## Drawing Lewis Structures

Saachi_Kotia_4E
Posts: 68
Joined: Fri Sep 28, 2018 12:23 am

### Drawing Lewis Structures

When drawing Lewis structures, how do you know where the atoms are? Like what angles the atoms are? Sometimes they're all in a straight line, but other times they're at 90 degree angles.

MaanasO 1A
Posts: 72
Joined: Fri Sep 28, 2018 12:26 am

### Re: Drawing Lewis Structures

Hi Saachi!

So Lewis diagrams are based on how many atoms are bonded to a certain atom. CH4 has 4 hydrogen atoms bonded to the same carbon atom, so they'll look like a plus sign. We haven't done VSEPR models, so these diagrams don't actually represent how the molecule looks; they're just drawn that way for convenience.

Hope that helps!

Posts: 62
Joined: Fri Sep 28, 2018 12:15 am

### Re: Drawing Lewis Structures

Lewis structures are meant to represent where the electrons are and how the molecule is bonded, not an accurate visual representation

alanaarchbold
Posts: 68
Joined: Fri Sep 28, 2018 12:27 am

### Re: Drawing Lewis Structures

Does resonance somehow affect the shape of structures?

Ava Kjos 1D
Posts: 65
Joined: Fri Sep 28, 2018 12:19 am

### Re: Drawing Lewis Structures

No resonance won't affect the shape in the Lewis structures at all. To show resonance, you will need to draw multiple diagrams to show the different possibilities.

haleyervin7
Posts: 61
Joined: Fri Sep 28, 2018 12:15 am

### Re: Drawing Lewis Structures

When drawing Lewis structures that aren’t symmetrical, like ONF, does it matter which side the O or F go on?

Posts: 33
Joined: Fri Sep 28, 2018 12:18 am

### Re: Drawing Lewis Structures

When drawing Lewis structures, follow this format:
1) Count the number of valence electrons for each atom.
2) Count atom with lowest ionization energy as the central atom (H is never the central atom).
3) Arrange atoms symmetrically around central atom.
4) Calculate the formal charges so that they are as close to 0 as possible.
Exceptions:
- for cations, remove 1 electron for each +1 charge
- for anions, add 1 electron for each -1 charge

annabel 2A
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Joined: Fri Sep 28, 2018 12:18 am

### Re: Drawing Lewis Structures

How do we know how many resonance structures to draw?

abbydouglas1K
Posts: 65
Joined: Fri Sep 28, 2018 12:26 am

### Re: Drawing Lewis Structures

annabel 1 1F wrote:How do we know how many resonance structures to draw?

I think you use the amount of possible double bonds between the same atoms to determine how many resonance structures you can have.

g orloff 1J
Posts: 45
Joined: Fri Sep 28, 2018 12:16 am

### Re: Drawing Lewis Structures

the shape depends on the VESPR orientation which we haven't gone over yet but think about lone pairs as opposite charges so there is a positive side and negative side.

LeannaPhan14BDis1D
Posts: 57
Joined: Fri Sep 28, 2018 12:16 am

### Re: Drawing Lewis Structures

If the angles are determined by something we haven't gone over will we be tested and graded on specificity of our structures with those angles or will it not matter as much for this midterm.

Kelsey Li 3B
Posts: 34
Joined: Fri Sep 28, 2018 12:26 am

### Re: Drawing Lewis Structures

Since we didn't learn the VESPR orientation yet I don't think we need to worry about bond angles. What's most important is just making sure when you draw your lewis dot structure that it's drawn evenly. The lewis dot structure just represent where the electrons are and the type of bonds but we don't need to worry about the precise bond angles.

taywebb
Posts: 60
Joined: Fri Sep 28, 2018 12:15 am

### Re: Drawing Lewis Structures

Can anyone confirm my understanding of ionic and covalent bonding in regards to lewis structures? I believe that when you have an ion you use ionic bonding with the brackets and if the atoms are a neutral charge you use covalent bonding? Is there anything more specific to drawing these diagrams?

SummerLee1F
Posts: 18
Joined: Fri Sep 28, 2018 12:16 am

### Re: Drawing Lewis Structures

annabel 1 1F wrote:How do we know how many resonance structures to draw?

You just draw all of the possibilities of each bond. Example, let’s say there’s two H’s and one O. One H & O have a double bond. For the second resonance structure, you would just draw the double bond on the other H instead of the first one.

804994652
Posts: 68
Joined: Fri Sep 28, 2018 12:26 am

### Re: Drawing Lewis Structures

I'm still confused about the arrangement about the atoms. For examples TB (7th ed) 2C.3c says to draw the lewis structure of HClO3 and I arranged the atoms of oxygen and hydrogen around Cl. The solution manual put the H connected to the Oxygen instead. How would I have known to do this?