This document discusses isomers in organic chemistry. It defines isomers as different organic compounds that have the same molecular formula but different structures. Isomerism is only possible with hydrocarbons containing 4 or more carbon atoms, as these allow for multiple arrangements of carbon atoms. The number of possible isomers increases rapidly as the number of carbon atoms in an alkane molecule increases. To draw the structural formulas of all isomers of an alkane, one takes the carbon atoms in a straight chain to form the normal alkane, then draws different branched arrangements of the carbon atoms to find other isomers.

1. CHEMISTRY
NAME- ABHINAB
BORUAH
CLASS-10 ROLL NO-
12
SEC-A

2. TOPIC- ISOMERS

3. ISOMERS
In inorganic chemistry, a given molecular formula represents only one
compound. For example H2SO4 represents only one compound,sulphuric
acid. A given molecular formula can be represent two or more different
compounds. This is because in organic compounds, the same carbon
atoms can be arranged in several ways to give different structures and
hence different compounds. For example, in organic chemistry, the same
molecular formula C4H10 represents two compounds: normal butane and
iso-butane. The organic compounds having the same molecular formula
but different structures are known as isomers.

4. What is isomerism ?
The existence of two or more different organic compounds having the same
molecular formula but different structures is called isomerism. Isomerism is
possible only with hydrocarbons having 4 or more carbon atoms, because only
then we can have two or more different arrangements of carbon atoms. No
isomerism is possible in hydrocarbons containing 1,2,or 3 carbon atoms per
molecule because then only one arrangement of carbon atoms is possible. For
example, no isomerism is possible in methane,ethane,and propane because they
contain one, two or three carbon atoms respectively. Two isomers of the
compound butane possible. Three isomers of the compound pentane are
possible. And five isomers of the compound hexane are possible. As the number
of carbon atoms in an alkane molecules increases, the number of possible
isomers increases rapidly.

5. How to draw the structural formulae of all the isomers of an alkane?
In order to draw the structural formulae of all the isomers of an alkane, we should
take first all the carbon atoms present in alkane molecule in a straight chain and
attach hydrogen atoms to all the free valencies of carbon atoms. This will give us
the first isomer which is said to be normal- alkane .After this we have to work out
as many branched chain isomers of alkane as possible by drawing different
arrangements of its carbon atoms.

6. END OF PRESENTATION
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