Inorganic chemistry - what is it? Inorganic chemistry in the school curriculum

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

What it is

Inorganic chemistry is a science that considers the principles of structure, basic properties and reactivity of all elements of the periodic table. An important role in the inorganic is played by the Periodic Law, which regulates the systematic classification of substances by changing their mass, number and type.

The course covers also the compounds formed during the interaction of the elements of the table (the only exception is the hydrocarbon region considered in the chapters of the organics). The problems of inorganic chemistry make it possible to refine the theoretical knowledge obtained in practice.

Science in its historical aspect

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

Over time, it was proved that most of the organic world can produce "non-living" compounds, and hydrocarbons of any type are synthesized under laboratory conditions. So, from the ammonium cyanate, which is a salt in the chemistry of elements, the German scientist Veler was able to synthesize urea.

In order to avoid confusion with the nomenclature and classification of types of research in both sciences, the program of school and university courses following general chemistry presupposes the study of inorganics as a fundamental discipline. In the scientific world, the same sequence is preserved.

Classes of inorganic substances

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

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 the consideration of such a concept as classes of inorganic chemistry is popular. In the columns of the table, the elements are indicated depending on the physicochemical properties, in the lines - periods similar to each other.

Simple substances in inorganic

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

The chemical bond in simple substances causes their division into families. Thus, we can distinguish two broad types of groups of atoms - metals and nonmetals. The first family consists of 96 elements out of 118 studied.

Metals

The metallic type assumes the existence of the same-named bond between the particles. The interaction is based on the socialization of lattice electrons, which is characterized by non-directivity and unsaturation. That is why metals conduct heat, charges, have a metallic luster, ductility and plasticity.

Conditionally, the metals are on the left in the periodic table when carrying out a straight line from boron to astatine. Elements close in location to this point are most often borderline and exhibit a duality of properties (for example, germanium).

Metals in most form the basic compounds. The degree of oxidation of such substances usually does not exceed two. In the group, metallicity increases, but decreases in the period. For example, radioactive france exhibits more basic properties than sodium, and in the family of halogens, iodine even has a metallic luster.

Otherwise, the situation is in the period - the sublevels are terminated with inert gases, in front of which there are substances with opposite properties. In the horizontal space of the periodic table, the reactivity of the elements varies from the main through the amphoteric to the acidic. Metals are good reducing agents (they take electrons in the formation of bonds).

Non-metals

This type of atoms are included in the main classes of inorganic chemistry. Non-metals occupy the right side of Mendeleev's 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 nonmetallic gases - besides the above two, they can 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 (here also include radioactive and unstable configurations that are located in the last periods of the table).

In compounds, non-metals behave preferentially as acids. They are powerful oxidants due to the possibility of attaching an additional number of electrons to complete the level.

Complex substances in inorganic

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

Two-element substances

The special importance of the binary connection in molecules is attached by chemistry. Classes of inorganic compounds are also considered from the point of view of the bond formed between atoms. It can be ionic, metallic, covalent (polar or nonpolar), or mixed. Typically, these substances clearly show the basic (in the presence of metal), amphoteric (dual - especially characteristic of aluminum) or acidic (if there is an element with an oxidation degree of +4 or higher) quality.

Three-element associates

Themes of inorganic chemistry provide for the consideration of this kind of union of atoms. Compounds consisting of more than two groups of atoms (most often inorganics deal with three-element species) are usually formed with the participation of components that differ significantly in physico-chemical parameters.

Possible types of communication are covalent, ionic and mixed. Usually three-element substances behave similar to binary ones due to the fact that one of the forces of interatomic interaction is much stronger than the other: the weak one is formed in the second turn and has the possibility to dissociate in solution more quickly.

Classes of inorganic chemistry

The vast majority of substances studied in the course of inorganic substances can be considered by simple classification depending on their composition and properties. Thus, hydroxides, acids, oxides and salts are distinguished. Consideration of their relationship is better to begin with familiarity with the concept of oxidized forms, in which there may be almost any inorganic substances. The chemistry of such associates is discussed in the chapters on oxides.

Oxides

Oxide is the combination of any chemical element with oxygen in an oxidation state of -2 (in peroxides -1, respectively). The formation of the bond occurs due to the recoil and attachment 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 it is metal, in oxide it does not exceed the degree of oxidation +2, if non-metal - from +4 and above. In samples with a dual nature of the parameters, a value of +3 is achieved.

Inorganic acids

Acidic compounds have a reaction of less than 7 medium due to the content of hydrogen cations that can go into solution and subsequently be replaced by a metal ion. By classification are complex substances. Most acids can be obtained by diluting the corresponding oxides with water, for example, by the formation of sulfuric acid after hydration of SO ₃ .

Basic inorganic chemistry

Properties of this type of compounds are due to the presence of 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 (decay into ions in the liquid). The OH group can be replaced by acid residues when forming salts.

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

Salt

This type of compounds is located between bases and acids, since it is the product of their interaction. Thus, usually a metal ion (sometimes ammonium, phosphonium or hydroxonium) appears as a cation, and an acidic residue is an anionic substance. When the 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 medium);
• Acid salts are formed in the opposite case - with a lack of a reacting base, hydrogen partially remains in the compound;
• The most famous and easy to understand are the medium (or normal) samples - they are the product of complete neutralization of the reagents with the formation of water and matter only with the metal cation or its analog and acid residue.

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

• The double contain a single anion in the presence of two cations. Usually such substances are obtained as a result of the merging of 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, in the formula of which there is water in the crystallized state.
• Complexes are substances in which a cation, an anion or both of them are represented as clusters with a forming element. Such salts can be obtained predominantly among the elements of subgroup B.

As other substances included in the workshop on inorganic chemistry, which can be classified as salts or as separate chapters of knowledge, one can name hydrides, nitrides, carbides and intermetallides (compounds of several metals that are not 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 the school on this subject. The course of inorganic chemistry provides for the systematization of large amounts of information in accordance with an understandable and simple classification.