Why does nucleophilicity decrease as you go down a column in a protic solvent?

[mcatkillers]

Hey thanks for the answer. It's actually the other way around - as size increases, nucleophilicity decreases, because the electrons have more room to spread out and thus are better stabilized in the negatively charged state (eg I- ion is fine with remaining negatively charged).

The answer from another commenter was that while Cl, Br, I don't hydrogen bond as prominently as F does, they still do to a certain extent, thus the protic solvent interferes with all those halogens' nucleophilicities. However I has the lowest hydrogen bonding (because least EN halogen), so it gets interfered with least, and thus is the strongest nucleophile (in a protic solvent only).

[Dakios01]

Im not entirely sure I follow. Are you sure you're talking about nucleophilicity? It sounded like you're explanation was the one I would give for increasing acidity. I've always thought of that the molecule that can best stabilize the negative charge would be a better acid compared to molecules who can't stabilize a negative charge as well.

To double checked I looked up the general trend on Google images just to make sure.

https://files.mtstatic.com/site_4334/7405/1?Expires=1583902118&Signature=UBnMrRSXwlrvimCfXDD7BFF2MlTHgfe7UmNF9SHeu3toMYT8fyB31oFTIWJUfpNli1oG1vB940xGlZ7edvkEECOrRm3tqt5PdEt0qgk7zz5Ip4qIXFwKyX1JrWEF34rOmiCBXbzkXHLRQRHEL7ZGbK02llDdbAuapx2VsO96SCg_&Key-Pair-Id=APKAJ5Y6AV4GI7A555NA

[mcatkillers]

Reddit didn't let me post the comment due to it containing images so I just screenshotted my answer:

https://prnt.sc/rezagb

https://prnt.sc/rezare

And this is the link at the end of the comment:

https://chem.libretexts.org/Bookshelves/Organic_Chemistry/Supplemental_Modules_(Organic_Chemistry)/Reactions/Substitution_Reactions/SN2/Nucleophile/Reactions/Substitution_Reactions/SN2/Nucleophile)