# Organic Chemistry |Structural Representation of Organic Compounds

HYDROCARBONS: -
Compounds made up of carbon and hydrogen are called as hydrocarbons.
ORGANIC COMPOUNDS
Organic compounds are those, which occur in living sources such as plants and animals. They all contain carbon. Common organic compounds are oils, wax, fats etc.
Compounds contain C, H and heteroatom's (O, N, CL etc.) are Organic compounds.
ORGANIC CHEMISTRY: -
The branch of chemistry which deals with the study of hydrocarbons and their derivatives
Important Properties of Carbon which is responsible for Organic compounds
Catenation –The unique self-linking property of carbon is known as catenation. It forms bonds with carbon atoms. This is the main reason of existence of such large number of compounds
Tetra-valency of carbon
The atomic number of Carbon is 6 and its electronic configuration is 2, 4 i.e.it has 4 valence electrons. So, carbon is always tetra-covalent. It forms 4 covalent
bonds with other atoms

## Structural Representation of Organic Compounds

Complete structure Formula
Complete structure formula is a modified form of Lewis dot structure where a two-electron pair covalent bond is represented by a dash. A single dash represents a single bond, double dash is used for double bond and a triple dash represents triple bond
Example
1. Ethane (C2 H6)

2. Ethyne (C2 H2)

3.Ethene (C2 H4)

Condensed formula
It is structural formula where we omit one or all the covalent bond dashes and represent the formula by indicating the number of identical groups attached to an atom by a subscript
CH3 – CH3
H2C = CH2
HC≡CH

Bond line Formula
Bond-line structural Formula of organic compounds is a representation where carbon and hydrogen atoms are not shown and the lines representing carbon-carbon bonds are drawn in a zigzag fashion. The only atoms specifically written are oxygen, chlorine, nitrogen etc. The terminals denote methyl (–CH3) groups (unless indicated otherwise by a functional group), while the line junctions denote carbon atoms bonded to appropriate number of hydrogen's required to satisfy the valency of the carbon atoms
Example
3-Methyl octane can be written as

For cyclic compounds

Hybridisation in Organic compounds

 Class Formula Hybridization Alkane Cn H2n +2 Sp3 Alkene Cn H2n Sp2 Alkyne Cn H2n-2 Sp

Solved Examples
1. Provide the hybridisation of carbon atoms in the below compounds
a. CH2 =CH- C N
b.CH3CH=CHCN
a. sp2, sp2, sp
b. sp3 , sp2 , sp2 , sp
2. Give the number of Sigma and pi bonds in the following molecules
a) $CH_3NO_2$
b)$HCONHCH_3$
a) 6 Sigma and 1 pi bond
b)8 Sigma and 1 pi bond
3. Which of the following compounds contain all the carbon atoms in the same hybridisation state?
(i) H—C ≡ C—C ≡ C—H
(ii) CH3—C ≡ C—CH3
(iii) CH2 = C = CH2
(iv) CH2 = CH—CH = CH2
(i) and (iv)