Isomers Hydrocarbon Compounds

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					22.3 ISOMERS
CHAPTER 22
HYDROCARBON COMPOUNDS
 VOCABULARY TO KNOW
Isomers
  StructuralIsomers
  Stereoisomers          Take out your notes
  Geometric Isomers       and keep track of
   Trans configuration    ALL definitions!
   Cis configuration

  Optical Isomers

   Asymmetric carbon
    BEFORE WE BEGIN…

             Remember that all molecules are in reality 3-D!


                                 Video showing 3-D molecules-
                                 remember molecules are 3-D
                                 structures!




Photo source: www.wikimedia.og                                  Video source: Rasmol
   ISOMERS
          Isomers: Compounds that have the same
          molecular formula but different molecular
                         structures

           Different structure = different substance

                                        2       1           2
          1


              1                 2                   1   2



      1                             2       1                   2

Photo source: chemguide.co.us
STILL CONFUSED?



         Lets look further into the
          definition of an isomer
                 (2:40-3:32)
                                              Are these molecules isomers
 STRUCTURAL                                       or are they the same?
   ISOMERS
                                                                 1    2           3           4       5
 Structural
 Isomers:
 compounds that                                                                                           5
 have the same
 molecular                                                       1        2           3               4
 formula, but the
 atoms are joined
 together in a
 different order.
                                                                  1           2           3       4
 Photo source:
 http://www.slc.ac.nz/WorkshopClub/Workshop/problemsonstructuraliso                                   5
 mers.htm
               Which has lower                  STRUCTURAL
               boiling point?                     ISOMERS

                                               Different physical
                                                    properties
                                                   (mp & bp)

                                               High number of
                                                  branches
                                                      =
                                               low boiling point

Photo sources: www.lsbu.ac.uk, wikipedia.org
    STOP AND CREATE!


    Use your model kits to
       create 2 structural
        isomers for C6H4
   (there may be more than
           two options)




Photo source: www.kaboodle.com
STEREOISOMERS


 Stereoisomers: Molecules in which the
 atoms are joined in the same order, but the
 positions of the atoms in space are different.



                 Two Types:
                 1. Geometric
                 2. Optical
  GEOMETRIC                      Two Types:
   ISOMERS                       1. Cis-configuration
                                 Cis = same side
 Geometric
  Isomers:
 When atoms
  are joined in
  the same
                                 2. Trans-configuration
  order, but
  differ in their                   Trans = opposite side
  orientation of
  groups around
  a double bond.
 Photo source: chemguide.co.us
LET’S LOOK INTO THIS A LITTLE DEEPER




  Still wondering about stererisomers? And
        what does Cis and Trans mean?
                 (1:30-3:41)
       WHICH IS THESE IS CIS AND WHICH IS
                    TRANS?


                                             Same Side




                                     H          CH2CH3
Opposite Sides                           C     C
   (across)                     H3CCH2           H


Photo source: www.uwplatt.edu
    STOP AND CREATE!



              Use your model kits to create the
            Trans-configuration for this molecule:




Photo source: www.tennoji-h.oku.ed.jp, www.kaboodle.com
OPTICAL ISOMERS
                      Which is Asymmetric?


   Asymmetric
      carbon:
 A carbon with four
 different atoms or
  groups attached
 OPTICAL ISOMERS
              Optical Isomers:
 Pairs of molecules that differ only in the way
    that four different groups are arranged
     around a central atom. Mirror images!

            Are these molecules
            Optical Isomers? Why?
CH3CH2CH2                               CH3CH2CH2
                 CH3          CH3
            C                       C
 CH3CH2         Cl         CH3CH2       Cl
   OPTICAL ISOMERS
                       They are mirror images of each other
                        Take out your mirrors and lets play!




Photo source: astrobiology.berkeley.edutures
OPTICAL ISOMERS

                  Mirror Images
OPTICAL ISOMERS

                        Can not be Superimposed!
                    (no matter how you move them, you
                      can not make them look alike)




                    Try it with your own hands
Photo source: www.flicker.com
    STOP AND CREATE




  Use your model kits to create an example of an
    optical isomer & try to superimpose them.
                     Can you?

          (Remember you must have four different
            substituents around the carbon atom!)


Photo source: www.kaboodle.com
REVIEW


   1. How can you tell if two compounds are
                       isomers?
  They have the same molecular formula but different
                     structure

2. What different types of Isomers did we learn
                      about?
         Structural, Stereoisomers including both
             Geometric and Optical isomers
    REVIEW
                                    What type of Isomer is
                                            this?




              Geometric: Cis and Trans configurations
Photo source: www.chem.purdue.edu
REVIEW

         Draw the optical
             Isomer
REVIEW
   Is this a Cis or        Is this an
Trans configuration?   asymmetric carbon?




Cis configuration
                       Yes, this is asymmetric
BEFORE WE MOVE ON…



 Before we start our lab for this lesson, lets review
     how to name molecules that have branches
                (substituent groups).
                    (0:00-2:20)
    QUICK LAB TIME


                  Structural Isomers of Heptane
         -   Purpose: To build ball-and-stick models
             and name the eight structural isomers of
             Heptane (C7H16)

              Draw structures on paper to keep track of
                 all eight isomers: draw as condensed
                       and line-angle with names

Photo source: www.wikimedia.org
IN CLASS GROUP PROJECT

  Working in small groups and using the
            materials provided:

Create a poster outlining the different types
           of hydrocarbon isomers



   *Name and define each type and give
               examples!

				
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