lewis structures

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Midori Hupfeld 3D
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Joined: Fri Aug 30, 2019 12:17 am

lewis structures

Postby Midori Hupfeld 3D » Sun Oct 27, 2019 11:55 pm

How do we determine which atom will be the center of the structure if there is more than two different atoms? For example in 2B.11 in the homework.

Serena Siddiq 3D
Posts: 51
Joined: Fri Aug 30, 2019 12:17 am

Re: lewis structures

Postby Serena Siddiq 3D » Sun Oct 27, 2019 11:56 pm

The one that goes in the center is whichever one has the lower ionization energy! I would also make sure you are making the Lewis structure symmetrical, like CO2 would have C in the middle and the two Os on each side. Hope this helps!
Last edited by Serena Siddiq 3D on Sun Oct 27, 2019 11:57 pm, edited 1 time in total.

Alice Chang 2H
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Joined: Fri Aug 30, 2019 12:18 am

Re: lewis structures

Postby Alice Chang 2H » Sun Oct 27, 2019 11:57 pm

Hey according to the website https://chem.libretexts.org/Courses/University_of_Illinois%2C_Springfield/UIS%3A_CHE_267_-_Organic_Chemistry_I_(Morsch)/Chapters/Chapter_01%3A_Structure_and_Bonding/1.03%3A_Lewis_Structures :
The central atom is usually the least electronegative element in the molecule or ion; hydrogen and the halogens are usually terminal.

Hope this helps!

Megan Vu 1J
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Joined: Thu Jul 25, 2019 12:15 am

Re: lewis structures

Postby Megan Vu 1J » Mon Oct 28, 2019 11:51 am

To determine what element goes into the center, it depends on the ionization energy, which is the energy needed to remove an electron from an atom (gas phase). The trend for ionization energy shows that it increases as you go right and up in the periodic table. Thus, to determine the center, you need to find the element in the molecule that is furtherest away from the top right. However, remember that H is never the center atom.

In 2B11, for part A, it should be C since it has the lowest ionization energy.

Posts: 102
Joined: Wed Sep 18, 2019 12:15 am

Re: lewis structures

Postby 005162902 » Mon Oct 28, 2019 12:01 pm

According to my notes the center of the Lewis structure is always the element with the lowest ionization energy. I am not 100% sure on the explanation as to why though.

Sean Cheah 1E
Posts: 105
Joined: Wed Sep 18, 2019 12:20 am

Re: lewis structures

Postby Sean Cheah 1E » Mon Oct 28, 2019 1:32 pm

While it is true that the atoms with the lowest ionization energies generally go in the center, this is not always the case. For example, I challenge anyone who does not already know the structure of HNO2 (nitrous acid) to draw its Lewis structure from scratch and compare that with its real structure (pretty easy to find online). You might be surprised by how the atoms are actually strung together in this particular case.

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