Week 5-6 Achieve Homework #4

[Olivia D 3B]

Hi!

I am struggling to draw the other 2 major resonance structures and formal charges for the carbamate ion. I know that one of the resonance structures can convert the C-O single bond to a double bond. I am struggling to draw the second structure. If someone could explain this to me it would be greatly appreciated.

Thank you!!

[Mia Hansen 2I]

Hi! Yes, changing the C-O single bond to a double bond is one resonance structure. The other would be converting the N-C single bond to a double bond. This works because it gives N an octet with all shared electrons.

[Olivia D 3B]

How do I determine where to put the +1 and -1 charges?

[Shivani Sakthi 1l]

Hello! Resonance is defined as the characteristic of some lewis structures having multiple bonds in different locations. It is the blending of structures with the same arrangement of atoms but different arrangements of E. Therefore, we can find the resonance structures of the carbamate ions by modifying the covalent bonds between atoms, but still ensuring that the octet rule is met for each atom. Since N, O, and H are all in the 2nd period of the periodic table, they can only accommodate 8 valence electrons. To ensure that the octet rule is met in carbomate, we can remove the second covalent bond that bonds C and O, and shift the covalent bond to the other oxygen molecule. The new oxygen molecule with a double bond will have two lone pairs of electrons while the initial oxygen molecule will have 3 lone pairs of electrons.

To calculate the formal charge of each of the molecules, we use the formula Fc= V-(c+s/2) where V is the number of valence electrons, c is the number of lone pairs of electrons, and s is the number of shared electrons. You would put the calculated charge next to the atom that you calculate the formal charge for. Since the oxygen molecule that is single covalently bonded with carbon has 6 valence electrons, 6 lone electrons, and 2 shared electrons, the formal charge is 6-7= -1. This would be placed right beside the oxygen atom that has a single covalent bond with nitrogen.

The next resonance structure would consist of carbon having a double covalent bond with nitrogen, because it satisfies the octet rule. When the lone pairs on the oxygen are adjusted when removing the double bond, the formula for Fc can be used to calculate the formal charge.

[Anne Hogue 2J]

How do I determine where to put the +1 and -1 charges?

To determine where to put the +1 and -1 charges, you have to calculate the formal charge for each atom. The equation for this is Formal charge= valence electrons - (lone pair of electrons + shared number of electrons/2).