Here's an example:
Mr. Stitt taught us a great way to draw the diagram that is easy for the class to remember.
First, here are the instructions.
1. Count up all the valence electrons.
2. Add or subtract electrons to account for any charges.
3. Put the least electronegative element in the center (except Hydrogen because it can only make one bond) and form one bound to out elements.
4. Complete octets (or duets in the case of Hydrogen around the outer atams first)
5. Create double or triple bonds to satisfy octects on the central atom.
6. If the entire compound is charged, put it in [ ] and place the charge on the outside top right corner of the bracket (ex: [ ]+)
7. Sulfur can actually acomodate 12 electrons (six bonds) and phosphorus can accomodate 10 electrons (5 bonds)
After you make your diagram, the best way to see if the lewis diagram was drawn correctly you have to check formal charges. To do this is to find one that is actually made by nature.
Ex:
(# of valence electrons on plain atom) - (# of valence electrons on atom in compound)
But you have to make sure you remember exceptions that are able to take place in the Octet Rule.
* Sulfur can have 12 electrons in it's valence (6 bonds)
* Phosphorus can have 10 electrons in its valence (5 bonds)
* Boron can have 6 electrons in it's valence (3 bonds)
These bonds are unusual but help the diagram work. When finding formal charges these bonds enable them to come out equal to nature.
