Page 1 of 1

Formal charge

Posted: Tue Oct 29, 2019 10:17 pm
by Dakota Walker 1L
When drawing lewis structures do we need to calculate all formal charge options in order to decide how the structure should be drawn? Or can you just draw it based on electrons and guess on the double bond.

Re: Formal charge

Posted: Tue Oct 29, 2019 10:54 pm
by Justin Sarquiz 2F
You should calculate the formal charges in order to see which structure has the lowest energy. Once you get the hang of it, calculating the formal charge only takes a couple of seconds, so it will not take up that much of your time.

Re: Formal charge

Posted: Wed Oct 30, 2019 12:36 am
by Abigail Sanders 1E
As was previously stated, formal charge does not always have to be calculated to find the lowest energy structure, however, it often aids in deciding which structure has formal charges closest to 0 for the central and outward atoms.

Re: Formal charge

Posted: Wed Oct 30, 2019 1:01 am
by aphung1E
Can someone explain how to find the lone pair electrons when trying to find the formal charge?

Re: Formal charge

Posted: Wed Oct 30, 2019 1:04 am
by aphung1E
While trying to find the formal charge, how do you find the shared electrons?

Re: Formal charge

Posted: Wed Oct 30, 2019 9:28 am
by Maya Pakulski 1D
aphung1G wrote:Can someone explain how to find the lone pair electrons when trying to find the formal charge?

When finding lone pair electrons you just count the pairs of electrons that are not bonded to another element. For example in the Lewis structure for water, the O has two bonds and two lone pairs because it has four unbonded electrons.

Re: Formal charge

Posted: Wed Oct 30, 2019 9:33 am
by Veronica_Lubera_2A
When a question asks for the most stable resonance structure, you have to draw the different lewis dot structures (only switching the placement of bonds) and calculate formal charges. The ones closest or equal to 0 will be the most stable and therefore be the answer.

Re: Formal charge

Posted: Wed Oct 30, 2019 10:14 am
by Brynne Burrows 3K
aphung1G wrote:Can someone explain how to find the lone pair electrons when trying to find the formal charge?

Whichever pairs of electrons that cannot be replaced by a bond when the Lewis structure is drawn out can be counted as a lone pair. It helps to see the picture in order to determine lone pair electrons.

Re: Formal charge

Posted: Wed Oct 30, 2019 2:17 pm
by Sara Richmond 2K
AN easy way to calculate formal charge of an atom is:

# of valence electrons for that element- number of dots-number of lines=formal charge

Re: Formal charge

Posted: Wed Oct 30, 2019 6:25 pm
by BCaballero_4F
I would recommend counting the formal charge so you have the most similar structure to what the real structure looks like.