Boron and the octet rule  [ENDORSED]

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Katarina Ho -1B
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Joined: Fri Apr 06, 2018 11:03 am

Boron and the octet rule

Postby Katarina Ho -1B » Mon May 21, 2018 10:02 pm

Hi i'm confused because in class we went over an example of BF3 where Boron only had 6 valence electrons and not a full octet. Why is that okay?

Kuldeep Gill 1H
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Re: Boron and the octet rule

Postby Kuldeep Gill 1H » Mon May 21, 2018 10:33 pm

Hi from what I understand Boron does not follow the octet rule. in the case you stated BF3 if you think about it in terms of formal charges boron will have three shared with fluorine one for each of them and then if you were to calculate the formal charge of Boron you would see that it was 0. the same goes with fluorine. hope that helps!

Namie Fotion-1E
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Joined: Fri Apr 06, 2018 11:02 am

Re: Boron and the octet rule  [ENDORSED]

Postby Namie Fotion-1E » Mon May 21, 2018 11:08 pm

I noticed this too. It can be explained in a lecture by Professor Lavelle when he mentioned that group 13 elements, like B and Al, are exceptions to the octet rule and mostly have 6 electrons. He noted that these reactions are called "lewis acid-base reactions"

Katarina Ho -1B
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Joined: Fri Apr 06, 2018 11:03 am

Re: Boron and the octet rule

Postby Katarina Ho -1B » Mon May 28, 2018 11:06 pm

So does this mean that all atoms in the 13 group follow this anomaly or is it just boron and aluminum?

Yadira Flores 1G
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Re: Boron and the octet rule

Postby Yadira Flores 1G » Tue May 29, 2018 9:55 am

I think it's all the elements in group 13.

Ignacio Ramirez 1J
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Re: Boron and the octet rule

Postby Ignacio Ramirez 1J » Tue May 29, 2018 5:14 pm

The only atoms that are the exceptions of the octet rule are lithium, beryllium, boron, and Aluminum.

Steven Luong 1E
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Joined: Fri Apr 06, 2018 11:03 am

Re: Boron and the octet rule

Postby Steven Luong 1E » Wed Jun 06, 2018 10:48 pm

You should think of the octet rule as one of several rules of thumb that will help you predict the electronic structure of atoms and their behavior. Another such rule is that atoms are generally more stable when they possess little or no charge. In the case of boron, these rules make competing suggestions. The octet rule would suggest that boron might like to engage in four bonds and possess a negative charge; the neutral atom rule would suggest that three bonds and a neutral boron atom is best (I'm setting aside considerations of electronegativity...another rule of thumb).

The tension between these rules is actually helpful, since the truth is somewhere in between. In fact, boron typically engages in three bonds but is Lewis acidic. The boron in BH3 likes to take on some additional electron density if it is available (e.g., from a carbonyl group). This could (very roughly) be thought of as forming a weak forth bond. And the octet rule would lead us to expect this!

Paywand Baghal
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Re: Boron and the octet rule

Postby Paywand Baghal » Fri Jun 08, 2018 2:35 pm

Yadira Flores 1G wrote:I think it's all the elements in group 13.



I think the only exceptions are Lithium, Boron, Beryllium, and Aluminum.


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