Why do some Lewis structures have exceptions?

[QuarkCharmer]

Homework Statement

ICl_4^-

Homework Equations

n/a

The Attempt at a Solution

I has 7 valence, Cl has 7*4. Ideally, they would be 8 and 8*4, and so.
(40-35+1)/2 = 2 bonds. //the +1 is from the negative charge of the ion

There are simply not enough bonds to go around, so when I draw it out I just give a single bond to everything that needs it. Then I make sure that they all satisfy the octet rule and give the leftover electrons to the central atom (I)? So I end up with 4 Cl's with 6 electron dots single bonded to the I, which has an additional 2 lone pair. So I has 12 electrons?

I can understand this one as an example, but what happens when I come up with an odd number of electrons? Is there a decent guide to this somewhere? The only ones that I found are horrible. Also, I am confused as to how exactly you know to make a molecule have more than one central angle?

 

[cep]

It seems to me like you're sort of working backwards, and it's confusing you. Here's a guide: http://http-server.carleton.ca/~rburk/chem1000/on_line_tuts/vsepr/ICl4_.htm