Lewis Structures

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Lewis Structures

Postby aaronharouni » Wed Oct 31, 2018 12:27 am

Why does the B in BF3 only have 6 electrons in its Lewis structure?

Brian Cook
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Re: Lewis Structures

Postby Brian Cook » Wed Oct 31, 2018 12:38 am

Boron doesn't need a full octet because it's in the 13th column, and elements there have stable electron states already.

megan blatt 2B
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Re: Lewis Structures

Postby megan blatt 2B » Wed Oct 31, 2018 6:41 pm

Boron is an exception to the octet rule. This occurs because a coordinate covalent bond is formed. In coordinate covalent bonds, one of the two atoms involved in the bond provides both of the shared electrons as opposed to each atom involved in the bond providing one electron. Additionally, if you were to calculate Boron's formal charge in a molecule like BF3, it would equal zero. Therefore, you know that even without an octet, Boron is stable in this molecule.

Manya Bali 4E
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Re: Lewis Structures

Postby Manya Bali 4E » Wed Oct 31, 2018 6:42 pm

What's already been said is true, but I also wanted to add that it's possible for B (boron) to complete its octet if another atom provides two electrons in what's called a coordinate covalent bond. To reiterate the example from today's lecture, BF3 + F^- --> BF4^-. In the product, B forms an octet due to the two electrons given by F^- (remember that F^- has 8 valence electrons).

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Re: Lewis Structures

Postby Javier_Ochoa_DIS_3J » Thu Nov 01, 2018 4:43 pm

Any element in the 13th column does not need to have a full octet. This would include B, Al, Ga, In, Ti, and Nh.

However they are allowed to have 8 if the compound needs it.

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