphoteric ixides and hydroxides. Genetic relationships between classes of inorganic compounds.
1..6 Complex connections.
1..7 Solutions.
1.8. Theory of electrolytic dissociation.
1.8.1. Electrolytic dissociation. Basic provisions. TED. Dissociation mechanism.
1.8.2. Ionic reactions exchange. Hydrolysis of salts.
1.9. Chemical reactions.
1.9.1. Classification of chemical reactions. Chemical equilibrium and displacement.
1.9.2. Redox reactions. Their electronic essence. Classification and compilation of OVR equations.
1.9.3. The most important oxidizing and reducing agents. ORR with the participation of dichromate, potassium permanganate and dilute acids.
1.9.4 Methods for arranging coefficients in OVR
SECTION 2. Chemistry of elements and their compounds.
2.1. P-elements.
2.1.1. general characteristics elements of group VII of the periodic table. Halogens. Chlorine, its physical and chemical properties.
2.1.2. Halides. Biological role of halogens.
2.1.3. Chalcogens. General characteristics of elements of group VI PS D.I. Mendeleev. Oxygen compounds.
2.1.4. The most important sulfur compounds.
2.1.5. Main subgroup of group V. General characteristics. Atomic structure, physical and chemical properties of nitrogen. The most important nitrogen compounds.
2.1.6. The structure of the phosphorus atom, its physical and chemical properties. Allotropy. The most important phosphorus compounds.
2.1.7. General characteristics of the elements of group IV of the main subgroup of the periodic system D.I. Mendeleev. Carbon and silicon.
2.1.8. Main subgroup of group III of the periodic system D.I. Mendeleev. Bor. Aluminum.
2.2. s - elements.
2.2.1. General characteristics of metals of group II of the main subgroup of the periodic system D.I. Mendeleev. Alkaline earth metals.
2.2.2. General characteristics of elements of group I of the main subgroup of the periodic system D.I. Mendeleev. Alkali metals.
2.3. d-elements.
2.3.1. Side subgroup of group I.
2.3.2.. Side subgroup of group II.
2.3.3. Side subgroup of group VI
2.3.4. Side subgroup of group VII
2.3.5. Side subgroup of group VIII

Explanatory note

At the present stage of development of society, the primary task is to take care of human health. The treatment of many diseases has become possible thanks to advances in chemistry in the creation of new substances and materials.

Without deep and comprehensive knowledge in the field of chemistry, without knowing the meaning of positive or negative influence chemical factors on environment, you will not be able to be a competent medical worker. Medical college students must have the required minimum knowledge of chemistry.

This course of lecture material is intended for students studying the basics of general and inorganic chemistry.

The purpose of this course is to study the principles of inorganic chemistry presented at the current level of knowledge; expanding the scope of knowledge taking into account professional orientation. An important direction is to create a solid base on which to build the teaching of other chemical special disciplines(organic and analytical chemistry, pharmacology, drug technology).

The proposed material provides professional orientation for students on the connection between theoretical inorganic chemistry and special and medical disciplines.

The main objectives of the training course of this discipline are to master the fundamental principles of general chemistry; in students’ assimilation of the content of inorganic chemistry as a science that explains the connection between the properties of inorganic compounds and their structure; in the formation of ideas about inorganic chemistry as a fundamental discipline on which professional knowledge is based.

The course of lectures on the discipline “General and Inorganic Chemistry” is built in accordance with the requirements of the State educational standard(FSES-4) to the minimum level of training of graduates in specialty 060301 “Pharmacy” and is developed on the basis of the curriculum of this specialty.

The course of lectures includes two sections;

1. Theoretical foundations of chemistry.

2. Chemistry of elements and their compounds: (p-elements, s-elements, d-elements).

Presentation educational material presented in development: from the most simple concepts to complex, holistic, generalizing.

The section “Theoretical Foundations of Chemistry” covers the following issues:

1. Periodic law and the Periodic table of chemical elements D.I. Mendeleev and the theory of the structure of substances.

2. Classes of inorganic substances, the relationship between all classes of inorganic substances.

3. Complex compounds, their use in qualitative analysis.

4. Solutions.

5. Theory of electrolytic dissociation.

6. Chemical reactions.

When studying the section “Chemistry of elements and their compounds” the following questions are considered:

1. Characteristics of the group and subgroup in which this element is located.

2. Characteristics of an element, based on its position in the periodic table, from the point of view of the theory of atomic structure.

3. Physical properties and distribution in nature.

4. Methods of obtaining.

5. Chemical properties.

6. Important connections.

7. Biological role of the element and its use in medicine.

Special attention is devoted to medicines of inorganic nature.

As a result of studying this discipline, the student should know:

1. Periodic law and characteristics of the elements of the periodic system D.I. Mendeleev.

2. Fundamentals of the theory of chemical processes.

3. Structure and reactivity of substances of inorganic nature.

4. Classification and nomenclature of inorganic substances.

5. Preparation and properties of inorganic substances.

6. Application in medicine.

1. Classify inorganic compounds.

2. Make up names of compounds.

3. Install genetic connection between inorganic compounds.

4. Using chemical reactions, prove the chemical properties of inorganic substances, including medicinal ones.

Lecture No. 1

Topic: Introduction.

1. Subject and tasks of chemistry

2. Methods of general and inorganic chemistry

3. Fundamental theories and laws of chemistry:

a) atomic-molecular theory.

b) the law of conservation of mass and energy;

c) periodic law;

d) theory of chemical structure.

inorganic chemistry.

1. Subject and tasks of chemistry

Modern chemistry is one of the natural sciences and is a system of individual disciplines: general and inorganic chemistry, analytical chemistry, organic chemistry, physical and colloidal chemistry, geochemistry, cosmochemistry, etc.

Chemistry is a science that studies the processes of transformation of substances, accompanied by changes in composition and structure, as well as mutual transitions between these processes and other forms of movement of matter.

Thus, the main object of chemistry as a science is substances and their transformations.

At the present stage of development of our society, caring for human health is a task of paramount importance. The treatment of many diseases has become possible thanks to advances in chemistry in the creation of new substances and materials: medicines, blood substitutes, polymers and polymeric materials.

Without deep and comprehensive knowledge in the field of chemistry, without understanding the significance of the positive or negative impact of various chemical factors on human health and the environment, it is impossible to become a competent medical professional.

general chemistry. Inorganic chemistry.

Inorganic chemistry is the science of the elements of the periodic table and the simple and complex substances formed by them.

Inorganic chemistry is inseparable from general chemistry. Historically, when studying the chemical interaction of elements with each other, the basic laws of chemistry, general patterns of chemical reactions, the theory of chemical bonds, the doctrine of solutions, and much more were formulated, which constitute the subject of general chemistry.

Thus, general chemistry studies the theoretical ideas and concepts that form the foundation of the entire system of chemical knowledge.

Inorganic chemistry has long ago surpassed the stage of descriptive science and is currently experiencing its “rebirth” as a result of the widespread use of quantum chemical methods and the band model energy spectrum electrons, discoveries of valence chemical compounds noble gases, targeted synthesis of materials with special physical and chemical properties. Based on an in-depth study of the relationship between chemical structure and properties, she successfully solves main task- creation of new inorganic substances with specified properties.

2. Methods of general and inorganic chemistry.

Of the experimental methods of chemistry, the most important is the method of chemical reactions. A chemical reaction is the transformation of one substance into another by changing the composition and chemical structure. Chemical reactions make it possible to study the chemical properties of substances. By the chemical reactions of the substance under study, one can indirectly judge its chemical structure. Direct methods for determining the chemical structure are mostly based on the use of physical phenomena.

Inorganic synthesis is also carried out on the basis of chemical reactions, which Lately achieved great success, especially in obtaining highly pure compounds in the form of single crystals. This was facilitated by the use of high temperatures and pressures, high vacuum, the introduction of containerless cleaning methods, etc.

When carrying out chemical reactions, as well as when isolating substances from a mixture in their pure form important role Preparative methods play a role: precipitation, crystallization, filtration, sublimation, distillation, etc. Currently, many of these classical preparative methods have been further developed and are leading in the technology for obtaining highly pure substances and single crystals. These are methods of directed crystallization, zone recrystallization, vacuum sublimation, fractional distillation. One of the features of modern inorganic chemistry is the synthesis and study of highly pure substances on single crystals.

Methods of physicochemical analysis are widely used in the study of solutions and alloys, when the compounds formed in them are difficult or practically impossible to isolate in an individual state. Then the physical properties of the systems are studied depending on the change in composition. As a result, a composition-properties diagram is constructed, analysis of which allows one to draw a conclusion about the nature of the chemical interaction of the components, the formation of compounds and their properties.

To understand the essence of a phenomenon, experimental methods alone are not enough, so Lomonosov said that a true chemist must be a theoretician. Only through thinking, scientific abstraction and generalization are the laws of nature learned and hypotheses and theories created.

Theoretical understanding of experimental material and the creation of a coherent system of chemical knowledge in modern general and inorganic chemistry is based on: 1) quantum mechanical theory of the structure of atoms and the periodic system of elements by D.I. Mendeleev; 2) quantum chemical theory of chemical structure and the doctrine of the dependence of the properties of a substance on “its chemical structure; 3) the doctrine of chemical equilibrium, based on the concepts of chemical thermodynamics.

3. Fundamental theories and laws of chemistry.

The fundamental generalizations of chemistry and natural science include atomic-molecular theory, the law of conservation of mass and energy,

Periodic table and theory of chemical structure.

a) Atomic-molecular theory.

The creator of atomic-molecular studies and the discoverer of the law of conservation of mass of substances M.V. Lomonosov is rightfully considered the founder of scientific chemistry. Lomonosov clearly distinguished two stages in the structure of matter: elements (in our understanding - atoms) and corpuscles (molecules). According to Lomonosov, molecules of simple substances consist of identical atoms, and molecules of complex substances consist of different atoms. The atomic-molecular theory received general recognition in early XIX centuries after Dalton's atomism was established in chemistry. Since then, molecules have become the main object of chemistry research.

b) Law of conservation of mass and energy.

In 1760, Lomonosov formulated a unified law of mass and energy. But before the beginning of the 20th century. these laws were considered independently of each other. Chemistry mainly dealt with the law of conservation of mass of a substance (the mass of substances that entered into a chemical reaction is equal to the mass of substances formed as a result of the reaction).

For example: 2KlO 3 = 2 KCl + 3O 2

Left: 2 potassium atoms Right: 2 potassium atoms

2 chlorine atoms 2 chlorine atoms

6 oxygen atoms 6 oxygen atoms

Physics dealt with the law of conservation of energy. In 1905, the founder of modern physics A. Einstein showed that there is a relationship between mass and energy, expressed by the equation E = mс 2, where E is energy, m is mass; c is the speed of light in vacuum.

c) Periodic law.

The most important task of inorganic chemistry is to study the properties of elements, to identify general patterns their chemical interaction with each other. The largest scientific generalization in solving this problem was made by D.I. Mendeleev, who discovered the Periodic Law and its graphic expression - the Periodic System. Only as a result of this discovery did chemical foresight, the prediction of new facts, become possible. Therefore, Mendeleev is the founder of modern chemistry.

Mendeleev's periodic law is the basis of natural
taxonomy of chemical elements. Chemical element - collection
atoms with the same nuclear charge. Patterns of property changes
chemical elements are determined by the Periodic Law. Doctrine of
the structure of atoms explained the physical meaning of the Periodic Law.
It turned out that the frequency of changes in the properties of elements and their compounds
depends on a periodically repeating similar electronic structure
shells of their atoms. Chemical and some physical properties depend on
the structure of the electronic shell, especially its outer layers. That's why
The periodic law is the scientific basis for the study of the most important properties of elements and their compounds: acid-base, redox, catalytic, complexing, semiconductor, metallochemical, crystal chemical, radiochemical, etc.

The periodic table also played a colossal role in the study of natural and artificial radioactivity and the release of intranuclear energy.

The periodic law and the periodic system are continuously developing and being refined. Proof of this is the modern formulation of the Periodic Law: the properties of elements, as well as the forms and properties of their compounds, are periodically dependent on the magnitude of the charge of the nucleus of their atoms. Thus, the positive charge of the nucleus, rather than the atomic mass, turned out to be a more accurate argument on which the properties of elements and their compounds depend.

d) Theory of chemical structure.

The fundamental task of chemistry is to study the relationship between the chemical structure of a substance and its properties. The properties of a substance are a function of its chemical structure. Before A.M. Butlerov believed that the properties of a substance are determined by its qualitative and quantitative composition. He first formulated the basic principles of his theory of chemical structure. Thus: the chemical nature of a complex particle is determined by the nature of the elementary constituent particles, their quantity and chemical structure. Translated into modern language this means that the properties of a molecule are determined by the nature of its constituent atoms, their number and the chemical structure of the molecule. Originally, the theory of chemical structure referred to chemical compounds that had a molecular structure. Currently, the theory created by Butlerov is considered a general chemical theory of the structure of chemical compounds and the dependence of their properties on their chemical structure. This theory is a continuation and development of Lomonosov’s atomic-molecular teachings.

4. The role of domestic and foreign scientists in the development of general and

inorganic chemistry.

p/p	Scientists	Dates of life	The most important works and discoveries in the field of chemistry
1.	Avogadro Amedo (Italy) |	1776-1856	Avogadro's Law 1
2.	Arrhenius Svante (Sweden)	1859-1927	Electrolytic dissociation theory
3.	Beketov N.N. (Russia)	1827-1911	Metal activity series. Basics of aluminothermy.
4.	Berthollet Claude Louis (France)	1748-1822	Conditions for the flow of chemical reactions. Gas research. Bertholet's salt.
5.	Berzelius Jene Jakob (Sweden)	1779-1848	Determination of atomic weights of elements. Introduction of letter designations for chemical elements.
6.	Boyle Robert (England)	1627-1691	Establishing the concept of a chemical element. Dependence of gas volumes on pressure.
7.	Bor Nils (Denmark)	1887-1962	Theory of atomic structure. 1
8.	Van't Hoff Jacob Gendrik (Holland)	1852-1911	Study of solutions; one of the founders of physical chemistry and stereochemistry.
9.	Gay-Lussac Joseph (France)	1778-1850	Gay-Lussac's gas laws. Study of oxygen-free acids; sulfuric acid technology.
10.	Hess German Ivanov (Russia)	1802-1850	Discovery of the fundamental law of thermochemistry. Development of Russian chemical nomenclature. Mineral analysis.
11.	Dalton John (England)	1766-1844	Law of multiple ratios. Introduction of chemical symbols and formulas. Justification of the atomic theory.
12.	Maria Curie-Skłodowska (France, native Poland)	1867-1934	Discovery of polonium and radium; study of the properties of radioactive substances. Release of metallic radium.
13.	Lavoisier Antoine Laurent (France)	1743-1794	The foundation of scientific chemistry, the establishment of the oxygen theory of combustion, the nature of water. Creation of a chemistry textbook based on new views.
14.	Le Chatelier Lune Henri (France)	1850-1936	General law equilibrium shifts depending on external conditions (Le Chatelier's principle)
15.	Lomonosov Mikhail Vasilievich	1741-1765	Law of conservation of mass of substances.
			Application of quantitative methods in chemistry; development of the basic principles of the kinetic theory of gases. Founding of the first Russian chemical laboratory. Drawing up a manual on metallurgy and mining. Creation of mosaic production.
16.	Mendeleev Dmitry Ivanovich (Russia)	1834-1907	The periodic law and the periodic table of chemical elements (1869). Hydrate theory solutions. "Fundamentals of Chemistry". Research of gases, discovery of critical temperature, etc.
17.	Priestley Joseph (England)	1733-1804	Discovery and research of oxygen, hydrogen chloride, ammonia, carbon monoxide, nitrogen oxide and other gases.
18.	Rutherford Ernest (England)	1871-1937	Planetary theory of atomic structure. Evidence of spontaneous radioactive decay with the release of alpha, beta, and gamma rays.
19.	Jacobi Boris Semenovich (Russia)	1801-1874	The discovery of galvanoplasty and its introduction into the practice of printing and coinage.
20.	And others

Questions for self-control:

1. The main tasks of general and inorganic chemistry.

2. Methods of chemical reactions.

3. Preparative methods.

4. Methods of physical and chemical analysis.

5. Basic laws.

6. Basic theories.

Lecture No. 2

Topic: “Structure of the atom and the periodic law of D.I. Mendeleev"

Plan

1. Atomic structure and isotopes.

2. Quantum numbers. Pauli's principle.

3. The periodic table of chemical elements in the light of the theory of atomic structure.

4. Dependence of the properties of elements on the structure of their atoms.

Periodic law D.I. Mendeleev discovered the mutual relationship of chemical elements. The study of the periodic law raised a number of questions:

1. What is the reason for the similarities and differences between the elements?

2. What explains the periodic change in the properties of elements?

3. Why do neighboring elements of the same period differ significantly in properties, although their atomic masses differ by a small amount, and vice versa, in subgroups the difference in atomic masses of neighboring elements is large, but the properties are similar?

4. Why is the arrangement of elements in order of increasing atomic masses violated by the elements argon and potassium; cobalt and nickel; tellurium and iodine?

Most scientists recognized the real existence of atoms, but adhered to metaphysical views (an atom is the smallest indivisible particle of matter).

IN late XIX the complex structure of the atom and the possibility of transforming some atoms into others under certain conditions were established. The first particles discovered in an atom were electrons.

It was known that with strong incandescence and UV illumination from the surface of metals, negative electrons and metals become positively charged. In elucidating the nature of this electricity, the work of the Russian scientist A.G. was of great importance. Stoletov and the English scientist W. Crookes. In 1879, Crookes investigated the phenomena of electron rays in magnetic and electric fields under the influence of high voltage electric current. The property of cathode rays to set bodies in motion and experience deviations in magnetic and electric fields made it possible to conclude that these are material particles that carry the smallest negative charge.

In 1897, J. Thomson (England) investigated these particles and called them electrons. Since electrons can be obtained regardless of the substance of which the electrodes are composed, this proves that electrons are part of the atoms of any element.

In 1896, A. Becquerel (France) discovered the phenomenon of radioactivity. He discovered that uranium compounds have the ability to emit invisible rays that act on a photographic plate wrapped in black paper.

In 1898, continuing Becquerel's research, M. Curie-Skladovskaya and P. Curie discovered two new elements in uranium ore - radium and polonium, which have very high radiation activity.

radioactive element

The property of atoms of various elements to spontaneously transform into atoms of other elements, accompanied by the emission of alpha, beta and gamma rays invisible to the naked eye, is called radioactivity.

Consequently, the phenomenon of radioactivity is direct evidence of the complex structure of atoms.

Electrons are integral part atoms of all elements. But the electrons are negatively charged, and the atom as a whole is electrically neutral, then, obviously, inside the atom there is a positively charged part, which with its charge compensates for the negative charge of the electrons.

Experimental data on the presence of a positively charged nucleus and its location in the atom were obtained in 1911 by E. Rutherford (England), who proposed a planetary model of the structure of the atom. According to this model, an atom consists of a positively charged nucleus, very small in size. Almost all the mass of an atom is concentrated in the nucleus. The atom as a whole is electrically neutral, therefore, the total charge of the electrons must be equal to the charge of the nucleus.

Research by G. Moseley (England, 1913) showed that the positive charge of an atom is numerically equal to the atomic number of the element in the periodic table of D.I. Mendeleev.

So, the serial number of an element indicates the number of positive charges of the atomic nucleus, as well as the number of electrons moving in the field of the nucleus. This is the physical meaning of the element's serial number.

According to the nuclear model, the hydrogen atom has the simplest structure: the nucleus carries one elementary positive charge and a mass close to unity. It is called a proton (“simplest”).

In 1932, physicist D.N. Chadwick (England) found that the rays emitted when an atom is bombarded with alpha particles have enormous penetrating ability and represent a stream of electrically neutral particles - neutrons.

Based on the study of nuclear reactions by D.D. Ivanenko (physicist, USSR, 1932) and at the same time W. Heisenberg (Germany) formulated the proton-neutron theory of the structure of atomic nuclei, according to which atomic nuclei consist of positively charged particles-protons and neutral particles-neutrons (1 P) - the proton has relative mass 1 and relative charge + 1. 1

(1 n) – the neutron has a relative mass of 1 and charge of 0.

Thus, the positive charge of the nucleus is determined by the number of protons in it and is equal to the atomic number of the element in the PS; mass number – A (relative mass of the nucleus) is equal to the sum of protons (Z) neutrons (N):

A = Z + N; N=A-Z

Isotopes

Atoms of the same element that have the same nuclear charge and different mass numbers are isotopes. For isotopes of one element same number protons, but different number neutrons.

Hydrogen isotopes:

1 H 2 H 3 H 3 – mass number

1 - nuclear charge

protium deuterium tritium

Z = 1 Z = 1 Z =1

N=0 N=1 N=2

1 proton 1 proton 1 proton

0 neutrons 1 neutron 2 neutrons

Isotopes of the same element have the same chemical properties and are designated by the same chemical symbol and occupy one place in the P.S. Since the mass of an atom is practically equal to the mass of the nucleus (the mass of electrons is negligible), each isotope of an element is characterized, like the nucleus, by a mass number, and the element by atomic mass. The atomic mass of an element is the arithmetic mean between the mass numbers of the isotopes of an element, taking into account the percentage of each isotope in nature.

The nuclear theory of atomic structure proposed by Rutherford became widespread, but later researchers encountered a number of fundamental difficulties. According to classical electrodynamics, an electron should radiate energy and move not in a circle, but along a spiral curve and eventually fall onto the nucleus.

In the 20s of the XX century. Scientists have established that the electron has a dual nature, possessing the properties of a wave and a particle.

The mass of the electron is 1 ___ mass of hydrogen, relative charge

is equal to (-1) . The number of electrons in an atom is equal to the atomic number of the element. The electron moves throughout the entire volume of the atom, creating an electron cloud with an uneven negative charge density.

The idea of ​​the dual nature of the electron led to the creation of the quantum mechanical theory of the structure of the atom (1913, Danish scientist N. Bohr). The main thesis of quantum mechanics is that microparticles have a wave nature, and waves have the properties of particles. Quantum mechanics considers the probability of an electron being in the space around a nucleus. The region where an electron is most likely to be found in an atom (≈ 90%) is called the atomic orbital.

Each electron in an atom occupies a specific orbital and forms an electron cloud, which is a collection of different positions of a rapidly moving electron.

The chemical properties of elements are determined by the structure of the electronic shells of their atoms.

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