What is Homologous and How to Identify It in an Organic Chemistry Lab

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About Homologous and How to Identify It in an Organic Chemistry Lab

what is homologous series

In organic chemistry, a homologous series is a sequence of compounds with the same functional group and similar properties. Depending on the structure, the members of the homologous series may be branched or unbranched, but share the same -CH2 ending. A sequence is called a “homologous” if the compounds in the series have similar chemical properties. This article will discuss what is homologous and explain how to identify it in an organic chemistry lab.

A homologous series is a group of compounds with a common basic chemical make-up, but differ in a particular property. For example, alkanes and alcohols are both homologous. The compounds in a homologous series have the same carbon chain, but differ in other aspects of their structure. This gradation can result in different properties for the constituents of the series. When comparing two organic compounds, a homologous sequence is important in determining which are more or less similar.

Homologous against. Heterologous

Both homologous as well as homologous can be described in descriptive terms, but they are two different terms. The term homologous is used to describe biological entities that have a similar or similar characteristic and heterologous refers to an entity with a similar feature, it can be used to refer to the characteristics of an entity that differ significantly from each other.

For instance an example, an example of a heterologous tumour is a tumor that contains cells or tissues that is distinct from the area in which the tumor is formed. On the other hand homologous tumors homologous tumour is a tumor comprised of tissue or cells that resemble the tissue that it is formed. (Ref. 1)

Homologous Examples

Homologous structures

Homologous bodies are body organs that share the same anatomical characteristics which suggests that they share a common ancestor or origin. They could have the same characteristics, but they may not have the same purpose. For instance the forelimbs of bats as well as humans are similar structures.

The bones that make up bat forelimbs have the same bones as the human forelimbs. This is a sign of that they are a common ancestral species. The image below it illustrates the anatomical characteristics of the various animal forelimbs. In addition, bats and humans share the same bone forelimb components.

Whales, cats, lizards and birds all have the same or similar bones of the forelimbs, including the ulna, radius, humerus carpal, and phalanges. But, the forelimbs of various animals serve a different principal role.

For example, bats use their forelimbs to glide. Birds also make use of them to fly. Lizards and cats use these for climbing and walking.

Whales use their arms to swim. Humans don’t have the wings membrane, and are bipedal, which means that their arms are able to perform a wide range of but the functions are limited, e.g. grasping, reaching or climbing, swimming and many more.

Homologous chromosomes

Homologous chromosomes are pairs of and chromosomes. The chromosomes that make up a pair have the identical loci, gene sequence and centromere locations. They also share the same length of chromosomes. However, they can differ in the alleles.

Human cells is an example, having 46 chromosomes inside the nucleus. The majority (23 chromosomes) originate from the mother, and the remaining part (23 chromosomes) is come from dad. After fertilization these chromosomes join to create a nucleus inside the zygote cell. It then develops and becomes the human form. Every human cell body will have both sets of chromosomes.

The 22 pairs comprise Autosomes as well as homologous. The last pair is one of the sex chromosomes. Two X chromosomes are homologous well , but two sexual chromosomes that are composed of two X and Y chromosomes will not be homologous, but heterologous. The following diagram shows an illustration.

Characteristics of characteristics

The two characteristics of a homologous series are similarity and resemblance. For example, a primary straight-chained alcohol and an alkane both have a hydroxyl group at the end of their carbon chain. Similarly, a series of carboxylic acids and alcohols has a hydration-free molecular formula. While homologous substances are grouped together by structural properties, they are not the same.

A homologous series is a group of compounds that share the same general formula, but differ in a single parameter. The properties of the compounds in the homologous series are similar, although the first member may be very different from the rest. The gradation in chemical properties between constituents in a homologous range is called ‘homologous’. The homologous series is an organic compound.

Homologous series

A homologous series is a group of organic compounds that have the same functional groups but differ in their chemical properties. The first member of a homologous group is homologous to the others. Its properties are similar, but the second has different chemical characteristics. They are both considered heterologous. The first member of the series has the same properties. The other two are related but have different functions. The third one is a derivative of the same compound.

In organic chemistry, a homologous series is a series of compounds that share the same chemical properties. The compounds in a homologous group have the same general formula, but differ in their physical properties. Moreover, they share the same functional group. In contrast, a heterologous series has no functional groups. Its atoms have identical structures. However, the carbons in a heterologous series differ in their number. alkane


An alkane is an organic compound with a homologous series. In the latter case, the molecule is an isomer. An isomer is the same chemical compound as a methyl ether. They have a common functional group. This means that they have the same chemical properties. If the first member of a series has different physical properties, it is an isomer. Its second member is an isomer.


An alkaline series is a homologous series in organic chemistry. Its constituents have the same chemical formula but are different in a few ways. For instance, two ethanes share the same general formula, but differ in their chemical properties. The main difference between the two compounds is the hydrogen atoms. In the alkaline series, the molecules of both are identical. This means that the two homologous molecules have the same functional groups.


In the organic world, homologous series are chemical compounds that have similar chemical properties, but differ only in one parameter. For example, a hydrocarbon homologous series is a series of molecules whose molecules share the same methylene group. The first member of a homologous-series differs only by its methylene group. Another type of ahomologous series is an aromatic compound.

In organic chemistry, the term homologous series describes a group of compounds that have similar chemical properties and structural characteristics. All members of a homologous series have the same functional group – CH 2. In organic chemistry, the name of a compound is an adjective. A verb is a synonym for ‘alcohol.’ In the chemical language, an alcohol has the same structure. Its structural and functional group are also similar.