Chemistry course in schools begins in the 8th grade with the study of the general foundations of 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 is this
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 streamlines the systematic classification of substances by changing their mass, number and type.
The course also covers compounds formed during the interaction of the elements of the table (the only exception is the area of hydrocarbons, which is considered in the chapters of organics). Tasks in inorganic chemistry allow you to work out the theoretical knowledge gained in practice.
Science in the historicalaspect
The name "inorganic" came about 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 of the organic world can produce "non-living" compounds, and hydrocarbons of any type are synthesized in the laboratory. So, from ammonium cyanate, which is a s alt in the chemistry of the elements, the German scientist Wehler was able to synthesize urea.
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, involves the study of inorganics as a fundamental discipline. The scientific world maintains a similar sequence.
Classes of inorganic substances
Chemistry provides for such a presentation of the material, in which the introductory chapters of inorganics consider the Periodic Law of the Elements. This is a classification of 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 built 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, suggests the presence of about a hundred figures, clusters and diagrams that reflect the periodicity of properties.
Currently, a consolidated version of considering suchconcepts as classes of inorganic chemistry. The columns of the table indicate the elements depending on the physical and chemical properties, in the rows - periods 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 a specific type of atoms is reflected, in the second - the type of connection of particles and their mutual influence in stable forms.
Chemical bonding in simple substances determines their division into families. Thus, two broad types of groups of atoms can be distinguished - metals and non-metals. The first family includes 96 elements out of 118 studied.
Metals
Metal type implies the presence of the same name connection between the particles. The interaction is based on the socialization of the electrons of the lattice, 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 a straight line is drawn from boron to astatine. Elements close in location to this line are most often of a boundary nature and exhibit a duality of properties (for example, germanium).
Metals mostly form basic compounds. The oxidation states of such substances usually do not exceed two. In a group, the metallicity increases, while in a period it decreases. For example, radioactive francium exhibits more basic properties than sodium, and inIn the halogen family, iodine even has a metallic sheen.
Otherwise, the situation is in the period - inert gases complete the sublevels, before 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 (accept electrons when bonds are formed).
Nonmetals
This type of atoms is included in the main classes of inorganic chemistry. Non-metals occupy the right side of the periodic table, showing typically acidic properties. Most often, these elements occur 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 above, these include hydrogen, fluorine, bromine, chlorine and iodine.
These 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, non-metals behave predominantly as acids. They are powerful oxidizing agents due to the possibility of adding an additional number of electrons to complete the level.
Complex substances in inorganics
In addition to substances that are represented by one group of atoms,a distinction is made between compounds comprising 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 binarity of bonds in molecules. Classes of inorganic compounds are also considered from the point of view of the bond formed between the atoms. It can be ionic, metallic, covalent (polar or non-polar), or mixed. Usually, such substances clearly show basic (in the presence of metal), amforteric (dual - especially characteristic of aluminum) or acidic (if there is an element with an oxidation state of +4 and higher) qualities.
Three-element associates
The topics of inorganic chemistry provide for the consideration of this type of amalgamation 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 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 ones 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 faster in solution.
Classes of inorganic chemistry
The vast majority of substances studied in the inorganic course can be considered by a simple classification depending on their composition andproperties. So, hydroxides, acids, oxides and s alts are distinguished. Consideration of their relationship is better to start with an acquaintance 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
Oxide is a compound of any chemical element with oxygen in the oxidation state equal to -2 (in peroxides -1, respectively). Bond formation occurs due to the recoil and attachment of electrons with the reduction of O2 (when oxygen is the most electronegative element).
Can exhibit both acidic, and amphoteric, and basic properties, depending on the second group of atoms. If it is a metal, in the oxide it does not exceed the oxidation state of +2, if it is a non-metal - from +4 and above. In samples with the dual nature of the parameters, the value +3.
Acids in inorganics
Acidic compounds have a medium reaction less than 7 due to the content of hydrogen cations, which can go into solution and subsequently be replaced by a metal ion. By classification, they are complex substances. Most acids can be obtained by diluting the corresponding oxides with water, for example, in the formation of sulfuric acid after hydration of SO3.
Basic Inorganic Chemistry
The properties of this type of compounds are due to the presence of the hydroxyl radical OH, which gives the reaction of the medium above 7. Soluble bases are calledalkalis, they are the strongest in this class of substances due to complete dissociation (decay into ions in a liquid). The OH group in the formation of s alts can be replaced by acidic residues.
Inorganic chemistry is a dual science that can describe substances from different perspectives. In the protolytic theory, bases are considered as hydrogen cation acceptors. This approach expands the concept of this class of substances, calling alkali any substance that can accept a proton.
S alts
This type of compounds is between bases and acids, as it is the product of their interaction. Thus, a metal ion (sometimes ammonium, phosphonium, or hydroxonium) usually acts as a cation, and an acid residue acts as an anionic substance. When a s alt is formed, hydrogen is replaced by another substance.
Depending on the ratio of the number of reagents and their strength in relation to each other, it is rational to consider several types of interaction products:
- basic s alts are obtained if the hydroxyl groups are not completely substituted (such substances have an alkaline reaction environment);
- acid s alts are formed in the opposite case - with a lack of a 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 reagents 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 involvesdivision of 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 s alts are distinguished:
- Double contains a single anion in the presence of two cations. Usually such substances are obtained by merging two s alts 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.
- Crystal hydrates - s alts, in the formula of which there is water in a crystallized state.
- Complexes are substances in which a cation, anion or both of them are presented in the form of clusters with a forming element. Such s alts can be obtained mainly from elements of subgroup B.
Other substances included in the inorganic chemistry workshop that can be classified as s alts or as separate chapters of knowledge include hydrides, nitrides, carbides and intermetallides (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 at school in this subject. The course of inorganic chemistry provides for the systematization of large amounts of information in accordance with an understandable and simple classification.
