Homologous series: n,iso & neo hydrocarbon-IUPAC

Homologous series

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Homologous Series

A homologous series can be defined as group of compounds in which the various members have similar structural features & similar chemical properties & the successive members differ in their molecular formula by ‘CH2’ . Individual member of series are called homologue.

Characteristics of Homologous Series –

1 ) All compounds in the series are composed of same elements and contain the same functional group.

2) All compounds in the series can be represented by one general formula .

Ex. Homologous series of alcohol-

General formula =

CH3-OH

CH3-CH2-OH

CH3-CH2-CH2-OH

CH3-CH2-CH2-CH2-OH

3) The molecular mass of every two adjacent members differ by 14 or CH2 .

4) All members of series have similar chemical properties because of the presence of same functional group.

5) The members of series show a gradual gradation in their physical properties like solubility, density, melting point & boiling points. The physical properties generally increases as the molecular mass increases.

Primary, Secondary, Tertiary & Quaternary Carbon atoms –

Primary Carbon atom-

A carbon atom attached to other C-atom or no other Carbon atom is called primary carbon or 1⁰ carbon.

Secondary Carbon atom-

A carbon atom attached to two other carbon atoms is called secondary carbon atom or 2⁰Carbon.

Tertiary Carbon atom –

A carbon atom attached to three other carbon atoms is termed as tertiary carbon or 3⁰Carbon.

Quaternary Carbon atom-

A carbon atom attached to four other carbon atoms is termed as quaternary carbon atom or 4⁰Carbon.

(The Hydrogen atoms attached to Primary , secondary & tertiary Carbon atom are correspondingly termed as primary, secondary & tertiary hydrogen atoms respectively)