## Easier way to calculate/remember?

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

Clarice Chui 2C
Posts: 101
Joined: Fri Aug 30, 2019 12:16 am

### Easier way to calculate/remember?

Is there an easier way to calculate this/remember it/shortcut?

Sarah Blake-2I
Posts: 153
Joined: Fri Aug 30, 2019 12:16 am

### Re: Easier way to calculate/remember?

Take the valence electrons and subtract how many dots and lines you see connected to the element. This will give you the formal charge.

TanveerDhaliwal3G
Posts: 105
Joined: Fri Aug 30, 2019 12:17 am

### Re: Easier way to calculate/remember?

You can count the number of dots and bonds of the atom and subtract that from the number of valence electrons to find the Formal Charge quickly

Julie Park 1G
Posts: 100
Joined: Thu Jul 25, 2019 12:15 am

### Re: Easier way to calculate/remember?

Formal charge:
# ve- a neutral atom of the element would have - (sum of unpaired electrons + bonds)

Note:
a. count each unpaired electron attached to the atom as a single value
b. count each bond as a single value

For example, say that Nitrogen was surrounded by 1 double bond and 2 unpaired valence electrons. You know that a neutral atom of nitrogen should have 5ve-. Therefore, to find the FC, you would do: 5(ve-) - ( 2 (for each bond in the double bond) + 2 (for each unpaired electron) )
To get 5 - (2+2) or 5-4 which equals 1. The formal charge would be +1
Note: this is just a random theoretical example... not sure if this specific situation is possible

serenabirkhoff_1K
Posts: 63
Joined: Sat Aug 17, 2019 12:15 am

### Re: Easier way to calculate/remember?

for me the easiest way to remember how to calculate formal charge is the formula. At first I was having trouble remembering but once you do enough practice problems with the formula you should remember it.

Kristina Rizo 2K
Posts: 105
Joined: Wed Sep 18, 2019 12:19 am

### Re: Easier way to calculate/remember?

julieepark wrote:Formal charge:
# ve- a neutral atom of the element would have - (sum of unpaired electrons + bonds)

Note:
a. count each unpaired electron attached to the atom as a single value
b. count each bond as a single value

For example, say that Nitrogen was surrounded by 1 double bond and 2 unpaired valence electrons. You know that a neutral atom of nitrogen should have 5ve-. Therefore, to find the FC, you would do: 5(ve-) - ( 2 (for each bond in the double bond) + 2 (for each unpaired electron) )
To get 5 - (2+2) or 5-4 which equals 1. The formal charge would be +1
Note: this is just a random theoretical example... not sure if this specific situation is possible

Hey i just wanted to say thanks for including the video link, I just watched it and I understand formal charge a lot better!

Julie Park 1G
Posts: 100
Joined: Thu Jul 25, 2019 12:15 am

### Re: Easier way to calculate/remember?

Kristina Rizo 3K wrote:
julieepark wrote:Formal charge:
# ve- a neutral atom of the element would have - (sum of unpaired electrons + bonds)

Note:
a. count each unpaired electron attached to the atom as a single value
b. count each bond as a single value

For example, say that Nitrogen was surrounded by 1 double bond and 2 unpaired valence electrons. You know that a neutral atom of nitrogen should have 5ve-. Therefore, to find the FC, you would do: 5(ve-) - ( 2 (for each bond in the double bond) + 2 (for each unpaired electron) )
To get 5 - (2+2) or 5-4 which equals 1. The formal charge would be +1
Note: this is just a random theoretical example... not sure if this specific situation is possible

Hey i just wanted to say thanks for including the video link, I just watched it and I understand formal charge a lot better!

No problem! :)

Nohemi Garcia 1L
Posts: 103
Joined: Fri Aug 02, 2019 12:15 am

### Re: Easier way to calculate/remember?

For the oxidation numbers I just recommend keeping an eye out for negatively charged ligands.