Lesson 2
Mass Spec (Molecular Ion)
Learning Intention: Use the molecular ion to determine the number of carbons in an unknown organic molecule.
Success Criteria
5. I can identify the molecular ion on mass spec data and use that to determine the carbon length of a molecule.
3. I can identify structure isomers from a molecular formula.
Learning Tasks
Do Now - Play IR Spectra Gimkit
Copy down Ms Garlick's notes on mass spec (molecular ion).
Work on identifying the functional groups and the number of carbons in the Combination Questions Packet.
If needed, watch Ms Garlick's extra notes on using the empirical formula as part of her final revision notes.
Homework
Continue working on fuctional group and number of carbon identification in the Combination Questions.
Teacher Notes
First set of notes, explain how the machine works and how to get achieved for this spectra (identify the molecular ion and the base peak).
Second set of notes, talk about isotopes so they know how to identify N, Cl, and Br. Then, show them how to calculate the number of carbons in the molecule. My trick is to first find the mass of the functional group, then add 14 (CH2) until I'm one away from the molecular ion.
Make sure to also mention that sometimes it will be hard to see the molecular ion because the molecule is unstable and breaks apart. If that is the case, I will either label it or provide them a hint like an empiral or molecular formula. Show them in the practice questions what that looks like.
Note that this took 2 sessions.
This lesson was used on Tuesday, May 28th, 2024, Term 2 Week 5. That is when this webpage was last updated.
Tuesday, June 4th, 2024 was used as a study session to give students a chance to process this material.