[jj940901]

I learned that acidity generally increases as you move down a group in the periodic table, but then I saw this image which made me question that idea. If this was true, how come H-I is more acidic than H-Br? Also, someone mentioned that smaller atoms are better Lewis acids, but I'm not sure if I'm mixing up the concepts of Lewis acids and acidity. Could someone clarify these ideas for me?

[Borek]

I learned that acidity generally increases as you move down a group in the periodic table, but then I saw this image which made me question that idea. If this was true, how come H-I is more acidic than H-Br?

I is down the group from Br, isn't it?

But in general such rules are highly simplified and their applicability is limited, don't treat them too seriously. You can't directly compare acidity of organic acids with acidity of hydrides, these are way too different cases.

[jj940901]

Thank you. And yes you are right. I got confused in the case of HI and HBr. I guess I was confused with the acidity of a single atom such as F- vs I-, which makes I- more acidic due to its stability.