Homologous series

[1] Compounds within a homologous series typically have a fixed set of functional groups that gives them similar chemical and physical properties.

The name "homologous series" is also often used for any collection of compounds that have similar structures or include the same functional group, such as the general alkanes (straight and branched), the alkenes (olefins), the carbohydrates, etc.

However, if the members cannot be arranged in a linear order by a single parameter, the collection may be better called a "chemical family" or "class of homologous compounds" than a "series".

In that series, successive members differ in mass by an extra methylene bridge (-CH2- unit) inserted in the chain.

Titanium, vanadium, and molybdenum oxides all form homologous series (e.g. VnO2n − 1 for 2 < n < 10), called Magnéli phases,[9] as do the silanes, SinH2n + 2 (with n up to 8) that are analogous to the alkanes, CnH2n + 2.