## 2C.5

Amy Luu 2G
Posts: 105
Joined: Wed Sep 18, 2019 12:19 am

### 2C.5

This problem asks us to draw the lewis structure for the reactive species. I am having trouble understanding the lewis structure for chlorine nitrate (ClONO2). In the solution, N has a double bond with O, a single bond with another O and another single bond with another O. One of the O with a single bond to N has 6 electrons (total valence of 7). The N has only 4 when is should have 5. Does N only have 4 because it gave an electron to O (also because O is supposed to only have 6 but in this case has 7?)

MMckinney_4H
Posts: 61
Joined: Sat Sep 28, 2019 12:16 am

### Re: 2C.5

First, I just set up the molecule as described in the problem. From there, I added all of the 22 other electrons onto the atoms to give them octets. At first I gave Cl 6 free electrons, Oxygen 4, Nitrogen 0 and each of the oxygens 6. However, with this setup, nitrogen didn't have an octet. So, I moved two of the electrons from one of the oxygens to form a double bond with nitrogen. This satisfied everyone despite the fact that the formal charges were a bit weird (one of the oxygens has a formal charge of negative one and the nitrogen has a formal charge of positive), it still adds up to a formal charge of 0 for the entire molecule. After messing around with it a bit more, you recognize that this is the best you can get. No, it isn't as perfect as we'd like to see, but it is the best, most stable structure.

rachel liu 3k
Posts: 56
Joined: Sat Aug 17, 2019 12:16 am

### Re: 2C.5

MMckinney_4H wrote:First, I just set up the molecule as described in the problem. From there, I added all of the 22 other electrons onto the atoms to give them octets. At first I gave Cl 6 free electrons, Oxygen 4, Nitrogen 0 and each of the oxygens 6. However, with this setup, nitrogen didn't have an octet. So, I moved two of the electrons from one of the oxygens to form a double bond with nitrogen. This satisfied everyone despite the fact that the formal charges were a bit weird (one of the oxygens has a formal charge of negative one and the nitrogen has a formal charge of positive), it still adds up to a formal charge of 0 for the entire molecule. After messing around with it a bit more, you recognize that this is the best you can get. No, it isn't as perfect as we'd like to see, but it is the best, most stable structure.

Do the individual formal charges of each atom always add up to the overall charge on the molecule? Thanks!

BeylemZ-1B
Posts: 95
Joined: Thu Jul 25, 2019 12:17 am

### Re: 2C.5

rachel liu 3k wrote:
MMckinney_4H wrote:First, I just set up the molecule as described in the problem. From there, I added all of the 22 other electrons onto the atoms to give them octets. At first I gave Cl 6 free electrons, Oxygen 4, Nitrogen 0 and each of the oxygens 6. However, with this setup, nitrogen didn't have an octet. So, I moved two of the electrons from one of the oxygens to form a double bond with nitrogen. This satisfied everyone despite the fact that the formal charges were a bit weird (one of the oxygens has a formal charge of negative one and the nitrogen has a formal charge of positive), it still adds up to a formal charge of 0 for the entire molecule. After messing around with it a bit more, you recognize that this is the best you can get. No, it isn't as perfect as we'd like to see, but it is the best, most stable structure.

Do the individual formal charges of each atom always add up to the overall charge on the molecule? Thanks!

This is something I have been wondering too. and i think no! not always. the most stable version of the molecule should actually just be 0, no matter the overall charge of the ion.

rachel liu 3k
Posts: 56
Joined: Sat Aug 17, 2019 12:16 am

### Re: 2C.5

BeylemZ-4A wrote:
rachel liu 3k wrote:
MMckinney_4H wrote:First, I just set up the molecule as described in the problem. From there, I added all of the 22 other electrons onto the atoms to give them octets. At first I gave Cl 6 free electrons, Oxygen 4, Nitrogen 0 and each of the oxygens 6. However, with this setup, nitrogen didn't have an octet. So, I moved two of the electrons from one of the oxygens to form a double bond with nitrogen. This satisfied everyone despite the fact that the formal charges were a bit weird (one of the oxygens has a formal charge of negative one and the nitrogen has a formal charge of positive), it still adds up to a formal charge of 0 for the entire molecule. After messing around with it a bit more, you recognize that this is the best you can get. No, it isn't as perfect as we'd like to see, but it is the best, most stable structure.

Do the individual formal charges of each atom always add up to the overall charge on the molecule? Thanks!

This is something I have been wondering too. and i think no! not always. the most stable version of the molecule should actually just be 0, no matter the overall charge of the ion.

Hi there! I talked to a TA and the formal charges of each atom MUST add up to the overall charge on the molecule. Gl on the midterm :)