by Nathan Hickey & André Gagnier

Curricular expectations (SCH 4U): B. Organic Chemistry B3 demonstrate an understanding of the structure, properties, and chemical behaviour of compounds within each class of organic compounds. B2.3 build molecular models for a variety of simple organic compounds. B3.5 explain the concept of isomerism in organic compounds, and how variations in the properties of isomers relate to their structural and molecular formulae.

You have 2 minutes: In groups of two, Use a molecular kit and build C 6 H 14 in as many different ways as you can. Then draw your results. GO!

What is their chemical formula?

They both have the same chemical formula! So again, are they the same?

They're all C 5 H 12. So are they all the same? All different? In groups of 2,use a molecular kit to discover.

Begin with the Isomer Challenge on slide #3 followed by the questions on the next three slides. (Inquiry-based learning) Between every new question will be in-class discussions where the students must propose hypotheses and take a stand. Following this is an introduction to the term "isomer“ and the theory of constitutional isomers. End the period with the on-line Isomer Construction Set, with a few questions assigned as homework.Isomer Construction Set

To demonstrate that isomers have different physical and chemical properties, the students will evaluate the boiling point and density of the following compounds: Propanol Isopropanol After the labs, the rest of the period will be spent discussing why it is that isomers react differently (different electron density, different polarity, etc.).

Using molecular kits, explore the nature of stereoisomers. Practice exercises are posted on the class Wiki.Wiki Students are also asked to determine whether alkynes also have stereoisomers.

PROBLEMSOLUTION Students may think that changing the shape (ie. rotating a C-C bond) means a new isomer is created. Using molecular models, show that for it to be an isomer, bonds need to be broken and replaced. Rotations do not create isomers. Understanding that cis- and trans- geometric isomers are, in fact 2 different substances. Using pictures and molecular models to allow students to see the 3D configuration. Students think that isomers are always members of the same class of compound. (eg. the student can think that any isomer of an alcohol must also be an alcohol, when in fact it could be an ether). Using inquiry-based discovery, students will have to construct all the possible isomers. Using pictures of 2 molecules (alcohol and ether) and asking students to count the atoms. They will realize that the formulae are the same.

the Bunsen burners used to determine the compounds' boiling points (obvious fire and burn hazards). Proper care must be taken and safety goggles must always be worn. the organic compounds that we handle will have to be dealt with carefully. Some of them are toxic and all of them are flammable! Proper disposal must be ensured afterwards.

Assessment FOR learning Questioning based on answers given during isomer identification challenge Assessment AS learning Group-based work during isomer identification challenge and online activity Assessment OF learning Homework: Problem sets Laboratory: Properties of different isomers.

 Cis- and trans- fatty acids in foods ◦ trans-fatty acids are generally associated with health risks including coronary heart disease ◦ The mechanisms through which these compounds contribute to these health risks are under investigation  Octane rating of gasoline ◦ Simply, this rating can be used as a rough measure of the isomeric content in the fuel  Chiral drug industry ◦ Exploiting isomers in pharmaceuticals to gain better efficacy. ◦ Not to be discussed in depth as it includes classes of isomers outside the scope of the class

organic-and-bio/421680#web http:// organic-and-bio/421680#web  (This site has general information on organic chemistry and is very simple and straightforward) organic/organic.htmlhttp://chemed.chem.purdue.edu/genchem/topicreview/bp/1 organic/organic.html  (A more advanced site with information on organic chemistry) bin/senese/tutorials/isomer/index.cgihttp://antoine.frostburg.edu/cgi- bin/senese/tutorials/isomer/index.cgi  (A web-based isomer tutorial. This site contains the virtual isomer construction set)  (The isomerism exercises were obtained from this site)