Isomers: Structural Isomers & Stereoisomers
Learning Goals
I can define and use the following words correctly: structural isomer and stereoisomer.
I can differentiate between structural and stereoisomers as well as the two types of stereoisomers.
I can explain the concept of isomers in organic compounds and how variations in the properties of isomers relate to their structural and molecular formulae.
I can differentiate between structural and stereoisomers as well as the two types of stereoisomers.
I can explain the concept of isomers in organic compounds and how variations in the properties of isomers relate to their structural and molecular formulae.
LESSON OVERVIEW (SPECIFIC EXPECTATIONS: B2.1, B3.5)
Hook:
Activity: How many can you build?
Have students use a molecular model kit to build, draw, and name as many structures (straight chained, branched, or cyclic) using 6 carbons and 14 hydrogens. The condition is that they have to use all 20 pieces in each model.
Debrief: There are several possibilities of structures formed from just 6 carbon atoms. All of these structures have the same molecular formula (C6H14) but different structural formulas. These compounds are called ‘isomers’.
Teaching Strategy:
1. Nature of the Carbon Atom
2. Structural Isomers
Activity: How many can you build?
Have students use a molecular model kit to build, draw, and name as many structures (straight chained, branched, or cyclic) using 6 carbons and 14 hydrogens. The condition is that they have to use all 20 pieces in each model.
Debrief: There are several possibilities of structures formed from just 6 carbon atoms. All of these structures have the same molecular formula (C6H14) but different structural formulas. These compounds are called ‘isomers’.
Teaching Strategy:
1. Nature of the Carbon Atom
- Discuss the nature of the carbon atom and its four valence electrons that allow it to form bonds with up to four other atoms. This property of the carbon atom gives rise to a wide variety of structures that exhibit different chemical and physical properties.
2. Structural Isomers
- Have students explore structural isomers using the following isomer construction set tutorial, courtesy of Fred Senese at General Chemistry Online!
3. Stereoisomers: Optical & Geometric Isomers
The following animated videos provide a great explanation of optical and geometric isomerism. These can be used as introductory videos to introduce the types of stereoisomers or just after a brief lesson introducing the concept of isomerism in organic compounds and defining key terms such as chiral carbons and enantiomers. The third video below illustrates geometric isomerism through the use of molecular models. The visual/tactile learners would really benefit from an opportunity to explore isomerism through molecular models.
The following animated videos provide a great explanation of optical and geometric isomerism. These can be used as introductory videos to introduce the types of stereoisomers or just after a brief lesson introducing the concept of isomerism in organic compounds and defining key terms such as chiral carbons and enantiomers. The third video below illustrates geometric isomerism through the use of molecular models. The visual/tactile learners would really benefit from an opportunity to explore isomerism through molecular models.
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Consolidation:
Students will be given a ziplock baggie containing structural diagrams of organic compounds. Students will sort them into pairs of structural or stereoisomers. If it is a stereoisomer they are required to specify which type of stereoisomer it is. The teacher can circulate the classroom and obtain a quick formative assessment to see if students’ classifications are correct and use this opportunity to address any misconceptions that students might have. This activity can also be conducted on a smart board where students can come up to the board and sort the structures into categories with the help of peers in the classroom.
Students will be given a ziplock baggie containing structural diagrams of organic compounds. Students will sort them into pairs of structural or stereoisomers. If it is a stereoisomer they are required to specify which type of stereoisomer it is. The teacher can circulate the classroom and obtain a quick formative assessment to see if students’ classifications are correct and use this opportunity to address any misconceptions that students might have. This activity can also be conducted on a smart board where students can come up to the board and sort the structures into categories with the help of peers in the classroom.