Formal Charge Shortcut

[Rebecca Chu 1C]

My TA said there was a shortcut she uses for calculating formal charge. (I have Rosie.) Does anyone know what it is? I didn't write down the shortcut.

[Chris Fults 1C]

Its just looking at the PTOE by seeing how many valence electrons the element has and then using # of valence electrons - number of electrons in the lewis structure. For example nitrogen has 5 valence electrons so if it had 7 electrons in the lewis structure the formal charge of nitrogen would be -2.

[Sam Metzger 1C]

I'm not sure if there is any kind of short cut to calculating the formal charge but all group 17 atoms have a formal charge of 0 when they only have one shared bond & six lone pair electrons and all group 16 molecules have a formal charge of zero when they have two shared bonds & four lone pair electrons.

[Molly Oakes 1A]

Instead of using the equation, I take the number of valence electrons that the atom has and subtract 1 for each lone pair electron and one for each single bond attached to that atom. Maybe this is what you are referring to.