Which Chemical Species Has the Lowest Energy Based on Formal Charge?

[omni]

i found the Formal charge of 3 Chemical species, now i asked to decide which one יhave the most low energy.

how can i know it, all have -3 at the sum.

i need help in this section.thanks.

 

[ptolema]

What do you mean by 'the lowest energy'? I can tell you which one is the most stable: the first one. Since As has d-orbitals, it is able to form more than 4 bonds. Combine this with the fact that oxygen tends to form double bonds, and it is readily seen that the first is the logical choice.

The most stable structure is the one with:
a) the lowest sum when the absolute values of the formal charges are added
b) the largest negative formal charge on the most electronegative element (when 2 or more
structures have the same lowest sum)

 

[omni]

hi thank you very much.
you really helped me :)

but i think you have a mistake if we work with the rules from what you given and since o is more electronegative than As so if we follow after rule b the most stable structure is the one in the center.