Molecular Shapes

Hello!  I hope everyone had a great week and a great quiz!  The answers for Friday's quiz are as follows:

1.  Draw the Lewis Dot Structure for Calcium Chloride:

2.  Draw the Lewis Dot Structure for water

3.  Draw the Lewis Dot Structure for COCL2 indicating formal charges

4.  Draw all resonance structures for Sulfur Trioxide

I hope you all did well!  One reason for drawing Lewis electron dot structures is to be able to predict the three-dimensional geometry of molecules and ions.  Because the physical and chemical properties of compounds are tied to their structures, the importance of this subject cannot be overstated.  The valence shall electron-pair repulsion (VSEPR) model is a reliable method for predicting the shapes of covalent molecules and polyatomic ions.  Simply put, electrons want to stay as far away from other electrons as possible.  The simplest way to understand this model is to assume the electron pairs around the central atom are involved in only single covalent bonds.  These follow a AXn formatting where A is the central atom and X is the atoms connected to the center atom with n being the number of these atoms connected.  Here are some basic shapes:

Linear = AX2

Trigonal-planar = AX3

Tetrahedral = AX4

Trigonal bipyramidal = AX5

Octahderal = AX6

I would suggest studying these.... hint.... hint.....  Remember this is only if the central atom is surrounded by single bonds!

For Parents:

We will be having our science project fair in a month.  All students are required to pick a topic that is chemistry related, but can't be dangerous.  Some good ideas can be found at this web site : Chemistry project ideas.  Please have your child pick a topic by this Friday.  Thanks!