cations of group 1 and 2

[Vicky Tong 3E]

During lecture, Professor Lavelle mentioned that Mg2+ and Ca2+ are the only cations in group 1 and 2 that form slightly acidic solutions despite the rest of the elements being too weak to do so. Is there a reason why these two specific elements are able to form acidic solutions?

[cecilia1F]

Hello,
I think that this was just a general example of the types of cations that would work. I believe that any element with that same charge would also work.

[Grace Chen 3F]

I think it is because these two cations are relatively smaller and has a higher charge compared to other cations in group 1 & group 2. Therefore, it has a stronger ability to attract lone pairs from the O of the H2O, and thus can be slightly acidic in water. However, Dr. Lavelle said that we can just assume all group 1 and 2 cations will not affect pH.