Characteristics of Alkanes, Alkenes and Alkynes

Hydrocarbon concept


Organic Chemistry defines hydrocarbons as those compounds consisting only of carbon and hydrogen, which can be classified into aromatic hydrocarbons and aliphatic hydrocarbons.

In this sense, Aromatic Hydrocarbons, also called Areno1, are those conjugated cyclic organic compounds, which have greater stability, which – according to Organic Chemistry – is promoted by electronic relocation in links 2 .

For their part, Aliphatic Hydrocarbons are defined mainly as those organic compounds made up of hydrogen and carbon that do not have sufficient properties to be considered Aromatic Hydrocarbons. They include the Alkanes, Alkenes and Alkines, considering the aliphatic hydrocarbons the easiest alcains.

On this occasion we will make a synthesis of the concept, characteristics, properties and nomenclature of each of these organic compounds, so that the reader can quickly and practically clarify the differences between each of them. Then the qualities of each of these Hydrocarbons:

Alkanes: concept, properties and nomenclature

According to professionals in Chemistry, it is known as Alkane to saturated hydrocarbons, which respond to the linear chemical formula CnH2n+2, where N represents the total number of carbons presented by the specific compound.

They also have SP3 hybridization, that is, the carbon atom has six electrons, arranged as follows: the orbit 1s counts with two electrons, which can be written as 1s2; two more electrons in orbital 2S, which can be represented as 2s2; while the remaining electrons are located in the orbital 2p2.

Among the main properties of the Alkanes can be named the following:

  • The first four alcanos, i.e. those ranging from C1 to C4 correspond to gaseous elements.
  • Elements ranging from C5 to C15 correspond to elements in the liquid state.
  • Those corresponding to the compounds of C16 and above are in solid state.
  • Likewise the Alkanes are characterized by not being soluble in water.
  • They also own being combustible.

As for their nomenclature, the first four alkanes have their own names, which are correlative: methane (considered the simplest of alcains to contain only one carbon atom), ethane, propane and butane.

From C5 the names will be made up of the Latin particle indicating the number of Carbons: pentane (C5H12), hexane (C6H14), heptane (C7H16), Octane (C8H18), Nonano (C9H20), Dean (C10H22), etc.

Alkenes: concept, properties and nomenclature

Alkenes, meanwhile, correspond to those unsaturated hydrocarbons that have in their molecule one or more double carbon-carbon bonds. Likewise, Organic Chemistry defines the Alkenes as those Alcanos who have lost two hydrogen atoms, resulting in the double carbon-carbon bond, which distinguishes it.

They respond to the linear formula CnH2n where as with the Alcanos, N represents the number of carbons. Alquenos also have SP2 hybridization, that is, that the carbon atom has a combination of orbital S with 2P, from which three hybrid orbitals are obtained. Within its physical properties, you can find the following:

  • First, alquens – like the Alkanes – are insoluble in water.
  • However, there are other substances in which they can be dissolved. In this sense, alquens are soluble in substances such as ether, chloroform and benzene.
  • They also have the property to have less density in water.
  • As for its double carbon-carbon bond, it has the peculiarity of breaking easily.
  • In relation to its nomenclature, it uses the same technique of the Alcanos to form their name with the Latin particle that refers to the total number of Carbons, only that in the case of alquens the ending is joined –eno.

Renters: concept, properties and nomenclature

Lastly, alkyls constitute a type of aliphatic hydrocarbon, which is characterized by containing in its composition, between two carbon atoms, at least one triple carbon-carbon-carbon bond, which is usually expressed as follows: C-C . Likewise the alkyls are characterized by responding to the linear formula CnH2n-2.

Alkyls also have SP hybridization, meaning that within their carbon atom there is a combination between orbital S and P, which result in two linearly oriented hybrid orbitals.

Among the main properties of the Alquinos are the following:

  • First, it is a high-stability compound, which is a direct consequence of the high energy provided by the triple carbon bond (C-C) with which it has.
  • Like the Alkanes and Alkenes, Alkines are insoluble in Water.
  • However, alkyls are quite soluble in benzene, ligroin, ether, i.e. in usual organic solvents, characterized by their low polarity.
  • Alkines also have a lower density than water.

The first three Alkines, i.e. C1, C2 and C3 are in a gaseous state.

As for its nomenclature, as with the Alcanos and Alquenos, the Latin particle corresponding to the number of Carbons that the compound has is used, but instead of the termination – anus (of the alcs) or –eno (of the alquenos) the particupa –ino is used.

The simplest alkyl is ethyne, also called acetylene, which forms a highly flammable gas, which is characterized by no odor and a little lighter than air.

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Characteristics of Alkanes, Alkenes and Alkynes
Source: curiosities  
September 18, 2019


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