Organic chemistry
Fig 14 Some examples of skeletal formulae
CH3CH2CH2CH3 butane
CH3CH(CH3)CH2CH3 2-methylbutane
CH3C(CH3)2CH(CH3)CH2CH3 2,2,3-trimethylpentane
H2C=CHCH2CH3 but-1-ene
CH3CH=CHCH3 Z-but-2-ene (cis)
CH3CH=CHCH3 E-but-2-ene (trans)
O OH
O H
CH3CH2OH ethanol
CH3CH2CHO propanal
(CH3)2CO propanone
C6H12 cyclohexane
C6H11CH3 methylcyclohexane
C6H10 cyclohexene O
C6H6 benzene
C6H5CH3 methylbenzene
C6H5COCH3 phenylethanone
Definition A functional group is an atom or group of atoms which, when present in different molecules, causes them to have similar chemical properties
The functional group is the reactive part of a molecule; the properties of the molecule are largely determined by the nature of the functional group. A family of molecules which all contain the same functional group, but an increasing number of carbon atoms, is called an homologous series, and can be represented by a general formula. The general formulae and functional groups for the homologous series of alkanes, alkenes and haloalkanes are shown in Table 1.
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