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6A13(c): cations as lewis acids

Posted: Sun Jul 28, 2019 11:39 am
by Katherine Fitzgerald 1A
We are asked whether Ag+ is a Lewis acid or a lewis base.

I wanted to check my thought process on deciding that this was a Lewis acid, and test which conclusions can be generalized to other cations.

The electron configuration for Ag is {Kr}4d105s1. It will lose its electron from 5s to form {Kr}4d10 for Ag+. There is now an empty 5s orbital, which can be occupied by a lone pair, so it is an acid.

Is that right? Or is that the lone pair slotted into the empty f orbitals? If so , would that mean Ag could also act as an acid, rather than just Ag+?

If it is true that the loan pair from a lewis base would occupy 5s of the Ag+ cation, can we generalize and say that all cations act as Lewis acids? Or only for the heavier d-block elements? Are there any cations that can't act as Lewis acids?

Conversely, can all anions act as Lewis bases? If so, why (e.g., do they all have lone pairs)? Any that cna't?

Re: 6A13(c): cations as lewis acids

Posted: Sun Jul 28, 2019 7:43 pm
by Chem_Mod
It is a good general assumption for cations as acids and anions as bases, since depending on the charge would promote either the accepting or donating of electron pairs. Also, we do not cover the f block and heavy d metals as their is little biological application, so I don't believe that would be the case regarding your idea with the f block.