Inorganic chemistry is part of general chemistry. She is studying the properties and behavior of inorganic compounds - their structure and ability to react with other substances. This direction examines all substances, with the exception of those that are built from carbon chains (the latter are the subject of study of organic chemistry).
Description
Chemistry is a complex science. Its division into categories is purely arbitrary. For example, inorganic and organic chemistry are bound by compounds called bio-inorganic. 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 interconnections with other sciences. General and inorganic chemistry encompasses simple and complex substances, the number of which is close to 400,000. The study of their properties often includes a wide range of methods of physical chemistry, since they can combine the properties characteristic of a science such as physics. Conductivity, magnetic and optical activity, the effect of catalysts, and other “physical” factors affect the quality of substances.
Inorganic compounds are generally classified according to their function:
- acids;
- grounds;
- oxides;
- salt.
Oxides are often divided into metals (basic oxides or basic anhydrides) and non-metallic oxides (acidic oxides or acid anhydrides).
Origin
The history of inorganic chemistry is divided into several periods. At the initial stage, knowledge was accumulated through random observation. 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. Especially the population suffered from smallpox and plague. Aesculapius suggested that diseases are caused by certain substances, and the fight against them should be carried out using other substances. This led to the beginning of the so-called medico-chemical period. At that time, chemistry became an independent science.
The formation of a new science
During the Renaissance, chemistry from a purely practical field of research began to “grow” with theoretical concepts. Scientists tried to explain the underlying processes that occur 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 causing the chemistry of inorganic compounds to be studied separately from organic.
Chemists later tried to explain the phenomenon of burning. The German scientist Georg Steel created the theory of phlogistons, according to which a burnt body rejects a non-gravitational particle of phlogiston. In 1756, Mikhail Lomonosov experimentally proved that the combustion of some metals is associated with particles of air (oxygen). Antoine Lavoisier also refuted the theory of phlogistons, becoming the founder of the modern theory of combustion. He also introduced the concept of “compound of chemical elements”.
Development
The next period begins with the work of John Dalton 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, valency, equivalent, and molecule. Thanks to the discovery of the periodic law and the creation of the periodic system, Dmitry Mendeleev proved that the atomic-molecular theory is connected 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. A study of Albrecht Kessel and Hilbert Lewis in 1916 solves the problem of the nature of chemical bonds. Based on the theory of heterogeneous equilibrium by Willard Gibbs and Henrik Roszeb, Nikolai Kurnakov in 1913 created one of the main methods of modern inorganic chemistry - physical and chemical analysis.
The basics of inorganic chemistry
Inorganic compounds in nature are found in the form of minerals. The soil may contain iron sulfide, such as pyrite, or calcium sulfate in the form of gypsum. Inorganic compounds are also found 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.
Salt
Many inorganic compounds are ionic compounds consisting of cations and anions. These are the so-called salts that are the subject of inorganic chemistry research. 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 the degree of oxidation 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 a high melting point. Inorganic salts are usually solid crystalline formations. Another important feature is their solubility in water and ease of crystallization. Some salts (e.g. NaCl) are highly soluble in water, while others (e.g. SiO2) are almost insoluble.
Metals and Alloys
Metals, such as iron, copper, bronze, brass, aluminum, are a group of chemical elements in the lower left part of the periodic table. This group includes 96 elements that are characterized by high thermal conductivity and electrical conductivity. They are widely used in metallurgy. Metals can be conditionally divided into ferrous and non-ferrous, heavy and light. By the way, the most used element is iron, it occupies 95% of world production among all types of metals.
Alloys are complex substances obtained by melting and mixing two or more metals in a liquid state. They consist of a base (dominant elements in a percentage ratio: iron, copper, aluminum, etc.) with small additives 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 divided into several groups:
- 6 elements are in the alkaline group (lithium, potassium, rubidium, sodium, France, 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, sea anemone, thorium, fermium, etc.);
- 7 - semimetals (arsenic, boron, antimony, germanium, etc.);
- 7 - light metals (aluminum, tin, bismuth, lead, etc.).
Non-metals
Non-metals can be both chemical elements and chemical compounds. In a free state, they form simple substances with non-metallic properties. In inorganic chemistry, 22 elements are distinguished. These are hydrogen, boron, carbon, nitrogen, oxygen, fluorine, silicon, phosphorus, sulfur, chlorine, arsenic, selenium, etc.
The most typical non-metals are halogens. In reaction with metals, they form compounds, the bond of which is mainly ionic, for example KCl or CaO. When interacting with each other, non-metals can form covalently bound compounds (Cl3N, ClF, CS2, etc.).
Bases and Acids
Bases are complex substances, the most important of which are water-soluble hydroxides. Upon dissolution, they dissociate with metal cations and hydroxide anions, and their pH is greater than 7. The bases can be considered chemically opposite to 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.