Memorizing the Equation

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Ariel Fern 2B
Posts: 70
Joined: Fri Aug 30, 2019 12:17 am

Memorizing the Equation

Postby Ariel Fern 2B » Sun Oct 27, 2019 11:02 pm

Anybody have any tips to memorizing the Formal Charge equation? Or should I just keep practicing it to become "second nature?" I honestly keep having to reference my notes right now, so if anybody has tips for formal charge calculations or memorizing the equation, that would be great! Thanks!

Posts: 54
Joined: Sat Aug 17, 2019 12:15 am

Re: Memorizing the Equation

Postby NRobbins_1K » Sun Oct 27, 2019 11:10 pm

I imagine that on a test we will be given that equation, so if you want to memorize it anyway that's great but you probably won't need to. As far as remembering the equation, I think of it in terms of starting with the 'total' available (V) and subtracting the 'parts' that could be arranged in different ways (different relative L or S).

Eesha Sohail 1D
Posts: 65
Joined: Sat Aug 17, 2019 12:16 am

Re: Memorizing the Equation

Postby Eesha Sohail 1D » Sun Oct 27, 2019 11:14 pm

For the formal charge on each atom, I usually count up every lone pair electron and bond, and subtract the sum from the neutral number of electrons. I find understanding this conceptually an easier thing to do, as opposed to consulting the equation. After a while, doing this just became second nature.

Amy Pham 1D
Posts: 73
Joined: Fri Aug 09, 2019 12:15 am

Re: Memorizing the Equation

Postby Amy Pham 1D » Mon Oct 28, 2019 6:31 pm

Try to think of it not as an equation but just counting up the electrons! It is much less daunting that way, and it becomes far more intuitive. Just look at the atom in the Lewis structure and count how many dots you see as lone pairs, which wholly belong to that atom. Also count one for each bond you see, as that atom shares these electrons with another atom. And just subtract the number you counted from the atom's number of valence electrons. Overall, I just think more about counting than applying an equation :)

Alan Wu
Posts: 61
Joined: Sat Sep 14, 2019 12:16 am

Re: Memorizing the Equation

Postby Alan Wu » Fri Nov 01, 2019 5:56 pm

Formal charge for an atom = # of valence electrons - (# of lone electrons + # of bonds)

This should be easier than counting the number of shared electrons and the dividing it by 2. Just count the number of bonds that atom has in the lewis structure instead.

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