The carbon atom is tetravalent, that is, it has the capacity to make four covalent bonds, which can be single, double or triple. Furthermore, these bonds can occur with other carbon atoms or with atoms of other chemical elements. Thanks to this property, carbon has a unique capacity, which is to go on making these connections and forming chains, which can be short or long.
This set of carbons bonded together and of heteroatoms that constitute the "skeleton" of organic molecules is called carbon chains.
As carbon is capable of forming a very large number of compounds, these were classified according to some characteristics of its chains in order to facilitate their study and for us to better understand their properties.
The main classification of these compounds is:
1. Open or acyclic chains: Are those that have two free ends or more. The chain of atoms does not undergo any closure. See some examples:
H3Ç? CH2? CH2? CH3 H3Ç? CH? CH? CH3 H3Ç? CH? CH3
?
CH3
2. Closed chains: They are those that do not have any free ends, as the atoms link together to form a ring or cycle. Examples:
Examples of closed carbon chains
Observation: Open and closed chains that do not have an aromatic ring (first structure of the bottom row in the image above) are also called alicyclics.
3. Mixed chains: They are those that have at least one free end and a cycle, that is, they have at least one open and one closed part. Examples:
Examples of mixed carbon chains
These three main groups are also classified according to other subdivisions, as shown in the diagram below:
Classification scheme of carbon chains
If you want to know more about each of these classifications, read the text Classification of Carbon Chains, in the section of Organic chemistry.
By Jennifer Fogaça
Graduated in Chemistry
Source: Brazil School - https://brasilescola.uol.com.br/o-que-e/quimica/o-que-e-classificacao-das-cadeias-carbonicas.htm
