The study of such an interesting subject as chemistry should begin with the basics, namely the classification and nomenclature of chemical compounds. This will help you not to get lost in such a complex science and put all new knowledge in its place.
Briefly about the main things
The nomenclature of chemical compounds is a system that includes all the names of chemicals, their groups, classes and rules, with the help of which the word formation of their names takes place. When was it developed?
The first nomenclature of chem. compounds was developed in 1787 by the Commission of French chemists under the leadership of A. L. Lavoisier. Until that time, names were given to substances arbitrarily: according to some signs, according to the methods of obtaining, according to the name of the discoverer, and so on. Each substance could have several names, that is, synonyms. The Commission decided that any substance should have only one single name; the name of a complex substance may consist of two words indicating the typeand the gender of the connection, and should not contradict the language norms. This nomenclature of chemical compounds became a model for the creation at the beginning of the 19th century of nomenclatures of various nationalities, including Russian. This will be discussed further.
Types of nomenclature of chemical compounds
It seems that it is simply impossible to understand chemistry. But if you look at the two types of chemical nomenclature. connections, you can see that everything is not so complicated. What is this classification? Here are two types of chemical compound nomenclature:
- inorganic;
- organic.
What are they?
Simple substances
The chemical nomenclature of inorganic compounds is the formulas and names of substances. A chemical formula is an image of symbols and letters that reflects the composition of a substance using the Periodic system of Dmitry Ivanovich Mendeleev. The name is the image of the composition of a substance using a specific word or group of words. The construction of formulas is carried out according to the rules of the nomenclature of chemical compounds, and, using them, the designation is given.
The name of some elements is formed from the root of these names in Latin. For example:
- С - Carbon, lat. carboneum, root "carb". Examples of compounds: CaC - calcium carbide; CaCO3 - calcium carbonate.
- N - Nitrogen, lat. nitrogenium, root "nitr". Examples of compounds: NaNO3 - sodium nitrate; Ca3N2 - calcium nitride.
- H - Hydrogen, lat. hydrogenium,hydro root. Examples of compounds: NaOH - sodium hydroxide; NaH - sodium hydride.
- O - Oxygen, lat. oxygenium, root "ox". Examples of compounds: CaO - calcium oxide; NaOH - sodium hydroxide.
- Fe - Iron, lat. ferrum, root "ferr". Compound examples: K2FeO4 - potassium ferrate and so on.
Prefixes are used to describe the number of atoms in a compound. In the table, for examples, substances of both organic and inorganic chemistry are taken.
| Number of atoms | Prefix | Example |
| 1 | mono- | carbon monoxide - CO |
| 2 | di- | carbon dioxide - CO2 |
| 3 | three- | sodium triphosphate - Na5R3O10 |
| 4 | tetro- | sodium tetrahydroxoaluminate - Na[Al(OH)4] |
| 5 | penta- | pentanol - С5Н11OH |
| 6 | hexa- | hexane - C6H14 |
| 7 | hepta- | heptene - C7H14 |
| 8 | octa- | octine - C8H14 |
| 9 | nona- | nonane - C9H20 |
| 10 | deca- | Dean - C10H22 |
Organicsubstances
With compounds of organic chemistry, everything is not as simple as with inorganics. The fact is that the principles of the chemical nomenclature of organic compounds are based on three types of nomenclature at once. At first glance, this seems surprising and confusing. However, they are quite simple. Here are the types of chemical compound nomenclature:
- historical or trivial;
- systematic or international;
- rational.
Currently, they are used to give a name to a particular organic compound. Let's consider each of them and make sure that the nomenclature of the main classes of chemical compounds is not so complicated as it seems.
Trivial
This is the very first nomenclature that appeared at the beginning of the development of organic chemistry, when there was neither a classification of substances nor a theory of the structure of their compounds. Organic compounds were assigned random names according to the source of production. For example, malic acid, oxalic acid. Also, the distinguishing criteria by which the names were given were color, smell and chemical properties. However, the latter rarely served as a reason, because during this period of time relatively little information was known about the possibilities of the organic world. However, many names of this rather old and narrow nomenclature are often used to this day. For example: acetic acid, urea, indigo (purple crystals), toluene, alanine, butyric acid and many others.
Rational
This nomenclaturearose from the moment the classification and unified theory of the structure of organic compounds appeared. It has a national character. Organic compounds get their names from the type or class to which they belong, according to their chemical and physical characteristics (acetylenes, ketones, alcohols, ethylenes, aldehydes, and so on). At present, such a nomenclature is used only in cases where it gives a visual and more detailed idea of the compound in question. For example: methyl acetylene, dimethyl ketone, methyl alcohol, methylamine, chloroacetic acid and the like. Thus, from the name it immediately becomes clear what the organic compound consists of, but the exact location of the substituent groups cannot yet be determined.
International
Its full name is the systematic international nomenclature of chemical compounds IUPAC (IUPAC, International Union of Pure and Applied Chemistry, International Union of Pure and Applied Chemistry). It was developed and recommended by the IUPAC congresses in 1957 and 1965. The rules for international nomenclature, published in 1979, were collected in the Blue Book.
The foundation of the systematic nomenclature of chemical compounds is the modern theory of the structure and classification of organic substances. This system aims to solve the main problem of nomenclature: the name of all organic compounds must include the correct names of substituents (functions) and their support - hydrocarbonskeleton. It must be such that it can be used to determine the only correct structural formula.
The desire to create a unitary chemical nomenclature for organic compounds originated in the 80s of the XIX century. This happened after the creation by Alexander Mikhailovich Butlerov of the theory of chemical structure, in which there were four main provisions that tell about the order of atoms in a molecule, the phenomenon of isomerism, the relationship between the structure and properties of a substance, as well as the influence of atoms on each other. This event took place in 1892 at the Congress of Chemists in Geneva, which approved the rules for the nomenclature of organic compounds. These rules were included in the organics called the Geneva nomenclature. Based on it, the popular Beilstein reference book was created.
Naturally, over time, the amount of organic compounds grew. For this reason, the nomenclature became more complicated all the time, and new additions arose, which were announced and adopted at the next congress, held in 1930 in the city of Liege. Innovations were based on convenience and conciseness. And now the systematic international nomenclature has absorbed some of the provisions of both Geneva and Liege.
Thus, these three types of systematization are the basic principles of the chemical nomenclature of organic compounds.
Classification of simple compounds
Now it's time to get acquainted with the most interesting: the classification of both organic and inorganic substances.
Now the worldthousands of different inorganic compounds are known. It is almost impossible to know all their names, formulas and properties. Therefore, all substances of inorganic chemistry are divided into classes that group all compounds according to a similar structure and properties. This classification is shown in the table below.
| Inorganic substances | |
| Simple | Metal (metals) |
| Non-metallic (non-metals) | |
| Amphoteric (amphigens) | |
| Noble gases (aerogens) | |
| Complex | Oxides |
| Hydroxides (bases) | |
| S alts | |
| Binary Compounds | |
| Acids | |
For the first division, we used how many elements a substance consists of. If from atoms of one element, then it is simple, and if from two or more - complex.
Let's consider each class of simple substances:
- Metals are the elements located in the first, second, third groups (except for boron) of the periodic table of D. I. Mendeleev, as well as elements of decades, lantonoids and octinoids. All metals have common physical (ductility, thermal and electrical conductivity, metallic luster) and chemical (reducing, interaction with water, acid, and so on) properties.
- Non-metals include all elements of the eighth, seventh, sixth (except polonium) groups, as well as arsenic, phosphorus, carbon (from the fifth group), silicon, carbon (from the fourth group) and boron (from the third).
- AmphotericCompounds are those compounds that can exhibit the properties of both non-metals and metals. For example, aluminum, zinc, beryllium and so on.
- Noble (inert) gases include elements of the eighth group: radon, xeon, krypton, argon, neon, helium. Their common property is low activity.
Since all simple substances are composed of atoms of the same element of the Periodic Table, their names usually coincide with the names of these chemical elements of the table.
To distinguish between the concepts of "chemical element" and "simple substance", despite the similarity of names, you need to understand the following: with the help of the first, a complex substance is formed, it binds to the atoms of other elements, it cannot be considered separately substances. The second concept lets us know that this substance has its own properties, without being associated with others. For example, there is oxygen that is part of the water, and there is oxygen that we breathe. In the first case, the element as part of the whole is water, and in the second case, as a substance in itself, which the organism of living beings breathes.
Now consider each class of complex substances:
- Oxides are a complex substance consisting of two elements, one of which is oxygen. Oxides are: basic (when dissolved in water, they form into bases), amphoteric (formed with the help of amphoteric metals), acidic (formed by non-metals in oxidation states from +4 to +7), double (formed with the participation of metals in differentoxidizing degrees) and non-s alt-forming (for example, NO, CO, N2O and others).
- Hydroxides include substances that have in their composition a group - OH (hydroxyl group). They are: basic, amphoteric and acidic.
- S alts are called such complex compounds, which include a metal cation and an anion of an acid residue. S alts are: medium (metal cation + acid residue anion); acidic (metal cation + unsubstituted hydrogen atom(s) + acid residue); basic (metal cation + acid residue + hydroxyl group); double (two metal cations + acid residue); mixed (metal cation + two acid residues).
- A binary compound is a two-element compound or a multi-element compound, including no more than one cation, or anion, or a complex cation, or anion. For example, KF, CCl4, NH3 and so on.
- Acids include such complex substances whose cations are exclusively hydrogen ions. Their negative anions are called acid residues. These complex compounds can be oxygenated or anoxic, monobasic or dibasic (depending on the number of hydrogen atoms), strong or weak.
Classification of organic compounds
As you know, any classification is based on certain characteristics. The modern classification of organic compounds is based on two most important features:
- structure of the carbon skeleton;
- presence of functional groups in the molecule.
A functional group is those atoms or a group of atoms on which the properties of substances depend. They determine which class a particular compound belongs to.
| Hydrocarbons | ||
| Acyclic | Limit | |
| Unlimited | Ethylene | |
| Acetylene | ||
| Diene | ||
| Cyclic | Cycloalkanes | |
| Aromatic | ||
- alcohols (-OH);
- aldehydes (-COH);
- carboxylic acids (-COOH);
- amines (-NH2).
For the concept of the first division of hydrocarbons into cyclic and acyclic classes, it is necessary to get acquainted with the types of carbon chains:
- Linear (carbons are arranged along a straight line).
- Branched (one of the carbons of the chain has a bond with the other three carbons, that is, a branch is formed).
- Closed (carbon atoms form a ring or cycle).
Those carbons that have cycles in their structure are called cyclic, and the rest are called acyclic.
A brief description of each class of organic compounds
- Saturated hydrocarbons (alkanes) are not capable of adding hydrogen and any other elements. Their general formula is C H2n+2. The simplest representative of alkanes is methane (CH4). All subsequent compounds of this class are similar to methane in their structure andproperties, but differ from it in composition by one or more groups -CH2-. Such a series of compounds that obey this pattern is called homologous. Alkanes are able to enter into substitution, combustion, decomposition and isomerization reactions (transformation into branched carbons).
- Cycloalkanes are similar to alkanes, but have a cyclic structure. Their formula is C H2n. They can participate in addition reactions (for example, hydrogen, becoming alkanes), substitution and dehydrogenation (hydrogen abstraction).
- Unsaturated hydrocarbons of the ethylene series (alkenes) include hydrocarbons with the general formula C H2n. The simplest representative is ethylene - C2H4. They have one double bond in their structure. Substances of this class are involved in the reactions of addition, combustion, oxidation, polymerization (the process of combining small identical molecules into larger ones).
- Diene (alkadienes) hydrocarbons have the formula C H2n-2. They already have two double bonds and are able to enter into addition and polymerization reactions.
- Acetylene (alkynes) differ from other classes in having one triple bond. Their general formula is C H2n-2. The simplest representative - acetylene - C2H2. Enter into addition, oxidation and polymerization reactions.
- Aromatic hydrocarbons (arenes) are so named because some of them have a pleasant smell. They have a cyclic structure. Their general formula is CH2n-6. The simplest representative is benzene - C6H6. They can undergo halogenation reactions (replacement of hydrogen atoms by halogen atoms), nitration, addition and oxidation.
