Question #67776

2 Answers
Sep 15, 2016

Yes there are coordinate bonds in the Lewis dot structure of #NO_2#


Nitrogen has five valence electrons. In the ground state the electron structure is # 1s^2 2s^2 2p^3#
The #2s^2# electrons are "paired" sharing the same orbital with no need for another electron. However in the Lewis dot structure these are the two electrons that are used to form the coordinate bonds with the second Oxygen.

The # 2p^3# electrons are all single electrons in different orbitals.
Each of these electrons are "free" to form bonds with electrons of different atoms. Two of these single atoms form a double bond with the first Oxygen atom.

The third #2p# electron remains a single dot (unpaired) in the Lewis dot structure.

However the Lewis dot structure does completely relate to reality. In reality a resonance structure forms with bonds shifting back and forth making use of all five valance electrons of the Nitrogen.

The electron orbital can be thought of as hybridizing so that what you have is four equal orbitals which can equally bond to the two sets of unpaired electrons from the two Oxygen atoms. The Lewis dot structure is not able to accurately illustrate this reality

Oct 22, 2016

Yes … and no.


It depends on how you generate the structure.

Yes … if you generate the structure from #"NO"# and #"O"#

This is common in physical chemistry.

#":Ö=N:" + "Ö:" → ":Ö=" stackrel(.)("N")^"+"-"Ö::"^"-"#̈

(Imperfectly drawn, but the best I can do in this editor)

Here, both of the lone pair electrons are forming the bond to the #"O"#.

In that sense, this is a coordinate bond from #"N"# to #"O"#.

However, once the bond has been formed, you can't distinguish these electrons from any other electrons in the molecule.

No … if you generate the Lewis structure by putting electrons between the atoms to give them an octet

This is common in introductory and organic chemistry.

Then, the electrons are coming from "out of the blue" and do not originally come from any specific atom.