Homologous Series

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A homologous series of alkanes.
Homologous series have the same general formula with the neighbouring members of the series differing by CH2.  The chemical properties between members of the same homologous series are similar, but the physical properties change gradually as the size of the compounds grow.

Trends in Boiling point of Homologous Series

Moving down a homologous series, the sizes of the compounds grow larger and larger. This increase in size causes the Vanderwaals forces to grow, thus bonding the molecules to each other more strongly. This thus strengthens the attraction between the molecules and causes the boiling points to become higher.

 Structural Vs. Empirical Formula

A structural formula is one that shows unambiguously how the atoms are arranged together by showing every atom and bond

An Empirical  formula can omit bonds between atoms and can show identical groups bracketed together

The use of R to represent an alkyl group and to represent the benzene ring can be used in condensed structural formulas.