1. Isomers are molecules that have the same molecular formula, but have a different arrangement of the atoms in space. e.g. 1-pentene and 2-pentene are isomers CH3CH2CH2CH=CH2(1-Pentene) & CH3CH2CH=CHCH3(2-Pentene)
ISOMERISM OF ALKANES - definition
Alkanes are straight chain hydrocarbons in which structural isomerism is present.The alkanes containing four or more carbon atoms can be represented by more than one structural formula. e.g. Butane (C4H10) can be represented by following two structural formulae, a straight chain CH3−CH2−CH2−CH3 and another branched chain CH3−CH(CH3)−CH3.
Nomenclature of branched chain alkanes - definition
1. The longest carbon chain in the molecule is identified 2. The numbering is done in such a way that the branched carbon atoms get the lowest possible numbers 3. The names of alkyl group attached as a branch are then prefixed to the name of the parent alkane and position of the substituents is indicated by the appropriate numbers 4. Numbers are separated by commas 5. Lower numbers is given to the one coming first in the alphabetical listing