All the members of a homologous series have similar chemical properties due to similar functional groups. The number of carbons continuously bonded together is an important structural feature and is described using the homologous series. Variation of some physical properties in a homologous series of hydrocarbons are described below. The alkanes are a homologous series of hydrocarbons. Write down two characteristics of the compound of an.
They have numerous chemical properties in common however encompass different physical properties. These properties typically change gradually along the series, and the changes can often be explained by mere differences in molecular size and mass. 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. Natures chemistry homologous series national 5 chemistry.
If they contain different functional groups and belong to different homologous series they differ in both physical and chemical properties, example. Homologous series have the same general formula with the neighbouring members of the series differing by ch2. Within a given homologous series the chemical properties of the compounds. All the members of a homologous series have the same a. They show a steady change in physical properties from one member to the next. Notes on functional group and homologous series grade 11. The alcohols which only contain one hydroxyl group attached to a saturated carbon form a homologous series. A series of organic compounds that have the same general formula but differ from each other by a common structural unit. Homologous series are referenced frequently in organic chemistry, where compounds can differ by the length of their carbon chain. For example, the series of primary straightchained alcohols has a hydroxyl at the end of the carbon chain. Physical properties like atomic mass,melting and boiling point and molecular mass differ by ch2 units in a homologous series. Members of the homologous series can be prepared using the same method. How do physical properties change in a homologous series.
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. Jun 12, 2017 the order in the physical and chemical properties of organic molecules in a homologous series makes it easy to predict the properties and behaviour of unknown members of the series. 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. The order in the physical and chemical properties of organic molecules in a homologous series makes it easy to predict the properties and behaviour of unknown members of the series. Within a homolgous series the intermolecular forces are the same.
A group of organic compounds which can be represented by the same general formula with a same functional group and which show more or less similar trends in their properties is known as homologous series. With an increase in molar mass, there is a gradual change in physical properties. Homologous series and functional groups extramarks. Homologous series of alkanes, alkenes and alkynes with. Significance and properties of the homologous series gulpmatrix. They show graduation in physical properties such as melting point, boiling point, density or solubility. 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. This lesson covers the definition of a homologous series of molecules in organic.
Homologous series is a series of compounds with similar chemical properties and same functional group differing from the successive member by ch 2. The steps below will take you through the required procedures. Cbse class 10 science carbon and its compounds the family of organic compounds have same functional group, similar chemical properties and their successive member differ by a. 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 ch2 units in the main carbon chain. The defining characteristic of a homologous series is a repeating unit. Functional groups are the atoms or group of atoms that determine the characteristic properties of compounds. As all members of the same series have the same functional groups, then the chemical properties are similar. These compounds have similar chemical properties due to the addition of same kind of functional group throughout the chain. Jan 11, 2016 compounds within a homologous series typically have a fixed set of functional groups that gives them similar chemical and physical properties. They differ in formula from one member to the next by one ch2 unit. 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 and mass. A homologous series is a family of hydrocarbons with similar chemical properties who share the same general formula. This is due to the increased relative molecular mass, as each member of the series differs from the previous member by one ch 2 unit. Members have similar chemical properties because they have same.
This means that they have similar chemical properties to each other and they have trends in physical properties. General characteristics of members of homologous series definition members of the series can be represented by a general formula. Which statement about successive members of all homologous series is correct. A homologous series is a group of organic compounds that are arranged in order of increasing molecular weights, such that they differ from each other by a ch2 methylene group. Similar chemical properties but different physical properties that include solubility and density w. A member of a homologous series is known as a homologue. Oct 15, 2019 characteristics of a homologous series are. Significance and properties of the homologous series. Successive members differ from each other by c h 2. Chemical properties all the members of a homologous series have same chemical properties due to same functional group. Compounds within a homologous series typically have a fixed set of functional groups that gives them similar chemical and physical properties. The members of a particular homologous series have almost same chemical properties due to presence of same functional group. Find data for each member of your homologous series.
In first year organic chemistry, the first ten names of the homologous series are usually all that need to be memorized. What are the physical and chemical properties of homologous. In the field of organic chemistry, a homologous series is a series of compounds with the same functional group and similar chemical properties in which the members of the series can be branched or unbranched this can be the length of a carbon chain, for example in the straightchained alkanes paraffins. The difference between two consecutive members in their composition is ch 2 unit. Other physical properties such as solubility in a particular solvent also show a similar gradation. Aug 20, 2018 what is the homologous series of hydrocarbons what do you mean by homologous series. By studying the properties of a few members of a homologous series, it is possible to deduce the properties of the other members in the same series.
General characteristics of members of homologous series definition. The homologous series of straight chain alkanes can be represented by the general formula c n. Nov 12, 2016 homologous series definition is of a series of chemical compounds having the same functional group but differing in composition by a fixed group of atoms. Features include a general formula and neighbouring members differing by ch2, with similar chemical properties and with a gradation in physical properties. 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.
As the molecular mass increases in any homologous series, a gradation in physical properties is seen. Alkanes form a homologous series and so do alkenes. Homologous series grade 11 science notes reference notes. Methane, ethane, propane, butane and so on is a homologous series. Physical properties physical properties of the members of a homologous series vary with the increase in atomic weight. Carbon and its compounds class 10 science ncert exercise. Each member of a homologous series is called a homologue. All the compounds in this series have similar chemical properties but they differ in their physical properties. Apr 18, 2010 same functional group,thus have the similar chemical properties,share a general formula,increase in an mr of 14 increase by ch2,share a trend in physical properties e. For example, methane and ethane are homologues and belong to the same. Isomers belonging to the same homologous series may differ in. There is another classification based on homologous series.
Feb 17, 2017 isomers belonging to same homologous series have the same functional group just the spatial arrangement is different and hence the chemical properties are the same. Jan 16, 2018 cbse class 10 science carbon and its compounds the family of organic compounds have same functional group, similar chemical properties and their successive member differ by a ch2 group, is. Members of the same homologous series have a similar structure, a pattern to their physical properties, similar chemical properties and the same general formula. All the compounds in a homologous series have same functional group that is why they have same chemical properties. Homologous seriesfunctional groups and isomerism, chemistry. Properties of homologous series definition, examples. Methods of preparation generally all the members of a series can be prepared by using same method. Such organic compounds that vary from one another by a repeating unit and have the same. Choose a functional group aldehyde, carboxylic acid, ketone, amine, or alcohol.
Gce study buddy the best o level revision resource. 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. This means that the compounds are identical with the exception of the number of ch2 units in the compound. Properties of homologous series definition, examples, diagrams. The physical properties of the members change gradually as the number of carbon atoms per molecule increases. All the compounds within a homologous series have the same general molecular formula and the same functional group carboncarbon, hydroxyl, carboxyl. Why do these substance all belong to the same homologous. In organic chemistry, a homologous series is a series of compounds with the same functional group and similar chemical properties in which the members of the series differ by the number of repeating units they contain.
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. Compounds of homologous series differ by ch 2 from their consecutive members. They show graduation in physical properties such as melting point, boiling point, density or. Changes in physical properties in homologous series. Physical properties of homologous series 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. Carbon and its compounds ncert exercise solution part 2. Functional groups and homologous series earj ib chemistry. Similarly the series of alkene and alkynes also forms homologous series. However, the physical properties of homologues are different because of increased london.
Carbon chains of varying length have been observed in organic compounds having the same general formula. The chemical properties of homologous series are similar because they have the same functional group. A homologous series is a group of organic chemical compounds, usually listed in order. Homologous series organic compounds are grouped into different homologous series. They also have similar chemical properties and show a gradation in physical properties due to the increase in size and mass of the molecules. A homologous series is a group of chemicals which have similar chemical. Homologous series compounds that are in the same homologous series have the same general molecular formula and have the same functional groups. Homologous series of inorganic compounds include the phosphoric acids, the silicic acids, and the phosphonitrilic chlorides. Bonding in organic compounds organic chemistry ccea.
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 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. The physical properties of various members of a homologous series change regularly with an increase in the molecular mass. Homologous series of alkanes, alkenes and alkynes with examples. A homologous series is a group or family of organic compounds that has certain characteristics. Methods of preparation generally all the members of a series can be. Homologous series wikimili, the best wikipedia reader. A hydrocarbon homologous series is a series of hydrocarbons which. The compounds of a homologous series can be represented by the same general formula. Molecules which can contain one or more double or triple bonds. Members have similar chemical properties because they have same functional group. 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. Carbon and its compounds homologous series youtube.
Ethanol, propanol and butanol undergo oxidatoin produce carboxylic acids. Physical properties change regularly with increasing number of carbon atoms. A homologous series is a family of organic compounds that. For example, the alkane group contains the ch2 repeating unit. Organic compounds also have functional groups, which define the basic properties of the compound. Cbse ncert notes class 10 chemistry carbon and its compounds.
Homologous series homologous series characteristics. This will count as a lab grade a homologous series is a set of organic compounds with the same functional group that vary only by a ch2 group. All the compounds of a homologous series show similar chemical and physical properties. Homologues have similar chemical properties because the functional group of. This generally will be true, except when the number of carbons is small and when the hydrocarbon chain has polar substituents. Physical properties change in a homologous series but chemical properties remain almost the same because the functional group does not change. These differences can have an effect on the physical properties of the chemicals, such as boiling point. They demonstrate a stable transform in physical properties from one member to the next. The physical properties of an homologous series show a trend as the series is ascended. Why chemical properties remain same and physical properties. Differ by ch 2 in molecular formulae from neighbouring compounds. In chemistry, a homologous series is a series of compounds with a similar general formula, possessing similar chemical properties due to the presence of the same functional group. 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 are families of organic compounds.