Superlesson
Project 6-3
Geometry
Chapter 6, Polygons and Polyhedrons
Regular polygons and polyhedrons occur frequently in nature. One place they occur is in the formation of molecules. Below, you will explore why some molecules take on the shape of one of the Platonic solids and how others are formed from a variation of these solids.
Part B, Regular Polyhedrons
1. Read a theory that predicts the Shapes of molecules. This theory concerns the number of electrons in the outermost principal energy level of an atom. It says that each atom in a molecule will have a shape which minimizes repulsion between electrons in the outermost principal energy level or valence shell of the atom. This means that the electrons in the valence shell are positioned to maximize the distance between each other. The positions of these valence electrons determine the shape of a molecule formed from the atoms. Two of the molecular shapes described in this article are the tetrahedron and the octahedron.
a. Methane (CH4) is a tetrahedral molecule. Which atoms form the vertices of the tetrahedron?
b. According to the VSEPR theory, why is the CH4 molecule shaped like a regular tetrahedron?
2. Refer to and page down the Shapes of molecules Web site for a picture of an octahedron.
a. Hexafluoride (SF6) takes on the shape of a regular octahedron. Which atoms form the vertices of the octahedron?
b. What role does the sulfur atom play in forming this octahedron?
3. Learn about a newly discovered carbon molecule called the "Buckyball," a nickname for "Buckminsterfullerine." You can build your own Buckyball at this Web site.
a. How many vertices does a Buckyball have?
b. What are at the vertices of the Buckyball?
c. Explain how the Buckyball can be formed from a regular icosahedron. Click on "Figure 1" to see a picture showing how to truncate the icosahedron.
d. Explain why truncating the icosahedron in this manner creates a polyhedron with 60 vertices.