Inorganic chemistry is part of general chemistry. She studies the properties and behavior of inorganic compounds - their structure and ability to react with other substances. This direction studies all substances, with the exception of those built from carbon chains (the latter are the subject of the study of organic chemistry).
Description
Chemistry is a complex science. Its division into categories is purely arbitrary. For example, inorganic and organic chemistry are linked by compounds called bioinorganic. These include hemoglobin, chlorophyll, vitamin B 12 and many enzymes.
Very often, when studying substances or processes, it is necessary to take into account various relationships with other sciences. General and inorganic chemistry covers the simple ones, which number close to 400,000. The study of their properties often includes a wide range of methods of physical chemistry, since they can combine properties characteristic of a science such as physics. The qualities of substances are affected by conductivity, magnetic and optical activity, the effect of catalysts and other “physical” factors.
Generally, inorganic compounds are classified according to their function:
- acids;
- grounds;
- oxides;
- salt.
Oxides are often divided into metals (basic oxides or basic anhydrides) and non-metallic oxides (acid oxides or acid anhydrides).
Origin
The history of inorganic chemistry is divided into several periods. At the initial stage, knowledge was accumulated through random observations. Since ancient times, attempts have been made to transform base metals into precious ones. The alchemical idea was propagated by Aristotle through his doctrine of the convertibility of elements.
In the first half of the fifteenth century, epidemics raged. The population especially suffered from smallpox and plague. Aesculapians assumed that diseases were caused by certain substances, and they should be combated with the help of other substances. This led to the beginning of the so-called medico-chemical period. At that time, chemistry became an independent science.
The emergence of a new science
During the Renaissance, chemistry began to become overgrown with theoretical concepts from a purely practical field of study. Scientists tried to explain the deep processes occurring with substances. In 1661, Robert Boyle introduced the concept of "chemical element". In 1675, Nicholas Lemmer separated the chemical elements of minerals from plants and animals, thereby making it possible for chemistry to study inorganic compounds separately from organic ones.
Later, chemists tried to explain the phenomenon of combustion. The German scientist Georg Stahl created the phlogiston theory, according to which a combustible body rejects a non-gravitational phlogiston particle. In 1756, Mikhail Lomonosov experimentally proved that the combustion of some metals is associated with air (oxygen) particles. Antoine Lavoisier also disproved the theory of phlogistons, becoming the founder of the modern theory of combustion. He also introduced the concept of “combination of chemical elements.”
Development
The next period begins with work and attempts to explain chemical laws through the interaction of substances at the atomic (microscopic) level. The first chemical congress in Karlsruhe in 1860 defined the concepts of atom, valence, equivalent and molecule. Thanks to the discovery of the periodic law and the creation of the periodic system, Dmitri Mendeleev proved that atomic-molecular theory is associated not only with chemical laws, but also with the physical properties of elements.
The next stage in the development of inorganic chemistry is associated with the discovery of radioactive decay in 1876 and the elucidation of the structure of the atom in 1913. Research by Albrecht Kessel and Gilbert Lewis in 1916 solves the problem of the nature of chemical bonds. Based on the theory of heterogeneous equilibrium of Willard Gibbs and Henrik Rosseb, Nikolai Kurnakov in 1913 created one of the main methods of modern inorganic chemistry - physicochemical analysis.
Fundamentals of Inorganic Chemistry
Inorganic compounds occur in nature in the form of minerals. The soil may contain iron sulfide, such as pyrite, or calcium sulfate in the form of gypsum. Inorganic compounds also occur as biomolecules. They are synthesized for use as catalysts or reagents. The first important artificial inorganic compound is ammonium nitrate, used to fertilize the soil.
Salts
Many inorganic compounds are ionic compounds, consisting of cations and anions. These are the so-called salts, which are the object of research in inorganic chemistry. Examples of ionic compounds are:
- Magnesium chloride (MgCl 2), which contains Mg 2+ cations and Cl - anions.
- Sodium oxide (Na 2 O), which consists of Na + cations and O 2- anions.
In each salt, the proportions of ions are such that the electric charges are in equilibrium, that is, the compound as a whole is electrically neutral. Ions are described by their oxidation state and ease of formation, which follows from the ionization potential (cations) or electron affinity (anions) of the elements from which they are formed.
Inorganic salts include oxides, carbonates, sulfates and halides. Many compounds are characterized by high melting points. Inorganic salts are usually solid crystalline formations. Another important feature is their solubility in water and ease of crystallization. Some salts (for example, NaCl) are highly soluble in water, while others (for example, SiO2) are almost insoluble.
Metals and alloys
Metals such as iron, copper, bronze, brass, aluminum are a group of chemical elements on the lower left side of the periodic table. This group includes 96 elements that are characterized by high thermal and electrical conductivity. They are widely used in metallurgy. Metals can be divided into ferrous and non-ferrous, heavy and light. By the way, the most used element is iron; it accounts for 95% of global production among all types of metals.
Alloys are complex substances made by melting and mixing two or more metals in a liquid state. They consist of a base (dominant elements in percentage: iron, copper, aluminum, etc.) with small additions of alloying and modifying components.
Humanity uses about 5,000 types of alloys. They are the main materials in construction and industry. By the way, there are also alloys between metals and non-metals.
Classification
In the table of inorganic chemistry, metals are distributed into several groups:
- 6 elements are in the alkaline group (lithium, potassium, rubidium, sodium, francium, cesium);
- 4 - in alkaline earth (radium, barium, strontium, calcium);
- 40 - in transition (titanium, gold, tungsten, copper, manganese, scandium, iron, etc.);
- 15 - lanthanides (lanthanum, cerium, erbium, etc.);
- 15 - actinides (uranium, actinium, thorium, fermium, etc.);
- 7 - semimetals (arsenic, boron, antimony, germanium, etc.);
- 7 - light metals (aluminum, tin, bismuth, lead, etc.).
Nonmetals
Nonmetals can be either chemical elements or chemical compounds. In a free state, they form simple substances with non-metallic properties. In inorganic chemistry there are 22 elements. These are hydrogen, boron, carbon, nitrogen, oxygen, fluorine, silicon, phosphorus, sulfur, chlorine, arsenic, selenium, etc.
The most typical nonmetals are halogens. In reaction with metals they form which are mainly ionic, for example KCl or CaO. When interacting with each other, nonmetals can form covalently bonded compounds (Cl3N, ClF, CS2, etc.).
Bases and acids
Bases are complex substances, the most important of which are water-soluble hydroxides. When dissolved, they dissociate with metal cations and hydroxide anions, and their pH is greater than 7. Bases can be thought of as the chemical opposite of acids because water-dissociating acids increase the concentration of hydrogen ions (H3O+) until the base decreases.
Acids are substances that participate in chemical reactions with bases, taking electrons from them. Most acids of practical importance are water-soluble. When dissolved, they dissociate from hydrogen cations (H+) and acidic anions, and their pH is less than 7.
Inorganic chemistry.
Inorganic chemistry is a branch of chemistry that studies the properties of various chemical elements and the compounds they form, with the exception of hydrocarbons (chemical compounds of carbon and hydrogen) and their substitution products, which are so-called organic molecules.
The first studies in the field of inorganic chemistry were devoted to minerals. The goal was to extract various chemical elements from them. These studies made it possible to divide all substances into two large categories: chemical elements and compounds.
Chemical elements are substances consisting of identical atoms (for example, Fe, from which an iron rod is made, or Pb, from which a lead pipe is made).
Chemical compounds are substances made up of different atoms. For example, water H20, sodium sulfate Na2S04, ammonium hydroxide NH4OH...
The atoms that make up chemical elements and compounds are divided into two classes - metal atoms and non-metal atoms.
Atoms of nonmetals (nitrogen N, oxygen O, sulfur S, chlorine CI.) have the ability to attach electrons to themselves, taking them from other atoms. Therefore, non-metal atoms are called “electronegative”.
Metal atoms, on the other hand, tend to give up electrons to other atoms. Therefore, metal atoms are called electropositive. These are, for example, iron Fe, lead Pb, copper Cu, zinc Zn. Substances consisting of two different chemical elements usually contain metal atoms of one type (the designation of the corresponding atom is placed at the beginning of the chemical formula) and non-metal atoms of the same type (in the chemical formula the designation of the corresponding atom is placed after the metal atom). For example, sodium chloride NaCI. If the substance does not contain a metal atom, then the least electronegative element, for example ammonia NH3, is placed at the beginning of the chemical formula.
The naming system for inorganic chemical compounds was approved in 1960 by the International Union IUPAC. Inorganic chemical compounds are named by first pronouncing the name of the most electronegative element (usually a nonmetal). For example, a compound with the chemical formula KCI is called potassium chloride. The substance H2S is called hydrogen sulfide, and CaO is called calcium oxide.
Organic chemistry.
At the beginning of its development, this chemistry studied substances included in living organisms - plants and animals (proteins, fats, sugars), or substances of decomposed living matter (oil). All these substances were called organic.
Naturally occurring organic substances belong to various groups: oil and its components, proteins, carbohydrates, fats, hormones, vitamins and others.
At the beginning of the 19th century, the first artificial organic molecules were synthesized. Using the inorganic salt ammonium cyanate, Wöhler obtained urea in 1828. Acetic acid was synthesized by Kolbe in 1845. Berthelot obtained ethyl alcohol and formic acid (1862).
Over time, chemists learned to synthesize more and more natural organic substances. Glycerin, vanillin, caffeine, nicotine, and cholesterol were obtained.
Many of the synthesized organic substances do not exist in nature. These are plastics, detergents, artificial fibers, numerous medications, dyes, insecticides.
Carbon forms more compounds than any other element. Having a stable outer electron shell, carbon has very little tendency to become a positively or negatively charged ion. This electron shell arises as a result of the formation of four bonds directed towards the vertices of the tetrahedron, in the center of which is the nucleus of the carbon atom. This is why organic molecules have a specific structure.
In organic molecules, the carbon atom is always involved in four chemical bonds. Carbon atoms can easily combine with each other to form long chains or cyclic structures.
Carbon atoms in organic molecules can be connected to each other by single bonds (the so-called saturated hydrocarbons) or multiple, or rather double, and triple bonds (unsaturated hydrocarbons).
The International Union IUPAC has developed a naming system for organic compounds. This system reveals the longest straight carbon chain, the type of chemical bond between the carbon atoms, and the presence of different groups of atoms (substituents) attached to the main carbon chain.
Groups of carbon atoms give the organic molecules in which they are contained specific properties. The latter make it possible to distinguish between numerous classes of organic compounds, for example: hydrocarbons (substances made of carbon and hydrogen atoms), alcohols, organic acids.
/ / /UDC 546(075) BBK 24.1 i 7 0-75
Compiled by: Klimenko B.I candidate. tech. Sciences, Associate Professor Volodchsnko A N., Ph.D. tech. Sciences, Associate Professor Pavlenko V.I., Doctor of Engineering. sciences, prof.
Reviewer Gikunova I.V., Ph.D. tech. Sciences, Associate Professor
Fundamentals of inorganic chemistry: Guidelines for students 0-75 full-time education. - Belgorod: Publishing house BelGTASM, 2001. - 54 p.
The methodological instructions examine in detail, taking into account the main sections of general chemistry, the properties of the most important classes of inorganic substances. This work contains generalizations, diagrams, tables, examples, which will facilitate better assimilation of extensive factual material. Particular attention, both in the theoretical and in the practical part, is paid to the connection between inorganic chemistry and the basic concepts of general chemistry.
The book is intended for first-year students of all specialties.
UDC 546(075) BBK 24.1 i 7
© Belgorod State Technological Academy of Construction Materials (BelGTASM), 2001
INTRODUCTION
Knowledge of the foundations of any science and the problems facing it is the minimum that any person should know in order to freely navigate the world around them. Natural science plays an important role in this process. Natural science is a set of sciences about nature. All sciences are divided into exact (natural) and fine (humanities). The former study the laws of development of the material world, the latter - the laws of development and manifestation of the human mind. In the presented work, we will become familiar with the basics of one of the natural sciences, 7 inorganic chemistry. Successful study of inorganic chemistry is possible only if you know the composition and properties of the main classes of inorganic compounds. Knowing the characteristics of classes of compounds, it is possible to characterize the properties of their individual representatives.
When studying any science, including chemistry, the question always arises: where to start? From the study of factual material: descriptions of the properties of compounds, indications of the conditions for their existence, listing the reactions in which they enter; On this basis, laws governing the behavior of substances are derived or, conversely, laws are first given, and then the properties of substances are discussed on their basis. In this book we will use both methods of presenting factual material.
1. BASIC CONCEPTS OF INORGANIC CHEMISTRY
What is the subject of chemistry, what does this science study? There are several definitions of chemistry.
On the one hand, chemistry is the science of substances, their properties and transformations. On the other hand, chemistry is one of the natural sciences that studies the chemical form of the movement of matter. The chemical form of the movement of matter is the processes of association of atoms into molecules and dissociation of molecules. The chemical organization of matter can be represented by the following diagram (Fig. 1).
Rice. 1. Chemical organization of matter
Matter is an objective reality given to a person in his sensations, which is copied, photographed, displayed by our sensations, existing independently of us. Matter as an objective reality exists in two forms: in the form of matter and in the form of a field.
A field (gravitational, electromagnetic, intranuclear forces) is a form of existence of matter, which is characterized and manifested primarily by energy, and not by mass, although it has the latter. Energy is a quantitative measure of motion, expressing the ability of material objects to do work.
Mass (lat. massa - block, lump, piece) is a physical quantity, one of the main characteristics of matter, determining its inertial and gravitational properties.
An atom is the lowest level of chemical organization of matter. An atom is the smallest particle of an element that retains its properties. It consists of a positively charged nucleus and negatively charged electrons; In general, the atom is electrically neutral. Chemical element - This is a type of atom with the same nuclear charge. There are 109 known elements, of which 90 exist in nature.
A molecule is the smallest particle of a substance that has the chemical properties of that substance.
The number of chemical elements is limited, and their combinations give everything
variety of substances.
What is a substance?
In a broad sense, matter is a specific type of matter that has a rest mass and is characterized under given conditions by certain physical and chemical properties. About 600 thousand inorganic substances and about 5 million organic substances are known.
In a narrower sense, a substance is a certain set of atomic and molecular particles, their associates and aggregates, located in any of three states of aggregation.
A substance is quite fully defined by three characteristics: 1) it occupies part of the space; 2) has a rest mass;
3) built from elementary particles.
All substances can be divided into simple and complex.
ments form not one, but several simple substances. This phenomenon is called allotropy, and each of these simple substances is called an allotropic modification (modification) of a given element. Allotropy is observed in carbon, oxygen, sulfur, phosphorus and a number of other elements. Thus, graphite, diamond, carbyne and fullerenes are allotropic modifications of the chemical element carbon; red, white, black phosphorus - allotropic modifications of the chemical element phosphorus. About 400 simple substances are known.
A simple substance is a form of existence of chemicals
elements in a free state
Simple substances are divided into metals and non-metals. Whether a chemical element is a metal or non-metal can be determined using the periodic table of elements by D.I. Mendeleev. Before we do this, let's remember a little about the structure of the periodic table.
1.1. Periodic law and periodic system of D.I.Mendeleev
Periodic table of elements - this is a graphic expression of the periodic law, discovered by D.I. Mendeleev on February 18, 1869. The periodic law sounds like this: the properties of simple substances, as well as the properties of compounds, are periodically dependent on the charge of the nucleus of the atoms of the element.
There are more than 400 options for depicting the periodic table. The most common cellular variants (short variant - 8-cell and long variants - 18- and 32-cell). The short period periodic system consists of 7 periods and 8 groups.
Elements that have a similar structure of the external energy level are combined into groups. There are main (A) and secondary (B)
groups. The main groups are made up of s- and p-elements, and the secondary groups are made up of d-elements.
A period is a successive series of elements in whose atoms the same number of electron layers of the same energy level are filled. The difference in the sequence of filling the electronic layers explains the reason for the different period lengths. In this regard, the periods contain different numbers of elements: 1st period - 2 elements; 2nd and 3rd periods - 8 elements each; 4th and 5th
periods - 18 elements each and the 6th period - 32 elements.
Elements of small periods (2nd and 3rd) are classified into a subgroup of typical elements. Since the d- and / elements are filled with the 2nd and 3rd outside elgk-
location of their atoms, and therefore, a greater ability to attach electrons (oxidizing ability), transmitted by high values of their electronegativity. Elements with non-metallic properties occupy the upper right corner of the periodic table
D.I. Mendeleev. Nonmetals can be gaseous (F2, O2, CI2), solid (B, C, Si, S) and liquid (Br2).
The element hydrogen occupies a special place in the periodic table
system and has no chemical analogues. Hydrogen exhibits metallic
and non-metallic properties, and therefore in the periodic table it
placed simultaneously in group IA and VIIA.
Due to the great diversity of chemical properties, they are distinguished from
efficient noble gases(aerogens) - elements of group VIIIA |
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dic |
systems. Research in recent years allows, however, |
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it is possible to classify some of them (Kr, Xe, Rn) as non-metals. |
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A characteristic property of metals is that the valence |
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thrones are weakly bound to a particular atom, and |
inside everyone |
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there is a so-called electronic |
Therefore everything |
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have |
high electrical conductivity, |
thermal conductivity |
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accuracy. Although there are also brittle metals (zinc, antimony, bismuth). Metals, as a rule, exhibit reducing properties.
Complex substances(chemical compounds) are substances whose molecules are formed by atoms of various chemical elements (heteroatomic or heteronuclear molecules). For example, C 02, CON. More than 10 million complex substances are known.
The highest form of chemical organization of matter are associates and aggregates. Associates are combinations of simple molecules or ions into more complex substances that do not cause changes in the chemical nature. Associates exist mainly in liquid and gaseous states, and aggregates exist in solid states.
Mixtures are systems consisting of several evenly distributed compounds, interconnected by constant ratios and not interacting with each other.
1.2. Valency and oxidation state
The compilation of empirical formulas and the formation of names of chemical compounds is based on the knowledge and correct use of the concepts of oxidation state and valency.
Oxidation state- this is the conditional charge of the element in the compound, calculated from the assumption that the compound consists of ions. This value is conditional, formal, since there are practically no purely ionic compounds. The degree of oxidation in absolute value can be an integer or fractional number; and in terms of charge it can be positive, negative and equal to zero.
Valence is a quantity determined by the number of unpaired electrons at the outer energy level or the number of free atomic orbitals capable of participating in the formation of chemical bonds.
Some rules for determining the oxidation states of chemical elements
1. The oxidation state of a chemical element in a simple substance
equals 0.
2. The sum of the oxidation states of atoms in a molecule (ion) is 0
(ion charge).
3. Elements of groups I-III A have a positive oxidation state corresponding to the number of the group in which the element is located.
4. Elements of groups IV -V IIA, except for the positive oxidation state corresponding to the group number; and a negative oxidation state corresponding to the difference between the group number and the number 8, have an intermediate oxidation state equal to the difference between the group number and the number 2 (Table 1).
Table 1
Oxidation states of elements IV -V IIA subgroups
Oxidation state |
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Intermediate |
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5. The oxidation state of hydrogen is +1 if the compound contains at least one non-metal; - 1 in compounds with metals (hydrides); 0 in H2.
Hydrides of some elements
BeH2 |
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NaH MgH2 АШ3 |
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CaH2 |
GaH3 |
GeH4 |
AsH3 |
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SrH2 |
InH3 |
SnH4 |
SbH3 |
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VaN2 |
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H connections |
Intermediate |
Connections i t |
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connections |
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6. The oxidation state of oxygen, as a rule, is -2, with the exception of peroxides (-1), superoxides (-1/2), ozonides (-1/3), ozone (+4), oxygen fluoride (+2).
7. The oxidation state of fluorine in all compounds except F2> is -1. In compounds with fluorine, higher forms of oxidation of many chemical elements (BiF5, SF6, IF?, OsFg) are realized.
8 . In periods, the orbital radii of atoms decrease with increasing serial number, and the ionization energy increases. At the same time, acidic and oxidizing properties are enhanced; higher ste
Element oxidation penalties become less stable.
9. Elements of odd groups of the periodic system are characterized by odd degrees, and elements of even groups are characterized by even degrees
oxidation.
10. In the main subgroups, as the atomic number of an element increases, the sizes of atoms generally increase, and the ionization energy decreases. Accordingly, the basic properties are enhanced and the oxidizing properties are weakened. In subgroups of ^-elements with increasing atomic number, the participation of ^-electrons in the formation of bonds
decreases, and therefore decreases |
absolute value |
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no oxidation (Table 2). |
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table 2 |
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Values of oxidation states of elements of the VA subgroup |
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Oxidation state |
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Li, K, Fe, Ba |
Acid C 02, S 0 3 |
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Nonmetals |
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Amphoteric ZnO BeO |
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Amphigenes |
Double Fe304 |
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Be, AL Zn |
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ole-forming |
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Aerogens |
CO, NO, SiO, N20 |
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Bases Ba(OH)2 |
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Acids HNO3 |
HYDROXIDES |
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Ampholytes Zti(OH)2 |
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Medium KagSOz, |
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Sour ManKUz, |
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Basic (SiOH)gCO3, 4-------- |
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Double CaMg(COs)2 |
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Mixed SaSGSU |
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> w h o w J 3 w »
Fig. 2. Scheme of the most important classes of inorganic substances
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 substances (a class of compounds that includes carbon, with the exception of a few simple 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 substantiation of methods for creating new materials with the properties necessary for modern technology.
Classification of chemical elements
Periodic table of chemical elements ( Mendeleev table) - classification of chemical elements, which establishes the dependence of various properties of chemical elements on 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 system have been proposed, but in the modern version of the system, it is assumed that the elements are reduced into a two-dimensional table, in which each column (group) defines the main 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 so far, 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.
