Classification of Organic Compounds
Organic compounds are hydrocarbons and its derivatives.
Due to the unique properties of organic compounds that carbon is not only linked with carbon but also with other elements like nitrogen, oxygen, sulphur etc to form a long chain or ring compounds.
Therefore, organic compounds are in millions. To study organic compounds easily, they are divided into different groups and sub-groups.
Classification of Organic Compounds on the basis of structure
Organic compounds are classified into two major groups:
1)Open chain compounds or Acyclic compounds
2)Closed chain compounds or Cyclic compounds
What are Open chain compounds or Alicyclic compounds?
Those organic compounds with an open chain of carbon atoms are called Open chain compounds, or acyclic compounds.
The open chain may be straight or branched.

Straight chain Compounds:
Those compounds which contain any number of carbon atoms joined one after the other in a chain or row are known as Straight chain Compounds.

Branched chain Compounds:
Those compounds which contain carbon atoms on the sides of the chain are known as branched chain Compounds.
Examples:

Which one of the following is an open chain compound:
a)

b)

Answer: (a) is an open chain compound.
What are closed chain compounds or cyclic compounds?
Those organic compounds with closed cycles or atoms rings are called closed chain compounds or cyclic compounds.

Types of Cyclic compounds:
Closed (Cyclic) Chain compounds are further divided into :
1)Homocyclic compounds
2)Heterocyclic compounds
Homocyclic compounds:
Those organic compounds containing a closed chain of carbon atoms are called homocyclic compounds.
Examples of homocyclic compounds:

Homocyclic compounds are also called carbocyclic compounds. These compounds are of two types :
Aromatic and non-aromatic(Alicyclic) compounds.
Non-aromatic(Alicyclic) compounds
In non-aromatic (Alicyclic) compounds all the members of the ring are carbon atoms and their properties are almost the same as that of open chain compounds.
Examples are:

Aromatic compounds
Those compounds which having an alternate single and double bond in a ring are called aromatic compounds.

Heterocyclic compounds:
Those organic compounds which contain at least one different( hetero ) atom in the ring of carbon atoms are called heterocyclic compounds.
The atom other than carbon may be sulfur, oxygen, nitrogen, etc. They are called hetro atoms or hetro elements.
Examples of heterocyclic compounds:

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