## Formal Charge

$FC=V-(L+\frac{S}{2})$

Dustin Shin 2I
Posts: 64
Joined: Fri Sep 28, 2018 12:26 am

### Formal Charge

When we need to draw Lewis structures or even resonance structures, do we need to show calculations done for formal charges in order not to miss points on exams? Will that ever be an issue? The last test asked to show full work so I am wondering if this is necessary.

WilliamNguyen_4L
Posts: 65
Joined: Fri Sep 28, 2018 12:28 am

### Re: Formal Charge

Last test I just drew the most stable form of the lewis structure. I wrote all the calculations. If they ask for resonance then I think you should draw the resonance structures.

Sheridan Slaterbeck 1J
Posts: 62
Joined: Fri Sep 28, 2018 12:27 am

### Re: Formal Charge

I think you should always show your calculations for formal charge, each TA grades differently but my TA said the more work you show the greater chance you will earn more points.

Luc Lorain 1L
Posts: 59
Joined: Fri Sep 28, 2018 12:18 am

### Re: Formal Charge

For Lewis structures with equivalent resonance structures, I did the calculations for one of the structures, and put the appropriate formal charges around the other resonance forms. Otherwise, yeah you should do independent calculations for each resonance form.

Diana Sandoval 1K
Posts: 61
Joined: Fri Sep 28, 2018 12:25 am
Been upvoted: 1 time

### Re: Formal Charge

WilliamNguyen_4D wrote:Last test I just drew the most stable form of the lewis structure. I wrote all the calculations. If they ask for resonance then I think you should draw the resonance structures.

What's the difference between the Lewis structure and the resonance structure?

AlyssaBei_1F
Posts: 99
Joined: Fri Sep 28, 2018 12:17 am

### Re: Formal Charge

A resonance is a Lewis structure that have bonds in different equivalent locations.

Aleeque Marselian 1A
Posts: 60
Joined: Fri Sep 28, 2018 12:24 am

### Re: Formal Charge

In my opinion, it is always better to show work just in case. Especially if the grader prefers to see the steps.

katie_sutton1B
Posts: 61
Joined: Fri Sep 28, 2018 12:17 am

### Re: Formal Charge

It's obviously better if you do because of partial credit, but it's not necessary.

Arlene Linares 3A
Posts: 50
Joined: Fri Sep 28, 2018 12:25 am

### Re: Formal Charge

How many points was the FC worth on the midterm?

uhedlund
Posts: 38
Joined: Wed Nov 15, 2017 3:03 am

### Re: Formal Charge

It is always better to show work just in case, but generally for formal charge I do not think it is necessary

205458163
Posts: 33
Joined: Wed Jun 26, 2019 12:15 am

### Re: Formal Charge

In my opinion, the answer is yes, you should draw a figure of the structure. And you also should calculate the formal charge and show the calculation steps.

simmoneokamoto3K
Posts: 50
Joined: Mon Jun 17, 2019 7:22 am

### Re: Formal Charge

I wouldn't say you need to show all your work, but I definitely recommend it, in the worst case hypothetical you get the question wrong, you can, at the very least, get partial credit for showing your work.

Sisi Li 1F
Posts: 34
Joined: Mon Mar 11, 2019 12:15 am

### Re: Formal Charge

I'd say you should show your formal charge calculations, just to show that you know a certain lewis structure is correct. Could depend on the TA though.