EXPERIMENTOrganic Structures Shapes and Isomerism – Part 2Hands-On Labs Inc. Version 42-0185-00-02Review the safety materials and wear goggles whenworking with chemicals. Read the entire exercisebefore you begin. Take time to organize the materialsyou will need and set aside a safe work space inwhich to complete the exercise.Experiment Summary:In this experiment you will learn about the IUPACnaming system. You will also use a molecularmodeling kit to investigate butane geometricand structural isomers aromatic hydrocarbons resonance structures alkynes alcohols aldehydes ketones ethers carboxylic acids and amines.www.HOLscience.com1© Hands-On Labs Inc. ExperimentOrganic Structures Shapes and Isomerism – Part 2Learning ObjectivesUpon completion of this laboratory you will be able to:??Assemble molecules with molecular modeling kits preparing single bonds double bonds andresonance structures.??Build molecular models to construct three-dimensional models of organic compounds.??Draw the structural formula of organic compounds.??Define aromatic hydrocarbons resonance structures alkynes alcohols aldehydes ketones ethers carboxylic acids and amines.??Compare and contrast geometric and structural isomers.Time Allocation: 2.5 hourswww.HOLscience.com2©Hands-On Labs Inc. ExperimentOrganic Structures Shapes and Isomerism – Part 2MaterialsStudent Supplied MaterialsQuantity111Item DescriptionCamera digital or Smartphone (Optional)PaperPencilHOL Supplied MaterialsQuantity1Item DescriptionMolecules of Life Simulation kitNote: To fully and accurately complete all lab exercises you will need access to:1. A computer to upload digital camera images.2. Basic photo editing software such as Microsoft Word® or PowerPoint® to add labels leader lines or text to digital photos.3. Subject-specific textbook or appropriate reference resources from lecture content orother suggested resources.Note: The packaging and/or materials in this LabPaq kit may differ slightly from that which is listedabove. For an exact listing of materials refer to the Contents List included in your LabPaq kit.www.HOLscience.com3©Hands-On Labs Inc. ExperimentOrganic Structures Shapes and Isomerism – Part 2BackgroundMolecular modeling kits are used to construct three-dimensional models of organic compounds.Organic compounds can also be modeled on paper by writing and drawing the structural formulaof the compound. Structural formulas can be more complete than molecular formulas as theyindicate the position of attachment of each atom and the type of bond formed. Molecular modelsallow for a visual understanding of both the three-dimensional nature of the molecule(s) and thespatial relationships that occur between molecules in a compound.The molecular modeling kit included with this experiment contains atoms represented as plasticshapes which are designed to receive connecting bonds. The molecular modeling kit containsatoms in a variety of colors with each color representing atoms from a specific chemical element.See Table 1.Table 1. Molecular Modeling KeyAtomColorCarbon (C)BlackHydrogen (H)WhiteChlorine (Cl)GreenNitrogen (N)BlueOxygen (O)RedIn the modeling kit a single bond is represented by the shorter plastic stick and is used to connecttwo atoms. A double bond is represented by the longer more flexible plastic stick. The flexibilityallows the plastic sticks to curve as they create double or even triple bonds.AlkenesAlkenes are hydrocarbons containing one or more double bonds. Alkenes are named according tothe longest continuous chain of carbon atoms adding “-ene” to the end of its name and using anumber to indicate the position of the double bonds if necessary. The simplest alkene is ethene CH2=CH2 also known by the common name ethylene.The double bond in alkenes represents four electrons. The extra pair of electrons bonded betweentwo carbon atoms makes alkenes chemically more reactive than the corresponding alkane. A listof common alkenes is shown in Table 2.www.HOLscience.com4©Hands-On Labs Inc. ExperimentOrganic Structures Shapes and Isomerism – Part 2Table 2. Examples of Alkenes.Molecular FormulaC2H4Number of Carbon Atoms2NameEtheneC3H63PropeneC4H84ButeneC5H105PenteneC6H126HexeneC7H147HepteneC8H168OcteneC9H189NoneneC10H2010Decenewww.HOLscience.com5©Hands-On Labs Inc. ExperimentOrganic Structures Shapes and Isomerism – Part 2Exercise 1: Organic Structures Shapes and IsomerismIn this exercise you will build and examine organic compounds.Part 1: Butane and Isomers1. Gather the modeling kit.2. Use the modeling kit to build a model of butane (CH3-CH2-CH2-CH3).3. Rotate the single carbon-carbon bonds so that the end methyl groups are on opposite sidesof the center carbon atoms.4. Rotate the single carbon-carbon bonds so that the end methyl groups are on the same side ofthe center carbon atoms.5. Use the models that you manipulated in Steps 3 and 4 to determine if the 2 models areisomers of one another and record your answer in Data Table 1 of your Lab Report Assistant.Explain your answer.6. Determine the bond angles and the molecular geometry surrounding the carbon atoms andrecord your answer in Data Table 1.7. Use the modeling kit to build a model of cis-2-butene where both methyl groups are on thesame side of the double bond. See Figure 1.Figure 1. Cis-2-butene8. Try to rotate or “spin” the center carbon atoms. Record your experience in trying to rotate adouble bond in Data Table 1.9. Determine the bond angles and the molecular geometry surrounding the 2 center carbonatoms of cis-2-butene and record your answer in Data Table 1.10. Use the modeling kit to build a model of trans-2-butene where the end methyl groups are onthe opposite sides of the double bond.11. Determine if it is possible to convert between cis-2-butene and trans-2-butene withoutbreaking bonds and record in Data Table 1.www.HOLscience.com6©Hands-On Labs Inc. ExperimentOrganic Structures Shapes and Isomerism – Part 212. Cis-2-butene and trans-2-butenes are called geometric isomers of one another. Why do youthink they are given this name? Record your answer in Data Table 1.13. Define the term structural isomer and explain how it differs from a geometric isomer. Recordyour answer in Data Table 1.14. Review the compound pairs in Data Table 2 of your Lab Report Assistant. Determine thename of each compound and record in Data Table 2. Then classify each compound pair asgeometric isomers structural isomers or not isomers and record in Data Table 2. An exampleis shown below in Figure 2.Figure 2. Example for Step #14www.HOLscience.com7©Hands-On Labs Inc. ExperimentOrganic Structures Shapes and Isomerism – Part 2Part 2: Aromatic Hydrocarbons Resonance and AlkynesBenzene is probably the most recognizable example of an aromatic hydrocarbon and is a specializedalkene. Two different representations of benzene are shown in Figure 3; the Lewis structure andthe shorthand version. Drawing the hexagon ring with a circle inside implies that each point is acarbon with 4 bonds 3 to the other carbons and 1 to the hydrogen.Note: Always be careful to include the circle inside for benzene or you may be drawing cyclohexane!Figure 3. Benzene1. Use the modeling kit to construct a model of benzene.Note: This will be a bit difficult with your model kit. First connect 6 carbons in a ring with 6short sticks then take the slightly longer sticks and form 3 double bonds. Place the white sticksand hydrogens on the 6 remaining prongs. You will see a planar structure with the 6 hydrogens allbonded to carbons in the same plane.Note: The alternating single/double bond system is only one representation of this unique molecule.As you can see it would be possible to move all the double bonds to the next carbon atom. This iscalled “resonance” when you can draw 2 or more identical structures for the same compound. It hasbeen shown that actual structure of benzene contains 1.5 bonds between each carbon.2. Determine the molecular geometry of the carbons in benzene and record in Data Table 3 ofyour Lab Report Assistant.www.HOLscience.com8©Hands-On Labs Inc. ExperimentOrganic Structures Shapes and Isomerism – Part 23. Draw the structural formula for methylbenzene commonly called toluene. Insert the drawinginto Data Table 3.AlkynesAlkynes are hydrocarbons containing 1 or more triple bonds. Alkynes are named according to thelongest continuous chain of carbon atoms using a number to indicate the position of the triplebonds if necessary. The simplest alkyne is ethyne CHCH also known by the common name acetylene.4. Use the modeling kit to build a model of 1-propyne.5. Draw the structural formula for 1-propyne and insert the drawing into Data Table 3.Part 3: Functional GroupsThe behavior of organic molecules is governed by the presence of functional groups combinationsof atoms that act as chemically reactive sites. Compounds with the same functional group willhave many similar properties and undergo similar chemical reactions. Double and triple bondsare also functional groups.You will build the following molecules recognize functional groups and review the concepts fordrawing Lewis Structures and the VSEPR Theory. You will not be asked to name these moleculesor understand the chemical and physical properties.AlcoholsAlcohols have the general formula R-OH where “R” represents an alkyl group and the “OH” iscalled a hydroxyl group.Note: As the OH is bonded covalently to a carbon and there is not a metal present it does not comeoff as a hydroxide ion. In other words this is not an ionic compound.1. Use the modeling kit to build a model of 1-propanol (C3H7OH).Note: 1-propanol is commonly called propanol or propyl alcohol.2. Draw the structural formula for 1-propanol and insert the drawing into Data Table 4 of yourLab Report Assistant.3. Determine why oxygen is represented with a “bent” structure and record your answer in DataTable 4.4. Use the modeling kit to build a model of 2-propanol (C3H7OH).Note: 2-propanol is commonly called isopropanol or isopropyl alcohol.www.HOLscience.com9©Hands-On Labs Inc. ExperimentOrganic Structures Shapes and Isomerism – Part 25. Draw the structural formula for 2-propanol and insert the drawing into Data Table 4.Ethers Aldehydes and KetonesEthers have the general formula R-O-R’ where “R” and “R’” represent alkyl groups.1. Use the modeling kit to build a model of dimethyl ether (C2H6O).2. Draw the structural formula for dimethyl ether and insert the drawing into Data Table 5 ofyour Lab Report Assistant.3. Determine the relationship that exists between ethanol (C2H6O) and dimethyl ether (C2H6O).Record your answer in Data Table 5.Note: It may be helpful to build the model of both compounds to help answer the question.Aldehydes and ketones have the general formula R – C – R’ where “R” and “R’” represent alkylgroups. For aldehydes at least one of the alkyl groups must be hydrogen.4. Use the modeling kit to build a model of methanal (CH2O).Note: Methanal is the simplest aldehyde. Methanal is commonly named formaldehyde.5. Draw the structural formula for methanal and insert the drawing into Data Table 5.6. Determine the molecular geometry of the carbon in the aldehyde and record your answer inData Table 5.7. Use the modeling kit to build a model of 2-proanone (C3H6O).Note: 2-propanone is also commonly named acetone.8. Draw the structural formula for 2-propanone and insert the drawing into Data Table 5.9. Determine the relationship between propanal and propanone and record your answer inData Table 5.Carboxylic Acids and AminesCarboxylic acids have the general formula RR’C=O where “R” and “R’” represent functionalgroups. When naming a carboxylic acid the carbon attached to the oxygen is the first carbon inthe chain and the longest chain beginning with that carbon sets the prefix for the name. The “-e”is dropped from the chain name and “-oic” acid is added. Some carboxylic acids can be derivedfrom benzene where the carboxylic acid group is attached to the benzene ring.1. Use the modeling kit to build a model of ethanoic acid (CH3COOH).Note: Ethanoic acid is also commonly named acetic acid or vinegar.www.HOLscience.com10©Hands-On Labs Inc. ExperimentOrganic Structures Shapes and Isomerism – Part 22. Draw the structural formula for ethanoic acid and insert the drawing into Data Table 6 of yourLab Report Assistant.3. Use the modeling kit to build a model of benzoic acid (C6H5COOH).4. Draw the structural formula for benzoic acid and insert the drawing into Data Table 6.Amines have the general formula of R3N where “R” represents any alkyl group or a hydrogen.Amines are named by listing the names of the 3 alkyl groups followed by the “-amine” suffix.5. Use the modeling kit to build a model of methylamine (CH3NH2).Note: Remember that the blue tetrahedron piece represents nitrogen.6. Draw the structural formula for methylamine and insert the drawing into Data Table 6.7. Take apart all models and return the modeling kit to your LabPaq for future use.Questions:A. Describe the difference between an aldehyde and a ketone.www.HOLscience.com11©Hands-On Labs Inc. ExperimentOrganic Structures Shapes and Isomerism – Part 2Organic Structures Shapes and Isomerism:Part 2Hands-On Labs Inc. Version 42-0185-00-02Lab Report AssistantThis document is not meant to be a substitute for a formal laboratory report. The Lab ReportAssistant is simply a summary of the experiment’s questions diagrams if needed and data tablesthat should be addressed in a formal lab report. The intent is to facilitate students’ writing of labreports by providing this information in an editable file which can be sent to an instructor.Exercise 1: Organic Structures Shapes and IsomerismData Table 1. ButaneQuestionAnswerAre the models isomers?Bond angles and molecular geometryDescribe the experience trying to rotate adouble bondBond angles and molecular geometry of the 2center carbon atoms of cis-2-buteneIs it possible to convert between cis-2-buteneand trans-2-butene without breaking bonds?Why are cis-2-butene and trans-2-butene referred to as geometric isomers?Define the term structural isomer and explainhow it differs from a geometric isomer.www.HOLscience.com12©Hands-On Labs Inc. ExperimentOrganic Structures Shapes and Isomerism – Part 2Data Table 2. Reviewing Compounds#1BrHBrBrandC=CHC=CBrHCompound NameHCompound NameAre #1 geometric isomers structural isomers or not isomers?#2CH3CH3CHCH3andCH3Compound NameCH 2CH 2CH3Compound NameAre #2 geometric isomers structural isomers or not isomers?#3ClClCH3CHCH 2andCH3ClCHCH 2ClCompound NameCompound NameAre #3 geometric isomers structural isomers or not isomers?www.HOLscience.com13©Hands-On Labs Inc. ExperimentOrganic Structures Shapes and Isomerism – Part 2Data Table 3. BenzeneQuestionAnswerWhat is the molecular geometry of the carbonsin benzene?Structural formula of methylbenzeneStructural formula of 1-propyneData Table 4. AlcoholsQuestionAnswerStructural formula of 1-propanolWhy is oxygen represented with a “bent”structure?Structural formula of 2-propanolwww.HOLscience.com14©Hands-On Labs Inc. ExperimentOrganic Structures Shapes and Isomerism – Part 2Data Table 5. Ethers Aldehydes and KetonesQuestionAnswerStructural formula of dimethyl etherWhat is the relationship that exists between ethanol (C2H6O) and dimethyl ether(C2H6O)?Structural formula of methanalMolecular geometry of the aldehydeStructural formula of 2-propanoneWhat is the relationship betweenpropanal and propanone?www.HOLscience.com15©Hands-On Labs Inc. ExperimentOrganic Structures Shapes and Isomerism – Part 2Data Table 6. Carboxylic Acids and AminesQuestionAnswerStructural formula of ethanoic acidStructural formula of benzoic acidStructural formula of methylamineQuestions:A. Describe the difference between an aldehyde and a ketone.www.HOLscience.com16©Hands-On Labs Inc.
