Question

Question: Draw a valid Lewis structure for the molecule CH3NO in which there are no nonzero formal charges on any of the atoms. This structure should not include any bonds between N and O.
what do you do with the oxygen?

Answer 1

Answer :  The Lewis-dot structure of $CH_3NO$ is shown below.

Explanation :

Lewis-dot structure : It shows the bonding between the atoms of a molecule and it also shows the unpaired electrons present in the molecule.

In the Lewis-dot structure the valance electrons are shown by 'dot'.

The given molecule is, $CH_3NO$

As we know that carbon has '4' valence electrons, hydrogen has '1' valence electron, nitrogen has '5' valence electrons and oxygen has '6' valence electrons.

Therefore, the total number of valence electrons in $CH_3NO$ = 4 + 3(1) + 5 + 6 = 18

According to Lewis-dot structure, there are 12 number of bonding electrons and 6 number of non-bonding electrons.

Now we have to determine the formal charge for each atom.

Formula for formal charge :

$\text{Formal charge}=\text{Valence electrons}-\text{Non-bonding electrons}-\frac{\text{Bonding electrons}}{2}$

$\text{Formal charge on O}=6-4-\frac{4}{2}=0$

$\text{Formal charge on C}=4-0-\frac{8}{2}=0$

$\text{Formal charge on N}=5-2-\frac{6}{2}=0$

$\text{Formal charge on }H_1=1-0-\frac{2}{2}=0$

$\text{Formal charge on }H_2=1-0-\frac{2}{2}=0$

$\text{Formal charge on }H_3=1-0-\frac{2}{2}=0$

Hence, the Lewis-dot structure of $CH_3NO$ is shown below.

Answer 2

The mentioned molecule with formula, CH₃NO where no bond is found between N and O can be depicted as formamide is shown in the attachment below.  

The formal charges = Number of valence electrons for the atom (V) - the number of electrons in lone pairs (N) - 1/2 (number of electrons in bond pairs, B)

FC = V - N - B/2

Thus, there is a need to calculate valence electrons, electrons in lone pairs, and the number of electrons in bond pairs for each atom in the mentioned molecule.  

V or valence electrons on C = 4e, on H = 1e, on N = 5e, and on O = 6e.  

N or electrons in lone pairs on C = 0e, on H = 0e, on N = 2e, and on O = 4e.  

B or number of electrons in bond pairs for C = 8e, for H = 2e, for N = 6e, and for O = 4e.  

Thus, the formal charges for each will be,  

C = 4 - 0 - (8/2) = 0

H = 1 - 0 - (2/2) = 0

N = 5 - 2 - (6/2) = 0

O = 6 - 4 - (4/2) = 0

Lewis dot structure for the given molecule is given in the attachment below: