Properties of homologous series

The physical properties of various members of a homologous series change regularly with an increase in the molecular mass. Such a series of compounds is known as an homologous series. In first year organic chemistry, the first ten names of the homologous series are usually all that need to be memorized. Homologous series definition a homologous series is a group of organic chemical compounds, usually listed in order of increasing size, that have a similar structure and hence, also similar properties and whose structures differ only by the number of c h 2 units in the main carbon chain. The steps below will take you through the required procedures. So, if the functional group doesnt change, why are homologous series interesting. Sep 23, 2016 in this video lecture, physical properties meltingboiling points, solubility in polar and nonpolar solvents, electrical conductivity, viscousity, flamability etc are discussed in details for. Such series are most common among organic compounds, the structural. For example, methane, ethane, and propane are part of a homologous series. Understanding the structural properties of a homologous. Homologous series is defined as a systematic order of organic compounds having same functional group that can be represented by same general formula and prepared by same method. Characteristics of homologous series carbon compound youtube.

A homologous series of bisdiphenylphosphine oxides c 6 h 5 2 poch 2 n poc 6 h 5 2 with n 28. Aug 20, 2018 what is the homologous series of hydrocarbons what do you mean by homologous series. In the field of organic chemistry, a homologous series is a sequence of compounds with the same functional group and similar chemical properties in which the members of the series can be branched or unbranched. Another approach to the problem is to consider what happens to the properties of a related series of compounds of increasing chain length. Dec 02, 2018 characteristics of homologous series carbon compound myhometuition. The word series implies that the members can be arranged in a single file and uniquely identified by an integer parameter. For example, the oh group, when attached to a saturated carbon, makes the parent molecule an alcoho.

This article describes some of the homologous series in inorganic chemistry, as well. Most of the homologous series are abundant in organic chemistry, but it is not unique only to organic chemistry. In this series, a group of compounds share similar basic chemical makeup. The first four alkanes in the homologous series retain their original names. Organic compounds also have functional groups, which define the basic properties of the compound. Homologous series have the same general formula with the neighbouring members of the series differing by ch 2. This means that the compounds are identical with the exception of the number of ch2 units in the compound. A homologous series in organic chemistry is a group of organic compounds compounds that contain carbon c atoms that diverge from each other by one methylene ch 2 group. The number of carbons continuously bonded together is an important structural feature and is described using the homologous series. Homologous series of inorganic compounds include the phosphoric acids, the silicic acids, and the phosphonitrilic chlorides. Choose a functional group aldehyde, carboxylic acid, ketone, amine, or alcohol.

Jun 12, 2017 each homologous series has its own functional group. Homologous series a homologous series is a group of compounds with similar characteristics and the same general formula. Significance and properties of the homologous series gulpmatrix. Carbon chains of varying length have been observed in organic compounds having the same general formula. Methods of preparation generally all the members of a series can be prepared by using same method. For example, the carboncarbon double bond allows all members of the alkene homologous series to undergo addition. Homologous series organic compounds are grouped into different homologous series. Homologous series examples, answers, activities, experiment. Among the different homologous series, the a 2 q n.

Some examples of homologous series are shown in the following table. What are the characteristics of homologous series answers. Each homologous series has its own functional group. In chemistry, a homologous series is a series of organic compounds with a similar general formula, possessing similar chemical properties due to the presence of the same functional group, and. Oct 10, 2014 it describes what are called a homologous series, examples of these series, and properties of some of selected homologous series in detail. You can think of an homologous series as a family or group of compounds, whose chemical behaviour is very similar and whose physical properties show trends when ascending the. Smectic properties are therefore most likely to be observed in the long chain members of an homologous series of mesomorphic compounds. In this lab you will look at how the physical properties of organic compounds depend on the functional group, molecular size, and resulting intermolecular forces. Chemical properties all the members of a homologous series have same chemical properties due to same functional group. Changes in physical properties in homologous series. Homologous series is a series of compounds with similar chemical properties and same functional group differing from the successive member by ch 2. For each series, be it a homologous series of aldehydes, carboxylic organic acids, alcohols or other substances, their properties will largely be determined by the type of functional group and naturally change in series with an increase in the molecular weight of the substance. In organic chemistry, a homologous series is a series of compounds with the same functional group due to the presence of the same functional group, compounds within the same homologous series have similar chemical properties. Homologous series grade 11 science notes reference notes.

The difference between two consecutive members in their composition is ch 2 unit. A homologous series homos is greek for the same as can be defined as the group of compounds in which the various members have similar structural features and similar chemical properties and the successive members differ in their molecular formula by one methylene ch 2 group. What is the difference between functional group and. A common pattern of behavior is that the lower homologous are nematic, the middle members exhibit a smectic mesophase followed by a nematic and the long chain members are purely smectic. They differ in formula from one member to the next by one ch2 unit. What are the physical and chemical properties of homologous.

Each member of your lab group needs to choose a different functional group. Each homologous series must have the following four characteristics. Differ by ch 2 in molecular formulae from neighbouring compounds. Natures chemistry homologous series national 5 chemistry. Written by teachers for the cie igcse chemistry course.

The defining characteristic of a homologous series is a repeating unit. In the general formula of compounds of a homologous series, the symbol r. Hence, all members of a homologous series have very similar chemical properties. A series of a organic compound each containing a characteristic functional group and the successive members differ by from each other in molecular formula by ch2methylene group is called homologous series. Characteristics of homologous series carbon compound. These functional groups determine the chemical reactions that an organic molecule can undergo. Principle cetyl alcohol is as palmitic acid ester the major component of spermaceti. What is the homologous series of hydrocarbons what do you mean by homologous series. Within a given homologous series the chemical properties of the compounds are. Homologous series homologous series characteristics. The simplest precedent is the sequence of properties for the saturated paraffin hydrocarbons normal alkanes. Every member in the homologous series can be represented by a common formula. Homologous series are families of organic compounds.

Such organic compounds that vary from one another by a repeating unit and have the same. A group of organic compounds containing same functional group which can be represented by the same general formula and which have similar trends in their properties are called a homologous series. In chemistry, a homologous series is a series of organic compounds with a similar general formula, possessing similar chemical properties due to the presence of the same functional group, and shows a gradation in physical properties as a result of increase in molecular size. In the field of organic chemistry, a homologous series is a sequence of compounds with the same functional group and similar chemical properties in which the. Homologous series of alkanes, alkenes and alkynes with examples. Physical properties physical properties of the members of a homologous series vary with the increase in atomic weight. The physical properties of an homologous series show a trend as the series is ascended. Properties of homologous series definition, examples, diagrams.

This means that they have similar chemical properties to each other and they have trends in physical properties. A homologous series is a set of organic compounds with the same functional group that vary only by a ch2 group. A homologous series is a group or family of organic compounds that has certain characteristics. For example, the alkane group contains the ch2 repeating unit. The physical properties of the members change gradually as the number of carbon atoms per molecule increases.

Mesomorphic properties of an homologous series of thioalkyl. They show a steady change in physical properties from one member to the next. As the molecular mass increases in any homologous series, a gradation in physical properties is seen. This is because the melting points and boiling points increase with increasing molecular mass.

Two consecutive members of a homologous series differs each. Homologous series are groups, or families, of organic compounds that contain the same functional groupings and whose members differ by. Chemicals in the same homologous series will show a gradual variation in one property eg. Homologous series cie igcse chemistry revision notes. In the general formula of compounds of a homologous series, the symbol r is used to represent its functional group. Notes on functional group and homologous series grade 11. A homologous series is a family of hydrocarbons with similar chemical properties who share the same general formula. The alkanes are a homologous series of hydrocarbons. Detailed revision notes on the topic homologous series. In organic chemistry, a functional group is a specific arrangement of atoms that confers specific chemical properties to the rest of the molecule. Physical properties change in a homologous series but chemical properties remain almost the same because the functional group does not change. A homologous series is a family of organic compounds that. Variation of some physical properties in a homologous series of hydrocarbons are described below.

Homologous series a series of compounds with similar chemical properties, in which members differ from one another by the possession of an additional ch2 group, is called a homologous series. Other physical properties such as solubility in a particular solvent also show a similar gradation. However, the physical properties of homologues are different because of increased london. The members of a series have same functional group. Within a given homologous series the chemical properties of the compounds are essentially all alike, and the physical properties vary in a continuous and predictable manner. In this video lecture, physical properties meltingboiling points, solubility in polar and nonpolar solvents, electrical conductivity, viscousity, flamability etc are discussed in details for. The chemical properties of homologous series are similar because they have the same functional group. In the simplest approximation, the members of a homologous series are assumed to have essentially the same properties, except for the increases in boiling point and melting point as shown in figure 41 for alkanes. An homologous series is a group of compounds with similar structural features that can be represented by a general formula whose members differ by one ch 2 unit.

Characteristics of homologous series carbon compound myhometuition. This generally will be true, except when the number of carbons is small and when the hydrocarbon chain has polar substituents. A homologous series refers to a series of carbon compounds which have a different number of carbon atoms. For example, the boiling points of the alkanes increase down the series, so that the first four members are gases at room temperature and standard pressure. The chemical properties of the individual members of an homologous series are similar and they. A hydrocarbon homologous series is a series of hydrocarbons which.