Examples of homologous series include groups of compounds called the alkanes, cycloalkanes and alkenes. Homologues have similar chemical properties because the functional group of the molecule does not change. What is the homologous series of hydrocarbons what do you mean by homologous series. Feb 14, 2019 causes them to have similar chemical properties homologous series are families of organic compounds with the same functional group and same general formula. Why do alkanes in an homologous series have similar chemical. A series of compounds having similar structural formulae, same functional group and hence similar chemical properties are called homologous series of compounds.
Dec 03, 2019 homologous series are families of organic compounds with the same functional group and same general formula. Thus, the presence of the functional group or groups determines the chemical, properties of a homologous series. In chemistry, a homologous series is a group of compounds that share the same basic chemical makeup, but differ in the number of iterations of a certain aspect of their structure. Methods of preparation generally all the members of a series can be prepared by using same method. Within a given homologous series the chemical properties of the compounds are essentially all alike, and the physical properties vary in a continuous and. Homologous series homologous series characteristics. A homologue also spelled as homolog is a compound belonging to a series of compounds differing from each other by a repeating unit, such as a methylene bridge. This can be the length of a carbon chain, for example in the straightchained alkanes paraffins, or it could be the number of monomers in a homopolymer such as amylose. Jan 11, 2016 in chemistry, a homologous series is a series of compounds with the same general formula, usually varying by a single parametersuch as the length of a carbon chain. Homologous series 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. A series of compounds which all have the same general formula and functional group.
Homologous series of inorganic compounds include the phosphoric acids, the silicic acids, and the phosphonitrilic chlorides. 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. If the only difference between the molecules is the length of the chain, then that is the only difference that can. Isomers belonging to the same homologous series may differ in. Nov 18, 2016 alkanes in a homologous series have similar chemical properties because the molecules have the same sort of bonds in the same array. Therefore, compounds that share that same functional group will inherently share similar chemical properties. Homologous series is a series of compounds with similar chemical properties and same functional group differing from the successive member by ch 2. However, the physical properties of homologues are different because of increased london. Members of the homologous series can be prepared using the same method. Have similar chemical properties the general formula for the homologous series of alkenes is c n h 2n where n is the number of carbon atoms. Significance and properties of the homologous series. Why do members of the same homologous series show similar. 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.
Organic compounds belonging to the main class can be divided into different families, known as homologous series, on the basis of similarity in structure and chemical properties. 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. Changes in physical properties in homologous series. In chemistry, homology is the appearance of homologues. What happens to the carbon in the functional group of carboxylic acids. Homologues of a series show similar chemical properties, but the extent of the reactions vary with increasing relative molecular mass. A hydrocarbon homologous series is a series of hydrocarbons which. Chemical properties all the members of a homologous series have same chemical properties due to same functional group. The alkanes are a homologous series of aliphatic hydrocarbons. In some cases, you can substitute one alcohol for another or use a mixture of alcohols. The chemical properties of homologous series are similar because they have the same functional group. The alkanes the alkanes are the simplest homologous series of hydrocarbons. The two characteristics of homologous series are as follows. Carbon chains of varying length have been observed in organic compounds having the same general formula.
Ibsl chemistry topic 10 organic chemistry multiple choice. The members of a homologous series have similar chemical properties. The members of the homologous series consists of same general formula such as alkanes have general formula c n h. Give the formula and name of the member with two carbon atoms. The structures and chemistry of individual hydrocarbons depend in large part on the types of chemical bonds that link together the atoms of their constituent molecules.
Aug 20, 2018 what is the homologous series of hydrocarbons what do you mean by homologous series. A particular functional group will always undergo similar types of chemical reactions. A series of compounds of the same family, with the same. Why do homologous series differ by ch2, and why does this not. The increased amount of nonpolar interactions in the alcohols increases their affinity with nonpolar solvents. Homologous series grade 11 science notes reference notes. The difference between two consecutive members in their composition is ch 2 unit. A homologous series is a family of hydrocarbons with similar chemical properties who share the same general formula. Physical properties change in a homologous series but chemical properties remain almost the same because the functional group does not change. Isomers belonging to the same homologous series may differ.
Learn vocabulary, terms, and more with flashcards, games, and other study tools. They have similar chemical properties, showing regular trends in physical properties e. All homologues have similar methods of preparation. Ethanol, propanol and butanol undergo oxidatoin produce carboxylic acids. Alkanes in a homologous series have similar chemical properties because the molecules have the same sort of bonds in the same array. Homologous series are referenced frequently in organic chemistry, where compounds can differ by the length of their carbon chain. They also have similar chemical properties and show a gradation in physical properties due to the increase in size and mass of the molecules. Hydrocarbons are chain molecules of varying lengths made from hydrogen and carbon atoms only, joined together by covalent bonds. 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 and similar chemical properties in which each successive member differs by ch 2.
Other physical properties such as solubility in a particular solvent also show a similar gradation. On the second question, saying that chemical properties will not change is. 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 case of alkanes, there is no functional group but thats not necessary for a homologous series. Hybridization in carbon atoms a functional group is an atom, a radical group of atoms or a bond common to a homologous series, and which determines the main chemical properties of the series. A series of compounds which all have the same general formula and functional group are the chemical properties of homologous series the same or different. At the same time, the solubility of this homologous series of alcohols increases in nonpolar solvents like hexane and benzene. Each member of an homologous series is different in length to the next by ch 2. As the molecular mass increases in any homologous series, a gradation in physical properties is seen. State two other characteristics of an homologous series. The alcohols which only contain one hydroxyl group attached to a saturated carbon form a homologous series. Groups of 10 male and 10 female mice were injected ip 3 timeswk for 24 weeks for a total dose of 1. All compounds having the same carbon framework skeleton and the same functional group in their molecules possess similar properties. The first and simplest homologue of this series is.
Because alkenes are hydrocarbons with at least one carboncarbon double bond the alkene homologous series starts at ethene c 2 h 4. A homologous series is a family of similar compounds with similar chemical properties due to the presence of the same functional group. Ill just quickly reiterate that the idea of a homologous series is purely empirical. A homologous series is a set of organic compounds with the same functional group that vary only by a ch2 group. The series which consists of similar structures and similar chemical properties in which the successive compounds differs by a ch 2 group is termed as homologous series. Ib chemistry on homologous series and functional groups of. Significance and properties of the homologous series gulpmatrix. Compounds in each set have the same little group of atoms called the functional group definition. Which of the following pairs of compounds belongs to the same.
Functional groups and homologous series sneak peek. Homologous series are referenced frequently in organic chemistry, where compounds can. Organic compounds that are part of the same homologous series generally have similar chemical properties as each other, due to the presence of the same. Homologous series chemistry britannica encyclopedia britannica. Properties of homologous series definition, examples. This is because the melting points and boiling points increase with increasing molecular mass. Homologous series of alkanes, alkenes and alkynes with. 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 ch 2 units in the main carbon chain 1. Melting point and boiling point increases as you go down a series,viscocity. 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. Alcohol refers to any chemical having an oh functional group hydroxyl bound to a saturated carbon atom. Homologous series of alkanes, alkenes and alkynes with examples. Examples of functional groups, homologous series, general formula.
The chemical properties of the individual members of an homologous series are similar and they. A functional group is a set of atoms which dictate the chemical properties of that compound. 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 see relative molecular mass. All alcohols will be oxidised to aldehydes irrespective of the number of carbon at. Natures chemistry homologous series national 5 chemistry. Are the chemical properties of homologous series the same or different. The members of a particular homologous series have almost same chemical properties due to presence of same functional group. Familiar examples of physical properties include density, color, hardness, melting and boiling points, and electrical conductivity. Alkanes form a homologous series and so do alkenes. Ib chemistry on homologous series and functional groups of organic molecules. They show a gradual change in physical properties e. What are the physical and chemical properties of homologous. They are further divided into sets or groups having the same general formula and related structures and properties.
Choose a functional group aldehyde, carboxylic acid, ketone, amine, or alcohol. Which of the following pairs of compounds belongs to the. As all members of the same series have the same functional groups, then the chemical properties are similar. A physical property is a characteristic of matter that is not associated with a change in its chemical composition. Describe the concept of homologous series as a family of similar compounds with similar properties due to the presence of the same functional group. Such a group of organic compound is called a homologous series.
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. In chemistry, a homologous series is a series of organic compound s 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 see relative molecular mass. 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 see relative molecular mass. 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. For example, ethane has a higher boiling point than methane since it has more van. Oct 24, 2012 a homologous series is a series in which every compound has same general formula and have sam chemical properties followed by same functional groupif any. Series of compounds in which the same functional group substitutes for hydrogen in a carbon chain is called a homologous series. Remember, the functional group is just the area of.
Start studying an introduction to organic chemistry learn vocabulary, terms, and more with flashcards, games, and other study tools. Those data are not readily available, but a quick experiment will verify it. The characteristics that enable us to distinguish one substance from another are called properties. Members have similar chemical properties because they have same functional group. All the compounds within a homologous series have the same general molecular formula and the same functional group carboncarbon, hydroxyl, carboxyl, ester, etc. Why do alkanes in an homologous series have similar. However, each alcohol is a distinct molecule, with its own melting point, boiling point. Each member of your lab group needs to choose a different functional group. Describe the concept of homologous series as a family of. More than 98 percent of natural crude rubber is a hydrocarbon polymer, a chainlike molecule consisting of many units linked together. 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. Compounds that are in the same homologous series have the same general molecular formula and have the same functional groups.
Melting point and boiling point increases as you go down a series,viscocity increases,density increases,flamability decreases. A homologous series is a series in which every compound has same general formula and have sam chemical properties followed by same functional groupif any. 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. Differ by ch 2 in molecular formulae from neighbouring compounds. Find data for each member of your homologous series. Ibsl chemistry topic 10 organic chemistry multiple choice questions. 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. In the chemistry world, many organic compounds exist. An homologous series is a family of substances that have similar chemical properties react in the same way and physical properties that gradually change as the substances increase in length. Field of chemistry which studies carbonbased compounds. Homologous series have the same general formula with the neighbouring members of the series differing by ch 2. A homologous series is a group or family of organic compounds that has certain characteristics. Covalent bonds are formed when atoms share pair of electrons.
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