Why do H and Li bond so differently with a hydroxide?

I am sure I am asking a very basic question but before coming here, I have made multiple attempts to find an answer elsewhere. Or maybe I am simply asking the wrong question, in some sense. If someone could nudge me in the right direction, I would be infinitely grateful to them. Here is what I am trying to understand:


A hydrogen cation added to a hydroxide ion forms water, which is neutral. A lithium cation added to a hydroxide forms LiOH, which is a strong base completely dissociating in a solution. Now, I understand why LiOH should be *more* alkaline than H2O. What I cannot understand is why it is *so much more* alkaline? Intuitively, one might expect a more gradual transition going from H to K. After all, H and Li are neighboring elements from the same group, with the same structure of the electron outer shell. Moreover, H in H2O is locked in a covalent bond whereas Li in LiOH is locked in an ionic bond. Ionic bonds are generally considered to be (much) stronger. Why is it not so in this case?




If I understand your question correctly, it sounds like you are interpreting one of the hydrogens in water as being similar to the alkali metals. In other words, you expect to see a similar change as in LiOH and KOH.


Well the reason you don't is because hydrogen is a non metal. It is significantly more electronegative than the alkali metals.


Therefore, H2O is not really hydrogen hydroxide. It's just water. Also, when water dissociates in water, it forms hydroxide ions but also protons. So, concentration of both is equal and pH is neutral. As a result, water is not alkaline.


Meanwhile, LiOH has a metal ionically bound to a covalently bound hydroxide ion. When it enters water, the strong hydrogen bonds rip apart the covalent bond between lithium and the hydroxide ion. The positively charged lithium ion is hydrated by water molecules with the oxygen end facing the lithium. And vice versa for hydroxide.


As you probably noticed, it does not dissociate into protons and a hydroxide ion. So it is alkali.


The reason hydrogen doesn't fit into the mould is because it is a non metal. And besides, the logic kinda breaks down since pH is a measure of how many protons are present relative to hydroxide ions.


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