Topic 2: Basic Shape Recognition

 

Searching the database using the "shapes" search option is a great way to have students learn to recognize the basic molecular shapes.

There are a lot of shapes to choose from if the entire database is being used, so if you want to make sure that students are only looking at basic shapes for the time being (a.k.a. in a very introductory course) I suggest using the "entry level" data base which only includes simple diatomic, linear, bent, trigonal planar, trigonal pyramidal and tetrahedral molecules.

 

 

Suggested activity #1

You could have students do an exploration on their own to become familiar with the shapes (click "entry level" at the top, and then "select all" and “view” to see a list of molecules that fit the criteria. If you want to narrow down the shapes search, search by shape and then go back to the periodic table to deselect any atoms you do not want to have included in your search or if you have particular molecules in mind for them to look at do a text search for the name or formula of the compound. )This site is especially good for students to get a clear picture of the molecular shapes because they can explore at home, click and drag the molecules into all types of positions so they can see symmetry and understand the 3d nature of molecules without having to make models for all of the shapes. They can also get a feel for the approximate angles between atoms that are associated with the various shapes if students are asked to make some kind of table associating bond angles with the molecular shape.

 

 

We suggest exploring the database yourself first and then possibly picking out some of the structures you especially like to show the class or to ask the students to look at in particular. A projection of the rotatable structures make the structures come to life during a lecture, and can be used to supplement the models most teachers use to introduce basic molecular shapes.

 

 

Suggested activity #2

          Students can use the pdf files which are the Molecular Origami patterns for the molecule to make a physical model at home or in the classroom. No matter how good the digital technology is, sometimes there is simply no substitute for having a touchable 3-dimensional model.

 

 

Suggested activity #3

          A fun activity to make sure students are really comfortable with the basic shapes is to have them look at larger molecules and identify all the basic shapes that make up that molecule. (sort of a “Where’s Waldo?” activity) Click here to see the molecules we have found that would work well for this activity.