Determining Lewis Structure

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Olivia Young 1A
Posts: 60
Joined: Fri Sep 28, 2018 12:24 am

Determining Lewis Structure

Postby Olivia Young 1A » Thu Nov 01, 2018 3:19 pm

When you are trying to determine the lewis structure of a compound, how does the formal charge affect it? I remember learning that a compound is most stable when there is a neutral charge among all atoms, but I wasn't sure if the correct lewis structure is always the one with as many atoms having a formal charge of 0. Thanks!

Chris Freking 2G
Posts: 60
Joined: Fri Sep 28, 2018 12:29 am

Re: Determining Lewis Structure

Postby Chris Freking 2G » Thu Nov 01, 2018 4:26 pm

The correct Lewis structure is the one with as many atoms having a formal charge of 0. Sometimes for compounds like SO3 2- there are variations of the Lewis structure that all have the same overall formal charge which is where resonance comes into play (multiple possible lewis structures)

Sofia Ban
Posts: 80
Joined: Fri Sep 28, 2018 12:25 am

Re: Determining Lewis Structure

Postby Sofia Ban » Thu Nov 01, 2018 4:29 pm

Formal Charge of an atom indicates the gain or loss of an electron while forming covalent bonds. An easy way to understand this concept of formal charge and stability is to think about attaining the lowest formal charge for a given Lewis structure because the one with the lowest formal charges is the most stable. Knowing the formal charge on a particular atom in a structure is an important part of keeping track of the electrons and is important for establishing and predicting the reactivity and the most correct Lewis structure.

Hedi Zappacosta 1E
Posts: 66
Joined: Fri Sep 28, 2018 12:27 am

Re: Determining Lewis Structure

Postby Hedi Zappacosta 1E » Thu Nov 01, 2018 5:03 pm

A molecule is most stable when the formal charges all all the atoms in the molecule are zero. The formal charges of all the atoms will also always add up to the total charge of the molecule. Another rule is that if the formal charge of an atom in a molecule has to be negative, make sure the most electronegative atom has the negative charge. In other words, the central atom shouldn't have a negative charge.


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