Lewis Acids and Bases

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Drake_Everlove_1K
Posts: 19
Joined: Sat Sep 24, 2016 3:02 am

Lewis Acids and Bases

Postby Drake_Everlove_1K » Mon Oct 31, 2016 11:12 pm

Hi,

So I was wondering; if I have a compound with a central atom like Phosphorous, which can accept an expanded octet, how do I determine if it is a Lewis acid or base? If P has, say, 4 single bonds and a lone pair, would it like to donate that lone pair, making it a Lewis base?

If P has a formal charge of +1 and has 4 single bonds to other atoms, does it want another bond? Is it a Lewis acid by that definition>

Alex Dib 4H
Posts: 34
Joined: Wed Sep 21, 2016 2:57 pm

Re: Lewis Acids and Bases

Postby Alex Dib 4H » Tue Nov 01, 2016 1:04 am

Hi, I think this only applies to elements in group 13 because they have 3 valence electrons and don't complete a full octet, but will have 6 instead. An anion or terminal atom of a molecule can donate an electron pair to form a bond with that group 13 element, giving it an octet. The group 13 element that accepts the electron pair/bond is the acid, while the anion or atom that donates is the base.

Vincent Tse 2B
Posts: 30
Joined: Fri Jul 22, 2016 3:00 am
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Re: Lewis Acids and Bases

Postby Vincent Tse 2B » Tue Nov 01, 2016 4:06 pm

A lewis base is any species that donates an e- pair whereas a lewis acid is any species that accepts an e- pair.

You might want to refer to the examples given on pages 85-86 in the course reader as they relate this concept to coordinate covalent bonds.

Hope this helped!

Mimi_Giang_1F
Posts: 19
Joined: Wed Sep 21, 2016 2:56 pm

Re: Lewis Acids and Bases

Postby Mimi_Giang_1F » Wed Nov 02, 2016 12:37 pm

Is it that why in BCl3, the B is considered the Lewis acid (accepts 3 electrons from each of the Cl's to complete its shell of 6 electrons)?
I had previously thought that B would be considered the base, donating it's 3 outer electrons to each of the Cl's that only need one more electron to finish their octets.


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