Hydrocarbons are organic compounds that contain only carbon and hydrogen atoms. Hydrocarbons are mainly classified based on the type of bonds present between carbon atoms. If the carbon atoms are connected only by single bonds, the hydrocarbons are called saturated hydrocarbons. If the carbon atoms contain double or triple bonds, they are known as unsaturated hydrocarbons.
Hydrocarbons
- They are considered the basic compounds of organic chemistry because many other organic substances are derived from them.
- Hydrocarbons are widely found in natural sources such as petroleum, natural gas, and coal, and they play an important role as fuels and industrial raw materials.
- Hydrocarbons can exist in different forms depending on how the carbon atoms are bonded with each other.
- They may contain single bonds, double bonds, or triple bonds between carbon atoms. Based on this bonding, hydrocarbons are classified into different types such as alkanes, alkenes, and alkynes.
Examples: Methane (CH4), Ethane(C2H6), Ethene(C2H4)
These compounds contain only carbon and hydrogen atoms, which makes them hydrocarbons.
Properties
Hydrocarbons show several important properties because they contain only carbon and hydrogen atoms. These properties are:
- Most hydrocarbons are nonpolar compounds because the difference in electronegativity between carbon and hydrogen is very small.
- Due to their nonpolar nature, hydrocarbons are generally insoluble in water but dissolve easily in organic solvents such as benzene, ether, or chloroform.
- Hydrocarbons are also combustible substances, which means they can burn in air or oxygen to produce carbon dioxide and water while releasing a large amount of heat energy.
- Lower hydrocarbons with a small number of carbon atoms are usually gases, while those with more carbon atoms may be liquids or solids.
Types of Hydrocarbon
Hydrocarbons can exist in different forms depending on the type of bonds present between the carbon atoms. The arrangement of these bonds plays an important role in determining the structure, properties, and chemical behaviour of hydrocarbons.
On the basis of the type of bonding between carbon atoms, hydrocarbons are mainly classified into two types:
1) Saturated Hydrocarbons
- Saturated hydrocarbons are hydrocarbons in which all the carbon atoms are connected by single covalent bonds (C–C).
- In these compounds, each carbon atom is bonded with the maximum possible number of hydrogen atoms, which means the carbon atoms are fully saturated with hydrogen.
- Because of this reason, they are called saturated hydrocarbons.
- Saturated hydrocarbons are also known as alkanes and they are among the simplest organic compounds.
- They occur naturally in sources such as natural gas and petroleum and are widely used as fuels.
The general formula of saturated hydrocarbons (alkanes) is: CnH2n+2
Examples: methane (CH₄), ethane (C₂H₆), propane (C₃H₈), and butane (C₄H₁₀).
They are further classified as:
Alkanes
- Alkanes are a group of saturated hydrocarbons in which all the carbon atoms are connected by single covalent bonds (C–C).
- They contain the maximum possible number of hydrogen atoms attached to the carbon atoms, which is why they are called saturated compounds.
- Alkanes are the simplest hydrocarbons and form an important homologous series in organic chemistry.
The general formula of alkanes is: CnH2n+2
- Each successive member in the alkane series differs from the previous one by a –CH₂ group, which is a characteristic feature of a homologous series.
2) Unsaturated Hydrocarbons
- Unsaturated hydrocarbons are hydrocarbons in which carbon atoms are connected by one or more multiple bonds, such as double bonds (C=C) or triple bonds (C≡C).
- Because these compounds do not contain the maximum possible number of hydrogen atoms attached to carbon atoms, they are called unsaturated hydrocarbons.
- The presence of multiple bonds makes unsaturated hydrocarbons more reactive than saturated hydrocarbons.
- These bonds can easily take part in chemical reactions such as addition reactions, where other atoms or groups of atoms can add across the multiple bond.
Examples: Ethene (C₂H₄), Propene (C₃H₆), Ethyne (C₂H₂).
Further classified based on the type of multiple bond present between the carbon atoms as:
a) Alkenes
- Alkenes are unsaturated hydrocarbons that contain at least one carbon–carbon double bond (C=C).
- Because of the presence of a double bond, alkenes are more reactive than saturated hydrocarbons.
The general formula of alkenes is
CnH2n
Examples: ethene (C2H4) and propene (C3H6).
b) Alkynes
- Alkynes are unsaturated hydrocarbons that contain at least one carbon–carbon triple bond (C≡C).
- These compounds also show high reactivity due to the presence of the triple bond.
The general formula of alkynes is
CnH2n-2
Examples: ethyne (C2H2) and propyne (C3H4).
| Saturated Hydrocarbons | Unsaturated Hydrocarbons |
|---|---|
| Carbon atoms are connected only by single bonds (C–C). | Carbon atoms contain double (C=C) or triple bonds (C≡C). |
| They contain the maximum number of hydrogen atoms. | They do not contain the maximum number of hydrogen atoms. |
| They are generally less reactive. | They are generally more reactive due to multiple bonds. |
| They mainly belong to the alkane series. | They mainly include alkenes and alkynes. |
| Example: Methane (CH₄), Ethane (C₂H₆) | Example: Ethene (C₂H₄), Ethyne (C₂H₂) |