Formal Charge and lone pairs


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DanielleNario1A
Posts: 35
Joined: Fri Sep 28, 2018 12:24 am

Formal Charge and lone pairs

Postby DanielleNario1A » Thu Nov 01, 2018 11:08 pm

For the lone and shared pairs should I count each electron in the lone pair or count one pair as one? And would each bond count as 1 or 2 bonds?

Nicole Elhosni 2I
Posts: 62
Joined: Fri Sep 28, 2018 12:28 am

Re: Formal Charge and lone pairs

Postby Nicole Elhosni 2I » Thu Nov 01, 2018 11:13 pm

When you are calculating the formal charge with the equation:
FC= (Valence electrons) - (lone pair electrons + shared electrons/2)
then the lone pair electrons will be counted as individuals, since it is asking for the number of electrons in the lone pairs and not the number of lone pairs. (for example, if an atom had three lone pairs, there would be three lone pairs but six lone pair electrons). The same goes with bonds. Each bond represents two electrons, so in the formula for formal charge you would put the number of electrons shared (so if there was one bond, it would be two electrons).

Michael Torres 4I
Posts: 92
Joined: Thu May 10, 2018 3:00 am
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Re: Formal Charge and lone pairs

Postby Michael Torres 4I » Thu Nov 01, 2018 11:34 pm

You should count each paired electron as one, and you should also see the bonds as having two electrons.

The formula to find the formal charge is the following.

Formal charge = valence electrons - (lone electrons + 0.5(bond electrons))

Therefore, although each bond has two electrons, you will be adding only one per bond to the lone electron number because of the 0.5.


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