[Joules23]

i can draw a compound with its bonds and lone pairs pretty well, but i cant ever seem to get its molecular/electronic shape right (unless its linear), are there any guides or rules that would help me with this? Also im looking for practice lewis dot problems, i have a test on this stuff friday and i really would like to just sit down and do maybe 50-100 of them, i would also need answers to see if im doing them right

[Yggdrasil]

When considering the geometry about a central atom, the electronic shape is determined by the number of electron domains/steric number which is the number of bonded atoms plus the number of lone pairs.  For example, the central oxygen in water has two bonded hydrogens and two lone pairs so has four electron domains.

The molecular shape is based on the electronic geometry and is determined by the number of lone pairs.  For a good reference, see the wikipedia page on VSEPR theory:

http://en.wikipedia.org/wiki/VSEPR

[AWK]

http://www.chem.purdue.edu/gchelp/vsepr/
http://winter.group.shef.ac.uk/vsepr/
http://www.chem.ox.ac.uk/vrchemistry/vsepr/intro/vsepr_splash.html
http://www.uwosh.edu/faculty_staff/gutow/VSEPR_TUTORIAL/shtml%20version/VSEPR_model.shtml
http://www.chemistrycoach.com/tutorials-1.htm