Double Bonds

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Jessica Tran_3K
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Joined: Thu Jul 25, 2019 12:17 am

Double Bonds

Postby Jessica Tran_3K » Fri Oct 25, 2019 12:02 pm

When drawing lewis structures, how do you know when to draw the double bond? and between which elements?

Kurtis Liang 3I
Posts: 50
Joined: Sat Aug 24, 2019 12:17 am

Re: Double Bonds

Postby Kurtis Liang 3I » Fri Oct 25, 2019 12:34 pm

If the formal charge on an atom is not equal to zero, that's a good indication that you will need a double bond at that location.

Jarrett Peyrefitte 2K
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Joined: Sat Aug 24, 2019 12:16 am

Re: Double Bonds

Postby Jarrett Peyrefitte 2K » Fri Oct 25, 2019 1:08 pm

To know when to use a double bond, you must find the formal charge by using the equation, FC = V - (L + S/2). When FC does not equal to 0, then you must use a double bond to make the FC equal to 0.

nehashetty_2G
Posts: 102
Joined: Thu Jul 25, 2019 12:15 am

Re: Double Bonds

Postby nehashetty_2G » Fri Oct 25, 2019 2:07 pm

Before considering formal charge, you usually use double bonds when you are trying to make every element satisfy the octet rule. So for example, if a compound has only 24 electrons and with your initial Lewis Structure with only single bonds you notice you are at 26 electrons, you would most likely use a double bond so the final electron count it 24 electrons.

You would then use formal charge to determine the best structure in case there are many potential options.

Maddie
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Joined: Wed Sep 11, 2019 12:17 am

Re: Double Bonds

Postby Maddie » Fri Oct 25, 2019 2:13 pm

you can tell by using the formal charge of an atom or reconfiguring the lewis structure if you do not have enough electrons to fully complete the lewis structure.

405268063
Posts: 102
Joined: Thu Jul 25, 2019 12:17 am

Re: Double Bonds

Postby 405268063 » Fri Oct 25, 2019 11:12 pm

I agree with the person before me who suggested using double bonds first when you are trying to satisfy the octet rule after you have figured out how many total electrons belong in that molecule. After that, you can use double bonds to make the FC equal to 0 for resonance structures.

Arianna Perea 3H
Posts: 50
Joined: Thu Jul 25, 2019 12:17 am

Re: Double Bonds

Postby Arianna Perea 3H » Sat Oct 26, 2019 9:22 pm

how do you know when to change a lone pair into a bonding pair?


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