CHEM 102 Chapter 4 Lecture 10 Outline of Last Lecture I. Alkyl Groupa. NamingII. CycloAlkanesa. Chartb. What they arec. NamingIII. Reactions of Alkanes and CycloAlkanesa. Typesb. NamingOutline of Current Lecture I. Unsaturated Hydrocarbonsa. DefinitionII. Alkenesa. Definition – what makes a molecule an Alkene?b. Table of Alkenes c. Bond angles & shapes of Alkenesd. Constitutional Isomerse. Naming Alkenesf. Cis and Trans Isomersg. Addition Reactions of AlkenesCurrent LectureChapter 4 : Unsaturated HydrocarbonsThese notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.Unsaturated Alkenes – Molecules with a double carbon to carbon bond somewhere in the molecule*Alkenes are formed by the LOSS OF A HYDROGEN from ADJACENT carbon**Alkenes have a molecular geometry of Trigonal Planar, therefore it’s bond angle is 120 degrees.An Alkane is tetrahedral so it’s bond angle is 109.5 Degrees*REMEMBER THE DIFFERENT ALKENES! MAKE FLASHCARDS!! (See Table Below) http://media.tumblr.com/tumblr_m3yt0ixFhC1qfqzbt.png*Methene is not on there because it is impossible to have a double bond connect to nothing, which is what it would do since there is only 1 carbon*Constitutional Isomers – Different carbon skeletons are possible, just like we did with Alkanes except the double bond is somewhere else rather than the methyl groupsRules for Naming Alkenes 1. Find the longest chain WITH THE DOUBLE BOND and that is the parent chain2. Change the ending of the name from –ane to –ene3. The double bond always gets numbered with the smallest possible number, no matter what the methyl group’s number’s will bei.e Number from the end closest the the double bond4. Name the double bond from the lowest numbered molecule it started on i.e so if it starts on carbon 2 and ends on carbon 3, you will name it after the 2 because that is the smaller number5. If a compound has 2 double bonds, the ending will be –adiene. Di because it has 2 double bonds and –ene because it is an Alkene.EX. You have a Heptene molecule with 2 double bonds, one starting on the third carbon and one starting on the 5th so you would name it… 3,5 – HeptadieneCis and Trans IsomersCis Isomers occur when a double bond in a compound breaks and picks up 2 big or 2 little molecules on the same side of the compound. Trans Isomers occure when a double bond in a compound breaks and picks up 2 big or 2 little molecules on opposite sides of the compoundAddition Reactions of AlkenesHydrogen – Basically, the double bond in a compound breaks, so the two carbons it broke from need molecules to fulfill the rule of 8 valence electrons, so 2 hydrogens connect to the carbons.Halogen – The double bond between two carbons break and they need to molecules to fulfill the 8 valence electrons rule, so two of the same halogens attach to the carbons. (Br, Cl, F can attach to those carbons)Hydrogen Halide – A double bond breaks and Hydrogen attaches to one carbon, and a Halogen attach to the other carbon that needs fulfillmentWater – A double bond breaks and Hydrogen attaches to one carbon and OH attaches to the other
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