Molecular Geometry Lab - Part I

NOTE: Place the pointer over the structure then click and hold to rotate the structure. Click on the buttons below the structures to continually rotate the molecules or change the way they are displayed.

1. Using the structures given below, explain why methane, CH4, arranges itself in a tetrahedral shape rather than square planar.
 

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Spacefill       Ball & Stick Spacefill       Ball & Stick

 

2. Fill in the table and use your knowledge of electron density and electron-electron repulsion to determine which of the following is the correct structure for the generic molecule MX3. Explain your choice below the table.
 
electron interaction # of 90˚ interactions
bp - bp  
lp - bp  
lp - lp  
electron interaction # of 90˚ interactions
bp - bp  
lp - bp  
lp - lp  
electron interaction # of 90˚ interactions
bp - bp  
lp - bp  
lp - lp  

* bp ≡ bonding pair
* lp ≡ lone pair