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### formal charge

Posted: Sun Nov 03, 2019 10:22 pm
When you are drawing lewis structures do you always need to solve for formal charge? Are there molecules that automatically do not have a formal charge and therefore don't need to solve the equation for?

### Re: formal charge

Posted: Sun Nov 03, 2019 10:24 pm
Technically, the equation for formal charge is just for you to check whether the structure you drew is the best and most stable structure. Unless it asks you for the formal charge, I guess you do not really need to solve it. However, it is recommended to check for formal charge.

### Re: formal charge

Posted: Sun Nov 03, 2019 10:27 pm
When drawing Lewis structures, it is necessary to make sure that the structure represents the lowest possible energy state. Calculating formal charge is one way to confirm that the structure you have drawn is the lowest possible energy structure for that compound. Atoms will always take the structure with the least energy, so if your structure has more energy (greater magnitude formal charge) then it is incorrect relative to a lower energy structure. There are other ways to check if the Lewis structure is in the lowest energy state, but professor Lavelle wants us to use formal charge.

### Re: formal charge

Posted: Sun Nov 03, 2019 10:33 pm
Formal charge helps you determine whether you have drawn the best structure possible, but you should not have to necessarily write it out unless it is asked.

### Re: formal charge

Posted: Mon Nov 04, 2019 11:32 am
Abigail Carter 4G wrote:When you are drawing lewis structures do you always need to solve for formal charge? Are there molecules that automatically do not have a formal charge and therefore don't need to solve the equation for?

When drawing lewis structures, calculating formal charge helps you determine the best lewis structure with the lowest energy. There are common molecules/atoms (such as a double bonded oxygen) that appear quite frequently so it would be convenient to know them to speed up the process of the Lewis structure. However, you can always just calculate it using the equation.

### Re: formal charge

Posted: Mon Nov 04, 2019 11:40 am
You need to solve for formal charge if the question is asking for the electron configuration with the lowest energy. I thought in class today Lavelle said that he wanted us to always show the configuration with the lowest energy so I would just solve accordingly every time.