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Definition of hydrocarbons


Hydrocarbons are organic chemical compounds consisting of carbon and hydrogen only, where carbon atoms are linked together to form the structure of the compound, and hydrogen atoms are attached to it in different forms, and it is the main component of oil and natural gas, used as fuel, lubricants, and raw materials for the production of plastics, fibers, and rubber solvents, explosives, and industrial chemicals; Hydrocarbons are also found in trees and plants in the form of pigments called carotenes, which are found in carrots and green leaves. 

Hydrocarbons are the simplest organic compounds, and although these compounds are composed of only two types of atoms, there are various groups of them; Because it consists of different lengths of chains, branched chains, rings of carbon atoms, or a mixture of these structures, and it is found in many plants, animals, and the fossil fuels resulting from them, and some of them can be prepared in the laboratory. 

Definition of hydrocarbons
Definition of hydrocarbons

Types of hydrocarbons

Alchemists divided hydrocarbon compounds in the nineteenth century into two main types depending on their source and properties, and these types are:

  • Aliphatic hydrocarbons: They are derived from the chemical dissolution of fats or oils, and are divided into three main groups depending on the type of bonds they contain. These groups are:

  1. Alkanes.
  2. Alkenes.
  3. Alkynes.

  • Aromatic hydrocarbons: They are derived from the chemical dissolution of extracts of some types of aromatic plants. They are divided into two types: 
  1. Arenes aromatic hydrocarbons: These include a benzene ring as its main building unit.
  2. Non-halogenated aromatic hydrocarbons: These are those that lack a benzene ring as their building unit.

The terms used to denote types of hydrocarbons have continued to the present day, but the compounds that these names describe are now classified based on their composition rather than their origins as in the previous classification. It is worth noting that alkanes are called saturated hydrocarbons, while alkanes are called saturated hydrocarbons. Aromatic compounds, alkenes, and alkynes are called unsaturated hydrocarbons.

It is also common in hydrocarbons that a single molecule may combine the building blocks of two or more hydrocarbon families; For example, a molecule containing a triple bond between carbon atoms and a benzene ring exhibits some characteristic properties of alkynes and other properties related to aromatic hydrocarbons.

Aliphatic hydrocarbons

Aliphatic hydrocarbons are organic compounds that contain carbon and hydrogen-bonded together in straight, branched or non-aromatic rings. Although hydrogen atoms are the most commonly bonded to the carbon chain, oxygen, nitrogen, sulfur, and chlorine are. It is also one of the atoms that may be present in this type of compound.

Methane CH 4 is the simplest type of aliphatic hydrocarbon compound, and it is released as a gas from decomposing bodies, and from the intestines of many animals, examples of them are also: acetylene, propane, propane, ethylene, and polyethylene. ; Therefore, it is often used as a fuel. 


Alkanes contain only single bonds, and all molecular formulas in them follow the following general formula: C n H 2n + 2, This formula means that the number of hydrogen atoms in it is equal to twice the number of carbon atoms in addition to the number 2. 

Alkanes are used as clean fuels that burn to produce water and carbon dioxide. Methane, ethane, propane, and butane are the first four alkanes in the chain, which are gases, while the other alkanes that follow are in the liquid state. 

Cycloalkanes are a type of alkanes that includes a carbon ring and not a benzene ring, and it possesses one single bond, so it is saturated, and its properties are similar to cycloalkanes in their alkanes; Such as cyclopropane or cyclobutane, but they may have higher boiling or melting points compared to them.


Alkenes contain only one double bond between carbon atoms, and all molecular formulas in them follow the following general formula: C n H 2n and they are highly chemically reactive. Examples include ethane, ethylene, and propane.


It contains one triple bond between carbon atoms, and all the formulas of the molecules in it follow the following general formula: C n H 2n - 2, and it is highly chemically reactive, which includes the addition of hydrogen or halogens, examples of which are: propane. The physical properties of alkenes and alkynes are generally similar to those of alkanes, or cycloalkanes of equal numbers of carbon atoms, and alkynes usually have higher boiling points than alkanes or alkenes.

aromatic hydrocarbons

Aromatic (aromatic) hydrocarbons can be defined as stable, unsaturated cyclic compounds, consisting mainly of carbon and hydrogen atoms, and benzene (C 6 H 6 ) is the most famous of these compounds, and it is difficult to separate in chemical reactions, unlike aliphatic hydrocarbons, It usually includes one or two benzene rings.

The economic importance of hydrocarbons

It results from burning hydrocarbons in the presence of a sufficient amount of oxygen, carbon dioxide, water, and heat, and this is the main reason for their use as a fuel in the world; Hydrocarbons are the main source of energy around the world; They provide fuels that can be converted into energy through oil refining, which provides a wide range of derivatives that play an important role in the global economy; Which includes their importance in the manufacture of plastics, solvents, and lubricants.


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