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Isomers of pentane Chemistry Munali Boys High Schools. . Definitions. IsomerismThe occurrence of two or more compounds with the same molecular formula but different structural formula. Isomers are therefore compounds with the same molecular formula but with different structural formula. Isomerism exists in all homologous series including the alkane family.AlkanesOrganic compounds having single carbon-carbon bonds in their structures and also conform to the general formula CnH2n 2.
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1. Isomers of Alkanes Catherine Mwenya
10th April 2008
Grade 12
2. Isomers of pentaneChemistryMunali Boys High Schools
3. Definitions Isomerism
The occurrence of two or more compounds with the same molecular formula but different structural formula. Isomers are therefore compounds with the same molecular formula but with different structural formula. Isomerism exists in all homologous series including the alkane family.
Alkanes
Organic compounds having single carbon-carbon bonds in their structures and also conform to the general formula CnH2n+2
4. Characteristics Isomers have different physical properties but similar chemical properties because the belong to the same family
5. Rules for Naming Isomers Identify the longest continuous carbon chain and name it. This will be the isomers last name or suffix. Bear in mind the homologous series of the isomer you are trying to draw.
Identify the attached alkyl groups and their positions. This will give the isomers first name or prefix.
Number the longest continuous carbon chain in such a way that these attached groups are at the least numbered carbon atoms in the chain.
6. Rules for Naming Isomers, Cont. Name the isomer, starting with the position of the attached alkyl group e.g methyl, ethyl, etc.
Use di, tri etc. when you have more than one of the same alkyl attached.
Use commas between figures and hyphens between a figure and a letter.
7. Example Draw and name the isomers of Pentane Isomer 1 is n-pentane, the straight chain normal structure for pentane
8. Isomer 2 is 2-methylbutane, a branched chain with a carbon* atomjoined onto three other carbon atoms
9. Isomer 3 is 2,2-dimethylpropane, a branched chain with the central carbon* atomjoined onto four other carbon atoms.
Note that for all the isomers, each carbon atom has four bonds (valency 4),and each hydrogen atom has one bond (valency 1).
Valency is the combining power of an atom.
10. Exercise What is an isomer?
Why do isomers have different physical properties?
Draw and name the isomers of hexane
11. Answers Compounds with the same molecular formula but different structural formula
Because they have different structures
Normal hexane, 2-methylpentane, 2,3-dimethylbutane, 2,2-dimethylbutane