Lewis Structures

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elizabethrojas1G
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Joined: Fri Sep 25, 2015 3:00 am

Lewis Structures

Postby elizabethrojas1G » Sat Oct 31, 2015 7:29 pm

For something like CH3COO- how do you know that the extra O is connected to C and not to O? Or if it ended in OH insted of OO how do you know the H would be connected to the C and not the O?

Andrea Sandri 3D
Posts: 21
Joined: Fri Sep 25, 2015 3:00 am

Re: Lewis Structures

Postby Andrea Sandri 3D » Sat Oct 31, 2015 9:51 pm

To determine that the second O is connected to the C and not to the other O, you would have to draw out the lewis structure of the CH3COO- molecule by the methods that have been discussed in lecture including the importance of finding the structure with the least formal charges, the tendency for carbon to form 4 bonds, the tendency for oxygen to form 2 separate single bonds or 1 double bond, etc. This information taken as a whole would lead to a lewis structure for CH3COO- where the second O is attached to C and not to the other O. If it was CH3COOH, the same strategy applies - one would have to utilize the rules and methods learned in lecture to determine the appropriate lewis structure. Only then could one see why the different atoms are connected as they are. Also, the formulas of organic compounds such as acetic acid in this case are arranged in such a way that makes the grouping easier to see. The fact that 3 H atoms follow the first C atom in the formula tells you that those 3 H atoms are bonded to the first C atom. Similarly, the fact that the 2 O atoms follow the second C atom tell you that those 2 O atoms will be bonded to the second C atom.


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