Lewis Structures (w/ same formal charge but different bonds)

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Steven Garcia 1H
Posts: 79
Joined: Fri Sep 28, 2018 12:16 am

Lewis Structures (w/ same formal charge but different bonds)

Postby Steven Garcia 1H » Thu Nov 01, 2018 6:00 pm

Hi!

If a Lewis structure for an atom can be written two different ways having the same formal charge, is it ideal to use the Lewis structure that let's say has a triple bond compared to another Lewis Structure of the same atom (with the same formal charge) that has a double bond instead?

An example of what I'm referring to is example 49.e in Chapter 3. The CN^- can be written with either a double bond or a triple bond having the same formal charge either way.

Diego Gonzalez 3F
Posts: 32
Joined: Fri Sep 28, 2018 12:26 am

Re: Lewis Structures (w/ same formal charge but different bonds)

Postby Diego Gonzalez 3F » Thu Nov 01, 2018 6:26 pm

Since a double bond is more stable than a single bond, I believe the same logic applies. So I believe that a triple bond, if the formal charge is lowest it can be, would be preferable.

Sara Sadrolsadat 1G
Posts: 39
Joined: Fri Sep 28, 2018 12:16 am

Re: Lewis Structures (w/ same formal charge but different bonds)

Postby Sara Sadrolsadat 1G » Thu Nov 01, 2018 9:42 pm

In the case of (CN)^-, I don't believe it can be written as a double bond because that would result in a total electron count of 12, when the formula only accounts for 10 (C: 4e + N: 5e + (-): 1e). Even if a double bond could exist between the two atoms, the formal charge would be 3- and not the needed 1-.


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