Two important homologous series to know in igcse chemistry are alkanes and alkenes. Homologous series are chemically similar or chemically the same or react in the same way. However, if the members cannot be arranged in a linear order by a single parameter, the collection. Alkenes are hydrocarbons that have a carboncarbon double bond. All the families of organic compounds exist as a homologous series a series having a difference of ch2 unit between two consecutive members the main homologous series es are alkanes, alkenes. Alkanes form a homologous series and so do alkenes. The data of table 101 allow comparison of the boiling points, melting points, and densities of several alkenes with the corresponding alkanes that have the same carbon skeleton. This means that they have similar chemical properties to each other and they have trends in physical. Consider the distinguishing features of each class, the type of hybridization, the characteristic properties.
This sounds a bit off considering that alkanes homologous series does not contain any functional group. Alkanes, alkenes, alcohols, carboxylic acids and esters belong to different homologous series. Alkenes contain a double bond between carbons, and alkynes contain a triple bond between carbons. Volatility refers to the ability of a liquid to change into vapour state. Ppt alkanes and alkenes powerpoint presentation free. In the field of organic chemistry, a homologous series is a sequence of compounds with the. Shaltiels homologous series method of synthesizing hydrocarboncoated agaroses.
Chem alkanes and alkenes chemistry organic chemistry. For organic substances combined in a group, regular changes in chemical and physical properties are observed, and all of them correlate with changes in molecular weight. Furthermore, from methane to ethane and from ethane to propane i. Homologous series of alkanes, alkenes and alkynes with examples. How to grow loofa luffa for sponges late bloomer episode 15 duration. Both alkenes and alkynes are saturated hydrocarbons. A fact sheet that was used for an assignment looking at the differences in physical properties of different homologous series related to intermolecular forces. Files are available under licenses specified on their description page. Alkynes are hydrocarbons that have a carboncarbon triple bond ch3c.
The boiling point increases down a homologous series. Jan 29, 2016 they are grouped into families called homologous series. The first four members of the homologous series of the alkenes are. The series like methanol, ethanol, propanol, butanol and so on is also a. A homologous series in organic chemistry is a group of organic compounds compounds that contain c atoms that differ from each other by one methylene ch 2 group. Gives example of homologous series alkanes, alkenes and alcohols and physical properties. In sufficient oxygen, the products will be carbon dioxide and water. Since alkenes contain double carbon bonds, they are unsaturated hydrocarbons. Homologous series of alkanes, alkenes and alkynes with. The general formula for alkenes are cnh2n, where n is the number of carbons in the alkene. For organic substances combined in a group, there are regular changes in chemical and physical properties, and all of them correlate with the change in molecular weight. This page was last edited on 1 december 2015, at 18.
The simplest alkene is ethene c 2 h 4 because methene ch 2 cannot exist. Ch3chch2 c3h6 and ch3chchch3 c4h8 are examples of alkenes. In organic chemistry, many classes are distinguishedcxhy. The inherent ability of hydrocarbons to bond to themselves is known as catenation, and allows hydrocarbon to form more complex molecules, such as cyclohexane and benzene. Made for lower ability students but can be easily adapted for higher ability students. Alkenes are more reactive than alkanes, due to the presence of the electron rich cc. Name of an alkene ends with ene each member of the alkene homologous series differs from the next by a ch2 unit general formula of cnh2n note. How are alkanes, alkenes, and alkynes homologous series. Alkanes, also known as paraffins, are the simplest of organic compounds. Alkane a homologous series of hydrocarbons that contains only single carbon bonds. After these the names are formed by adding the ending ane to the greek word for the number of carbon atoms in the molecule. Hydrocarbons are chain molecules of varying lengths made from hydrogen and carbon atoms only, joined together by covalent bonds. But, alkanes are hydrocarbons, meaning that there are only hydrogen and carbon atoms.
Describe the concept of homologous series of alkanes and alkenes as families of compounds with similar properties. A homologous series is a group or family of organic compounds that has certain characteristics. There is also a gradual change in physical properties as the relative molecular mass increases. The alkanes, alkenes and cycloalkanes are examples of homologous series. This means that they have similar chemical properties to each other and they have trends in physical properties. There is a certain similarity between the representatives of the given homologous series and alkenes. Learn vocabulary, terms, and more with flashcards, games, and other study tools. For example, a homologous series of alkanes, alkenes, alkynes, or other groups. Due to their low boiling points, lower alkanes are highly volatile. The general formula for the homologous series of alkenes is cnh2n where n is the number of carbon atoms.
Natures chemistry homologous series national 5 chemistry. The first few in the series are methane, ethane, propane, and butane. The family of alkane molecules has similar chemistry to one another because they are a homologous series. Thus, the homologous series of alkanes continues with pentane, hexane, heptane, octane, nonane, decane, and so on. Including activity building structures using the molymods also includes a simple worksheet. The alkanes and the alkenes are examples of homologous. With their repeated ch 2 units, the alkanes constitute a homologous series of organic compounds in which the members differ in molecular mass by multiples of 14. 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, the alkenes olefins, the carbohydrates, etc.
Alkanes are comprised of all single bonds and are saturated hydrocarbons. Homologous series a homologous series is a group of compounds with similar characteristics and the same general formula. Alkanes, alkenes, alkynes, alkadienes, formulaswhich differ in the number of hydrogen atoms, refer to hydrocarbons. Dec, 2011 the boiling points for a set of compounds in a homologous series can be qualitatively predicted using intermolecular force strengths. Among alkanes volatility decreases with increase in chain length. Significance and properties of the homologous series. For example, alkane, alkene and alcohol are separate homologous 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. You can tell that all the molecules in the series from methane to pentane have the same general formula. The alkenes comprise a series of compounds that are composed of carbon and hydrogen atoms with at least one double bond in the carbon chain. Butene has two isomers based on the location of the carbon double bond. 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. The organisation of organic compounds into the various different homologous series makes the study of organic chemistry more systematic, orderly and effective. The physical properties of the homologous series of alkenes c2 h4, and.
I talk about the difference between the three homologous series of hydrocarbons. Acyclic alkenes, with only one double bond and no other functional groups, known as monoenes, form a homologous series of hydrocarbons with the general formula c n h 2n. Alkanes do not decolourise bromine solutions, but alkenes decolourise bromine solutions rapidly. Each has its own general formula, homologous series, qualitative reactions, application. Such a family of compounds is known as a homologous. The members of each series differ from each other by the number of carbon atoms contained in the molecule.
Dec 24, 2018 lets take a brief look at the homologous series of alkanes for example. In first year organic chemistry, the first ten names of the homologous series are usually all that need to be memorized. Order in homologous series photograph shows the first members of various homologous series. The general formula for the homologous series of alkenes is c n h 2n where n is the number of carbon atoms. As with all hydrocarbons, the homologous series of alkenes will burn in oxygen through combustion. For example, a homologous series of alkanes, alkenes, alkynes or other groups.
The compounds are named as for the alkanes, but with the ending, ene. This nomenclature is of great importance for research, forecasting or practical application. Using their condensed structural formulas, rank the homologous series for a set of alkanes by their boiling point. An alkene will turn brown bromine water colourless as the bromine reacts with the. The compounds are named as for the alkanes, but with the ending, ene instead of ane. A homologous series of hydrocarbons that contains double carbon bonds. The homologous series of straightchained alkanes begins methane ch4, ethane c2h6, propane c3h8.
This group of compounds comprises a homologous series with a general molecular formula of c n h 2 n, where n equals any integer greater than one. The number of carbons continuously bonded together is an important structural feature and is described using the homologous series. The four homologous series studied at igcse are alkanes, alkenes, alcohols and carboxylic acids. A homologous series of alkanes may be formed by adding additional. Organic compounds in the same homologous series have the following. Similarly the series of alkene and alkynes also forms homologous series. Alkenes have two hydrogen atoms fewer than the corresponding alkane with the same number of carbon atoms. Alkanes form a homologous series of moleculesthose with the same general. The general formula for the homologous series of alkenes is cnh2n where n is the. Alkenes are unsaturated hydrocarbons because they contain a double bond between two of their carbon atoms. Organic compounds a homologous series is a family of organic compounds with the same general formula and functional group. Nov 12, 2017 made for a btec level 3 applied science class.
They contain the same functional group, the same general formula e. The general formula for alkenes are c n h 2n, where n is the number of carbons in the alkene. Aug 20, 2018 alkanes form a homologous series and so do alkenes. Aromatic compounds derive their names from the fact that. Such organic compounds that vary from one another by a repeating unit and have the same general formula form a series of compounds.
Homologous series is a series of compounds with similar chemical properties and same functional group differing from the successive member by ch 2. Methods that transform alkanes either to versatile alkenes or directly to functionalized. The names and formulae of these compounds will be dealt with in separate sections. Physical and spectroscopic properties of alkenes and. Mar 03, 2018 follows edexcel 91 combined science gcse powerpoint about alkanes, alkenes and alcohols. In an alkane, all 4 4 4 valencies of the carbon atom are satisfied with other hydrogen atoms. Alkenes have fewer hydrogens than alkanes and their general formula is cnh2n. Like the continuouschain alkanes, the 1 alkenes form a homologous series of compounds that show regular changes in physical properties with increasing chain length. The melting and boiling points of alkenes follow the same trends as those of alkanes, for the same reasons. The homologous series is a family or group of hydrocarbons or derivatives having the same functional group, same general formula and similar chemical properties.
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 group of chemicals which have similar chemical properties. Chemicals in the same homologous series will show a gradual variation in one property eg. Alkanes alkanes and alkenes gcse chemistry single science. They also have a similar trend in physical properties. Lets take a brief look at the homologous series of alkanes for example. The alkenes form a homologous series with general formula c n h 2n for cycloalkenes it would be c n h 2n2. Cbse ncert notes class 10 chemistry carbon and its compounds. Another factor that contributes towards alcohols higher boiling point is due to the existence of a hydroxyl group oh that replaced a hydrogen in. The first four alkanes in the homologous series retain their original names. Alkadienes are typical representatives of unsaturated. Alkanes such as triacontane may be components in petroleum products and may be released to the environment through the processing and combustion of petroleum products.
The simplest alkene, ethene, has two carbon atoms and a. All structured data from the file and property namespaces is available under the creative commons cc0 license. May 09, 20 how to grow loofa luffa for sponges late bloomer episode 15 duration. Start studying chemistry organic chemistry alkanes and alkenes. Among isomeric alkanes more the branching, greater is the volatility. No alkene has only one carbon atom in its molecule as no double bonds would be possible for the molecule called unsaturated hydrocarbons because they contain carboncarbon double bonds. In limited oxygen, alkenes undergo incomplete combustion to form carbon monoxide, carbon and water. The alkanes are a homologous series of hydrocarbons. Remembering that there must be one bond per hydrogen and four bonds per carbon, one can see that for the three simplest alkanes, there is only one configuration, or molecular structure that can exist, as shown in figure 37. Methane gas is the first member of the homologous series of alkanes. Methane, ethane, propane, butane and so on is a homologous series. Carbon chains of varying length have been observed in organic compounds having the same general formula.
Kaye kittrell late bloomer urban organic garden show recommended for you. Homologous series examples, answers, activities, experiment. N5 chemistry unit 2 topic 1 summary notes st ninians high school. A homologous series is a group of chemicals which have similar chemical properties and can be represented by a general formula. Chemical test for the presence of unsaturated hydrocarbons used to distinguish between an alkane and an alkene. How are alkanes, alkenes, and alkynes homologous series since. Covalent bonds are formed when atoms share pair of electrons. Oct 24, 2012 homologous series is a series where in the hydrogen atom is replaced by the same functional group in multiple carbon compounds. So, none of the hydrogen atoms are being replaced by a functional group. Rank these alkanes from highest to lowest boiling points 1. Igcse physical and chemical properties of hydrocarbons. The homologous series covered in gce olevel pure chemistry syllabus and other sec 4 ip chemistry syllabus in singapore are.
Jun 12, 2017 order in homologous series photograph shows the first members of various homologous series. Physical properties of alkanes chemistry assignment. Hydrocarbons are organic compounds that contain only carbon and hydrogen. Naming alkenes, iupac nomenclature practice, substituent, e z system, cycloalkenes organic chemistry duration. Some examples of homologous series are shown in the following table. Feb, 2019 for unsaturated hydrocarbons, refine the classification by indicating whether the compound is an alkene, alkyne, or arene. A homologous series is a group of compounds with the same homologous series, and successive members differ by a ch 2 group. Saturated hydrocarbons of the alkane class are characterized by single bonds sigma.
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