Drawing Lewis structures on the chemistry AP test?

Question

Will they ask me to draw a Lewis structure of a complicated molecule like...CH2ClCOO-?
Because for the more complex molecules, I am so clueless when it comes to finding the central atom and even finding the right skeletal structure (which atoms are next to which).

If the AP test DOES ask us to draw lewis structures for the more complex molecules, how do you find the skeletal structure?
Or.. will I have to draw every possibility and use formal charges to find the most plausible one?

I'm fine at assigning electron bonds and lone pairs, but finding which atoms bond to which confuses me. especially when theres alot of different atoms to deal with.
Will I have to be able to do that on the AP test?
If so, HOW DO I DO IT?!

[AP test in like.. 2 weeks. panic panic panic. @_@]

Answer 1

On the AP Chem exam, often they only ask for Lewis structures of reasonable molecules, meaning not often not organic. What you find difficult is figuring out how to draw organic molecules, which tend to be extremely complex. So, they are not something that you should be worrying about. If you know how to draw the Lewis structures for most of the common ions and chemical compounds, you should be just fine.

For future reference, in most organic molecules, the C is the central atom with the other molecules added on the in the order in which they appear in the equation around the C atom. Remember, this is a general, rough rule.

For the common ions, remember normally the central atom is the one with the most open electron spaces, such as Carbon, with 4, or nitrogen, with 3.

Remember, do not panic. You have worked hard all year long, and in the end, with moderate studying, everyone will do just fine.

Answer 2

commencing on the top superb nook and shifting clockwise we are able to make 4 resonance structures that improve the P octet to ten. In all of those the P has a suited charge of 0 and one oxygen is likewise 0. The final resonance shape expands the P octet to twelve, yet isn't an somewhat solid shape with the aid of fact the less electronegative P has a extra unfavourable formal charge then the rather some O. the final resonance structures are the 4 on the backside. i will placed cs2 later.

Answer 3

Study well, there is no need to panic. In large molecules, there is no central atom but covalent bonding throughout.