Lewis Structures

The entirety of this unit is based on the ability to create the BEST lewis structure for each bond.

There are a few guiding rules to doing that,  ut mostly it is just practicing and trial and error.

One rule is that electronegative elements do not like to carry positive charges, so if one does it is most likely not the BEST structure.

Another rule is that charges on elements prefer to be spread out over the entire bond, instead of all piled onto one elements. For example, if one O in NO3 has a -3 charge on it while the rest are at 0, there is a better Lewis structure possible.

One more thing to make certain is that the charges on each part of the bond correspond with the overall charge. You can't have 2, -1 O's on a bond and have the overall charge be +4.

Here's a picture demonstrating this concept:

Here are some additional links if you want some more help:

http://chemed.chem.purdue.edu/genchem/topicreview/bp/ch8/lewis.html

http://www.chem.ucla.edu/harding/lewisdots.html

http://antoine.frostburg.edu/chem/senese/101/bonds/faq/simple-lewis-structures.shtml