Hello, I hope you're doing well.
First of all, dang that's impressive you were able to type out lewis structures. I had to take a second to appreciate it.
Now down to business, I will assume that "best" and "worst" refer to "most stable" and "least stable," respectively.
The first question I ask myself, is...what's making this thing unstable?
In this case, it's the negative charge of the overall structure.
The world likes to maintain its own homeostasis just like everything else, and that involves not having charges on molecules when avoidable to increase stability.
Generally, this mean that very extreme charges (anything past +1 or -1) are very unstable and unnatural. Think about the last time you've seen a realistic oxygen with a -2 charge or carbon with a +2 charge -- chances are it reacts REALLY fast to escape that state.
A more niche thing we don't need for this problem: if the charges are equal, like 2 oxygens with a -1 charge, the one with more bonds will be more stable and less reactive. In the human body, we use oxygens with double bonds and single bonds for this reason!
Ok, the last building we need is the tool to identify the charges of each atom. Nitrogen has 5 valance electrons. When counting, we'll use a bond line as 1 valence electron and a lone pair as 2 valence electrons. If we go over or under, it'll have a negative or positive charge respectively. So if we count 6 valence electrons, there is a -1 charge, 7 valence electrons = -2 charge, 4 valence electrons = +1 charge, etc. 5 is neutral and happy!
We have the structures:
[:¨N=N=N¨:]- <--> [¨N≡N-¨N..:]- <--> [:N≡N=N¨:]- <--> [:¨N..-N-N¨..:]- . I'll add valence electrons below atoms:
[6=4=6]- <--> [5≡4-7]- <--> [5≡5=6]- <--> [7-2-7]- . I'll now add the charges of each atom:
[-1=+1=-1]- <--> [0≡+1--2]- <--> [0≡0=-1]- <--> [-2-+3--2]- . They all add up to -1 no worries!
Big picture here: high charge atoms with small bonds are not having a fun time and are definitely not stable. I'm looking at the 4th and 2nd molecules as being the first and second most unstable molecules because of this! Both have a -2 charge atom single bonded, and the 4th molecule has double that along with an unheard of +3 charge that should not be legal.
The most stable atoms would accordingly be the 1st and 3rd atoms as the first and second most stable. Although the 1st molecule has more nonzero charges, their symmetry stabilizes the molecule more than a one-sided -1. This isn't true for the unstable molecules because the large charges make symmetry irrelevant as partial charge polarities are no longer the glaring issue (if that is confusing either don't mind the further explanation above or feel free to message me to ask what I mean!!).
Finally, the best 3 overall, in order, would be 1st, 3rd, 2nd.
Feel free to message if you're confused on anything, if you have any questions, or if this helped so I come here more often!
