Charged molecules lewis structure

[Sharon Chu 3I]

To do the lewis structure for charged molecules, do we do the lewis structure for the original(uncharged) molecule, and then add the charge in the corner to signify it is charged, or do we have to change the structure of the molecule. Can I have an example to understand it better? Like NH4 with a positive charge example he gave in lecture I do not really understand.

[Riya 14B-2]

Hey!

So when we are given the charge of a molecule, we have to represent this charge in the Lewis Structure Diagram by the amount of electrons depicted. I think the number in the corner you are talking about is the notation outside of the brackets around a diagram to indicate what the charge of the molecule is. Using NH4+ as an example, we count 9 valence electrons: Nitrogen= 5 e- 4 Hydrogen= 4e- (total of 9). But because we know that NH4+ has a positive charge of 1, we need to subtract one from this total. So now that we have 8 e-, we place nitrogen in the middle of the Lewis structure (because it has the lower ionization energy) and place the 4 hydrogens around it, forming an octet around the N. (2 e- per bond). In this case, we form a cation by removing one e- to match the +1 charge.

Hope this helps!

[SuryaDham 3E]

when you have a charge, count the electrons added or subtracted by the charge before you make your lewis structure. for NH4, since N has 5 valence e- and 4 hydrogens have 1 e- each, and the charge is +, you end up with 5+4-1, thus 8 e-. Make your lewis structure using this number.

[Alison King 3L]

When there is a charge you do the same thing as if there is no charge by counting the total number of valence electrons. For a positive charge, you then subtract one electron for each positive charge. So for 2+, you would subtract 2 electrons. Similarly, for negatively charged molecules you add the number of electrons based on the charge. After this, then you draw the lewis structure using this number