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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". The concept of homologous series was proposed in 1843 by the French chemist Charles Gerhardt. [4] A homologation reaction is a chemical process that ...
Each homology class is an equivalence class over cycles and two cycles in the same homology class are said to be homologous. [6] A chain complex is said to be exact if the image of the (n+1)th map is always equal to the kernel of the nth map. The homology groups of X therefore measure "how far" the chain complex associated to X is from being ...
A homologous series is a group of compounds that differ by a constant unit, generally a methylene (−CH 2 −) group. The reactants undergo a homologation when the number of a repeated structural unit in the molecules is increased. The most common homologation reactions increase the number of methylene (−CH 2 −) units in saturated chain ...
Alkyl groups form homologous series. The simplest series have the general formula −C n H 2n+1. Alkyls include methyl, (−CH 3), ethyl (−C 2 H 5), propyl (−C 3 H 7), butyl (−C 4 H 9), pentyl (−C 5 H 11), and so on. Alkyl groups that contain one ring have the formula −C n H 2n−1, e.g. cyclopropyl and cyclohexyl.
Based on the definition of homology specified above this terminology is incorrect since sequence similarity is the observation, homology is the conclusion. [3] Sequences are either homologous or not. [3] This involves that the term "percent homology" is a misnomer. [4]
The connecting map takes a relative cycle, representing a homology class in (,), to its boundary (which is a cycle in A). [2] It follows that (,), where is a point in X, is the n-th reduced homology group of X.
A 3D model of ethyne (), the simplest alkyneIn organic chemistry, an alkyne is an unsaturated hydrocarbon containing at least one carbon—carbon triple bond. [1] The simplest acyclic alkynes with only one triple bond and no other functional groups form a homologous series with the general chemical formula C n H 2n−2.
The general structure of the class of molecules is some number of oxygen atoms single-bonded to each other in a chain. The oxygen atom at each end of this oxygen skeleton is attached to a hydrogen atom. Thus, these compounds form a homologous series with chemical formula H 2 O