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Mirror, Mirror, on the Wall. A Study in Chirality. what an isomer is? how many kinds of isomers there are? (Hint – use your textbook index.). Isomers are different compounds that have the same molecular formula.
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Mirror, Mirror, on the Wall A Study in Chirality
what an isomer is? how many kinds of isomers there are? (Hint – use your textbook index.) Isomers are different compounds that have the same molecular formula. There are conformational, constitutional (structural), and stereoisomers. Do You Know...
Conformational Isomers • Parts of the molecule rotate freely around a single bond but do not change location on the molecule. • These isomers will not have different physical or chemical properties, since they can change their shape easily.
Conformational Isomers • All of these images are 1-propanol arranged in different conformations. • The order of attachment is the same in all.
Constitutional Isomers • Constitutional isomers have the same molecular formula, but the groups and/or atoms are attached to the molecule in a different order. • Constitutional isomers may also have different kinds of bonds within the molecules.
Constitutional Isomers • C3H7Cl can be either 1-chloropropane or 2-chloropropane. H H H | | | Cl—C—C—C—H | | | H H H H Cl H | | | H—C—C—C—H | | | H H H
Constitutional Isomers • C3H6O can have two different structures. • What are the names of these compounds? H H | | O=C—C—C—H | | | H H H H H \ | C=C—C—OH / | | H H H The first compound is called propanal. The second compound is 2-propen-1-ol.
Stereoisomers • In stereoisomers the atoms and/or groups are attached to the molecule in the same order, but they have a different orientation in space. • There are several different types of stereoisomers. We have already studied one type.
Cis and Trans Isomers • Recall from Chapter 12 (Section 12.2) that alkenes can exist as cis and trans isomers. • Cis and trans isomers are one type of stereoisomer. • They have the same atoms and/or groups, but they are attached to different sides of the double bond.
This structure is a cis isomer, with the groups both on the same side of the double bond in the molecule.
And this is a trans isomer, with the groups on opposite sides of the double bond.
Can You Match These? A D • Trans-2-pentene ___ • Trans-2-methyl-3-hexene ___ • Cis-2-butene ___ • Cis-2-pentene ___ C B A B C D
Stereoisomers • We will now begin to explore isomers based on the groups around specific carbon atoms within a molecule. This chapter will be taught by YOU using Power Point presentations!
Your Group Tasks • You will work in groups of three students, with each member of the group contributing to the presentation. • Each group will be assigned a different concept from within this chapter.
Your Group Tasks • You will use your textbook and Internet resources to gather information on your assigned topic. • Each group will make and photograph molecular models illustrating your topic. You may also use images from other sources with appropriate permission.
Your Group Tasks • Each group will create and present a Power Point presentation that teaches about their assigned topic. • Complete details for the project will be found on your handout.
Individual Responsibilities • Each student is responsible for learning the vocabulary from the entire chapter. • Each student is responsible for learning the material presented by their group and by the other groups.
Individual Responsibilities • Each student is responsible for learning any material presented by the teacher. • Each student will be individually assessed by written and manipulative tests.