Odd Lewis Structures

[katietietsworth_3c]

When doing an example like BF3 how will we be able to know that all of the F elements have an octet but B only has 6 electrons? Would this be something we might see on a test? I am just confused on how we can know which element to put the octets on when it comes to a compound like BF3 that has 24 electrons.

[Rian Montagh 2K]

I'm confused about this too but I believe in this case that since F is more electronegative, you could know that F would get the electrons.

[Sara Sadrolsadat 1G]

I read in a previous post that Dr. Lavelle had explained that Boron cannot have a full octet in this case because any double bonds would give fluorine a formal charge of 1-. Furthermore, the formal charge of Boron is zero (without having double bonds), even though it has 6 and not 8 electrons, because the element has 3 valence electrons and it is bonded to 3 fluorines. I believe this example may just be an exception to the octet rule. I'm not sure how we would know for certain that Boron not fulfilling an octet would be O.K., if we did not know the example though :/

[abbydouglas1K]

How do we account for electrons in the 3d orbital in our lewis structure ?