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Classification of Hydrocarbons

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Hydrocarbons

The organic compounds containing carbon and hydrogen atoms are known as a hydrocarbon. For example- Methane (CH4), Ethane (C2H6), Hexane (C6H14), Benzene of aromatic hydrocarbon (C6H6) etc.

On the basis of structure, hydrocarbons can be broadly classified into two classes:

  1. Open chain hydrocarbons (Aliphatic compounds)
  2. Closed chain hydrocarbons (Cyclic compounds )Classification of Hydrocarbons

A) Open chain compounds -

The hydrocarbons, which contain atoms linked on the open chain are known as open-chain compounds. Example: n-pentane, iso-pentane, neo-pentane e.t.c.Examples

Neo-pentane (If central atom is attached to 4 carbon atoms).

Open chain compounds are further divided into-

  • Saturated hydrocarbons
  • Unsaturated hydrocarbons

Saturated hydrocarbons (alkane)

Those hydrocarbons, in which the carbon atoms are bonded to each other with a single covalent bond (-C-C-) are called saturated hydrocarbons. They are also known as alkanes. They follow general formula CnH2n+2(+ane suffix), where 'n' is any positive integer. For example-



If n=1, C1H2X1+2⇒ CH4 (Methane)

Propane
Propane

If n=2, C2H2X2+2⇒ C2H6 (Ethane)

They are also known as paraffin. Example- Propane.

Unsaturated hydrocarbons

Hydrocarbons, which the carbon atoms are bonded to each other with two (=C=C=), or three (-C≡C-) covalent bond and have the tendency to gain more hydrogen atoms are known as unsaturated hydrocarbons. They are two types:

  • Alkene: Hydrocarbons containing a double bond between carbon atoms are known as an alkene. They have the general formula of CnH2n (+ene suffix). For example- C2H24, C3H6.
  • Alkyne: Hydrocarbons containing a triple bond between carbon atoms are known as an alkyne. They have the general formula of CnH2n-2(+yne suffix). For example- C2H2, C3H4. Examples

B) Cyclic or Closed chain compounds

Those hydrocarbons, which contain the ring of carbon atoms are known as cyclic ring compounds. ExamplesExamples

They are further classified into Homocyclic and Heterocyclic compounds.

Homocyclic compounds: If the cyclic organic compounds are composed of carbon atoms, they are known as homocyclic compounds or homocyclic hydrocarbons.

Example: Cyclopentane, cyclohexane.

Examples

Homocyclic hydrocarbons are further divided into-

  • Aromatic hydrocarbons: Aromatic hydrocarbons are defined as "those cyclic hydrocarbons which have alternate C-C and C=C and are similar to the benzene ring in characters."
  • Alicyclic hydrocarbons: Those cyclic hydrocarbons, which have no alternate C-C and C=C and similar properties to aliphatic compounds in characters, are known as alicyclic compounds.

Examples of aromatic- Benzene, naphthalene etc.

Examples of alicyclic: Cyclohexane, cyclopentane.Aromatic and alicyclic compounds Aromatic and alicyclic compounds

Heterocyclic compounds: Those cyclic hydrocarbons, which are composed of carbon atoms as well as other elements like N, O, S etc. are known as heterocyclic compounds. For example-Examples

Reference:

Adhikari, Rameshwar; Khanal, Santosh; Subba , Bimala; Adhikari, Santosh; Khatiwada, Shankar Pd. Universal Chemistry XI. First. Vol. 1st. Kathmandu: Oasis Publication, 2069.

Chaudhary, Ganga Ram; Karna, Shila Kant Lal; Sharma, Kanchan; Singh, Sanjay; Gupta, Dipak Kumar. A Textbook of Higher Secondary Chemistry XI. Ed. 2nd. Kathmandu: Vidyarthi Pustak Bhandar, 2069 (2012).



  • The organic compounds containing carbon and hydrogen atoms are known as  hydrocarbons.
  • On the basis of structure, hydrocarbons can be broadly classified into two classes:

    1. Open chain hydrocarbons (Aliphatic compounds)
    2. Closed chain hydrocarbons (Cyclic compounds )
  • The hydrocarbons, which contain atoms linked on the open chain are known as open-chain compounds. Example: n-pentane, iso-pentane, neo-pentane etc.
  • Those hydrocarbons in which the carbon atoms are bonded to each other with a single covalent bond (-C-C-) are called saturated hydrocarbons.
  • Hydrocarbons, which the carbon atoms are bonded to each other with two (=C=C=), or three (-C≡C-) covalent bond and have the tendency to gain more hydrogen atoms are known as unsaturated hydrocarbons.
  • Those hydrocarbons, which contain the ring of carbon atoms are known as cyclic ring compounds.
  • If the cyclic organic compounds are composed of carbon atoms, they are known as homocyclic compounds or homocyclic hydrocarbons.
  • Those cyclic hydrocarbons, which are composed of carbon atoms as well as other elements like N,O,S etc. are known as heterocyclic compounds.
.

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