Lewis Structure Rules

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alex_4l
Posts: 82
Joined: Thu Sep 26, 2019 12:18 am

Lewis Structure Rules

Postby alex_4l » Sun Oct 27, 2019 9:24 pm

Here's some general rules for drawing Lewis Structures!
1) Write the correct skeletal structure for the molecule
-hydrogen atoms will always be terminal (outside)
-many molecules tend to be symmetrical
***the least electronegative atoms is ALWAYS the central atom
2) calculate the total number of electrons for the lewis structure
3) add a single bond between each atom/central atom (count how many)
4) if electrons are left, start with central atom, distribute electrons among atoms so there are as many octets as possible
5) if any atoms don't have 8 electrons, form a double or triple bonds as necessary by moving any line pairs of electrons

alex_4l
Posts: 82
Joined: Thu Sep 26, 2019 12:18 am

Re: Lewis Structure Rules

Postby alex_4l » Sun Oct 27, 2019 9:29 pm

Follow up, there's 2 things to make sure you check when drawing a Lewis Structure in order to make sure it's correct
1) looking back at total of electrons count to make sure the total has been presented in the structure
2) each atom must have 8 electrons (doesn't matter about single or multiple bond, all need to have 8 electrons surrounding them

Kayli Choy 2F
Posts: 90
Joined: Sat Aug 24, 2019 12:17 am

Re: Lewis Structure Rules

Postby Kayli Choy 2F » Tue Oct 29, 2019 11:11 am

Additionally, if your molecule has resonance and you are drawing Lewis structures for the resonant structures, calculate the formal charge of each atom in each resonant structure. The Lewis structure that has atoms with formal charges closest to zero represents the lowest energy arrangement.


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