Binary compounds are substances that are formed by two different chemical elements. This term is used to indicate the qualitative and quantitative composition of inorganic compounds.
Binary chemical compounds are considered an important object in the study of the nature of substances. When describing them, the following concepts are used: bond polarization, oxidation state, valency. These chemical terms make it possible to understand the essence of the formation of a chemical bond, the structural features of inorganic substances.
Consider the main classes of binary compounds, the features of their chemical structure and properties, some areas of their industrial application.
Oxides
This class of inorganic substances is the most common in nature. Among the known representatives of this group of compounds, we distinguish:
- silicon oxide (river sand);
- hydrogen oxide (water);
- carbon dioxide;
- clay (alumina);
- iron ore (iron oxides).
Such binary compounds are complex substances, in the composition of which oxygen is necessarily present, exhibiting an oxidation state of -2.
Aggregate state of oxides
Compounds of copper, calcium, iron are crystalline solids. The oxides of some nonmetals, for example, hexavalent sulfur, pentavalent phosphorus, and silicon, have the same state of aggregation. The liquid under normal conditions is water. The vast majority of non-metal oxygen compounds are gases.
Education Features
Many binary oxygen compounds are formed in nature. For example, when burning fuel, breathing, rotting organic substances, carbon dioxide is formed (carbon monoxide 4). In air, its volumetric content is about 0.03 percent.
Such binary compounds are products of the activity of volcanoes, as well as an integral part of mineral water. Carbon dioxide does not support combustion, therefore this chemical compound is used to extinguish fires.
Volatile hydrogen compounds
Such binary compounds are an important group of substances in which hydrogen is present. Among the representatives of industrial importance, we note methane, water, hydrogen sulfide, ammonia, as well as hydrogen halides.
Some volatile hydrogen compounds are present in soil waters, living organisms, so we can talk about their geochemical and biochemical role.
To make binary compounds of this kind, hydrogen having valency is put first. The second element is non-metal having a negative oxidation state.
For the arrangement of indices in a binary connection between valencies, the least common multiple is determined. The number of atoms of each element is determined by dividing it by the valency of each element that is part of the compound.
Hydrogen chloride
Consider the formulas of binary compounds: hydrogen chloride and ammonia. It is these substances that are relevant to the modern chemical industry. HCl under normal conditions is a gaseous compound, readily soluble in water. After the dissolution of gaseous hydrogen chloride, hydrochloric acid is formed, which is used in many chemical processes and production chains.
This binary compound is found in the gastric juice of humans and animals, and is a barrier to pathogenic microbes that enter the stomach with food.
Among the main areas of application of hydrochloric acid, we single out the production of chlorides, the synthesis of chlorine-containing products, the etching of metals, the cleaning of pipes from oxides and carbonates, and the leather industry.
Ammonia having the formula NH 3 is a colorless gas with a specific pungent odor. Its unlimited solubility in water allows you to get ammonia, which is in demand in medicine. In nature, this binary compound is formed during the decay of organic products, in which nitrogen is present.
Oxide classification
An oxygen-containing binary compound of a metal having a valency of 1 or 2 is the main oxide. For example, this group includes oxides of alkali and alkaline earth metals.
The oxides of non-metals, as well as metals with a valency greater than 4, are acidic compounds.
Representatives of this class are divided into salt-forming and non-salt-forming groups depending on the chemical properties.
Among typical representatives of the second group, we mention carbon monoxide (CO), nitric oxide 1 (NO).
Formation of systematic names of compounds
Among the tasks offered to graduates who pass the state chemistry exam are the following: “Compose the molecular formulas of possible binary oxygen compounds of sulfur (nitrogen, phosphorus).” In order to cope with the task, it is necessary to have an idea not only about the algorithm, but also about the features of the nomenclature of this class of inorganic substances.
When forming the name of the binary compound, initially indicate the element that is located on the right in the formula, adding the suffix "id". Next, indicate the name of the first element. For covalent compounds, prefixes are added by which a quantitative ratio between the constituents of the binary compound can be established.
For example, SO 3 - sulfur trioxide, N 2 O 4 - diazotetroxide, I 2 CL 6 - hexachloride diode.
If a chemical element is present in the binary compound that can exhibit different degrees of oxidation, the oxidation state is indicated in parentheses after the name of the compound.
For example, two iron compounds differ in name: FeCL 3 - iron oxide (3), FeCL 2 - iron oxide (2).
For hydrides, in particular non-metallic elements, use trivial names. So, H 2 O is water, HCL is hydrogen chloride, HI is hydrogen iodide, and HF is hydrofluoric acid.
Cations
The positive ions of those elements that are capable of forming only one stable ion are given the same names as the symbols themselves. These include all representatives of the first and second groups of the periodic table.
For example, sodium and magnesium cations have the form: Na + , Mg 2+ . Transition elements are capable of forming several types of cations, therefore, the valency shown in each individual case must be indicated in the name.
Anions
For simple (monatomic) and complex (polyatomic) anions, the suffix -id is used.
A common oxoanion of a particular element is the suffix -am. For the oxoanion of an element in a formula with a lower oxidation state, the suffix –it is used. For the minimum oxidation state, the prefix hypo is used, and for the maximum value, per-. For example, the O 2– ion is an oxide ion, and O - a peroxide.
There are various trivial names for hydrides. For example, N 2 H 4 is called hydrazine, and PH 3 is called phosphine.
Sulfur-containing oxoanions have the following names:
- SO 4 2- - sulfate;
- S 2 O 3 2- - thiosulfate;
- NCS - - thiocyanate.
Salt
In many final chemistry tests, the following task is proposed: "Write the formulas of binary metal compounds." If the composition of such compounds contains anions of chlorine, bromine, iodine, such compounds are called halides, belong to the class of salts. In the preparation of the formulas of these binary compounds, metal is put first, then the corresponding halide ion.
To determine the number of atoms of each element, the smallest multiple between the valencies is found; upon division, indices are obtained.
Such compounds have a high melting and boiling point, good solubility in water, and under normal conditions they are solids. For example, sodium and potassium chlorides are part of seawater.
People have been using common salt since ancient times. Currently, the use of this binary compound is not limited to food consumption. During the electrolysis of an aqueous solution of sodium chloride, sodium metal and gaseous chlorine are obtained. These products are used in various manufacturing processes, for example, to produce sodium hydroxide, hydrogen chloride.
The meaning of binary compounds
This group includes a huge amount of substances, so we can confidently talk about the scale of their use in various fields of human activity. Ammonia in the chemical industry is used as a precursor in the manufacture of nitric acid, the production of mineral fertilizers. It is this binary compound that is used in fine organic synthesis, and has long been used in refrigeration units.
Due to the unique hardness of tungsten carbide, this compound has found application in the manufacture of a diverse cutting tool. The chemical inertness of this binary compound allows its use in aggressive environments: laboratory equipment, furnaces.
"Laughing gas" (nitric oxide 1) in a mixture with oxygen is used in medicine for general anesthesia.
All binary compounds have a covalent or ionic character of a chemical bond, a molecular, ionic or atomic crystal lattice.
Conclusion
When drawing up formulas for binary compounds, a certain algorithm of actions must be observed. First, an element is recorded that exhibits a positive oxidation state (has a lower value of electrical negativity). When determining the oxidation state of the second element, the number of the group in which it is located is subtracted from the eight. If the numbers obtained differ from each other, the least common multiple is determined, then the indices are calculated.
In addition to oxides, carbides, silicides, peroxides, hydrides are assigned to these compounds. Aluminum and calcium carbides are used for laboratory production of methane and acetylene, peroxides are used in the chemical industry as strong oxidizing agents.
A halide such as hydrogen fluoride (hydrofluoric acid) is used in soldering electrical engineering. Among the most important binary compounds, without which it is difficult to imagine the existence of living organisms, water leads. The structural features of this inorganic compound are studied in detail in a school chemistry course. It is on her example that the guys get ideas about the sequence of actions in compiling formulas of binary compounds.
In conclusion, we note that it is difficult to find such a sphere of modern industry, the field of human life, wherever various binary compounds are used.