Formal Charge

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Formal Charge

Postby salvadorramos3k » Fri Oct 25, 2019 8:33 pm

I'm confused on what the formal charge is. Is that the number that's superscripted next to the symbol for example Cl ^-? Can somebody also please explain to me which numbers go where in the equation for solving the formal charge? I was especially confused on where the S came from because what made sense to me ended up not being the right thing. Thank you :)

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Re: Formal Charge

Postby nehashetty_2G » Fri Oct 25, 2019 9:58 pm

So formal charge is different from ionic charge. Formal charge takes into consideration the bonding in terms of electrons for each individual atom in the compound. Therefore, Cl in a compound does not always have a formal charge of -1. It could also have a formal charge of 0. We don't have to know how people derived the formula for FC, therefore I recommend just remembering the components of the equation and practicing to see how it works out.

The example Lavelle used in class for SO4 2- and how the Formal charge changes for each atom in the compound depending on if it is in the form with all single bonds or single+double bonds demonstrates the FC concept very well, so I would recommend looking over that!

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Re: Formal Charge

Postby SajaZidan_1K » Fri Oct 25, 2019 10:53 pm

Formal charge can also help you determine whether or not a certain lewis structure is better than the other if there is more than one way to draw a lewis structure. The more stable the formal charge is, the better the lewis structure is.

Katherine Brenner 3H
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Re: Formal Charge

Postby Katherine Brenner 3H » Fri Oct 25, 2019 11:12 pm

Does anyone know where we could find an example of this in the textbook (please post a page number if possible)?


Hannah Lee 2F
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Re: Formal Charge

Postby Hannah Lee 2F » Fri Oct 25, 2019 11:26 pm

You can find an example of a question dealing with formal charge in Example 2B.4 (page 85)! There's also a short section devoted to formal charge that starts on page 84.

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