Is it possible to determine resonance structures.....or no? I understand what it is but I am not sure how the drawings come about or even how to recognize them.

Answer 1

It's mostly a little practice and looking for other ways to write Lewis electron dot structures. Basically, here are the steps.
1. Determine the number of electrons available. This part is easy.
2. Determine how many electrons are needed based on the octet rule. This is not hard BUT not all compounds obey the octet rule.
3. Determine the number of bonds needed from 1 and 2.
4. Draw the Lewis electron dot structure.
5. See if any resonance structures can be drawn using the same number of bonds and the same number of electrons.
6. Determine the formal charge of each atom to help in deciding which structures are most likely.

Try this on something like carbonate 2- ion or nitrate 1- ion. You will see that it is obvious that the double bond needed can be shifted to any of the oxygen atoms.