NH3 as a weak base

[Gabriel Wolf 3I]

Why does NH3 act as a weak base when it has a higher ionization energy than oxygen? Wouldn't the Nitrogen hold onto the electron pair more than the oxygen, meaning the Hydrogen would have less access to electrons if it bound to NH3? Wouldn't this be less favorable than the reactions that occur between hydrogen and oxygen in pure water?

[Fiona H 2E]

Ammonia doesn't contain any hydroxide ions to begin with, but when it's dissolved in water it acquires hydrogen ions from the water to produce hydroxide as well as ammonium ions. However, ammonia doesn't fully convert into hydroxide and ammonium ions in a solution, which is why it is considered a weak base.

[HemangD 3K]

You are right about how it's harder to take an electron away from nitrogen than to take an electron away from oxygen. However, I don't think this information plays a role in categorizing bases as weak or strong. From my understanding, a base is categorized as weak or strong depending on how much of it is able to dissociate in solution. Since ammonia only partially dissociates, it is categorized as a weak base. If it fully dissociated, then it would be categorized as a strong base.

[005502505]

When dissolved in water, ammonia acquires hydrogen ions from the water in order to make hydroxide. It doesn't fully convert these ions, however, leading to its categorization as a weak base. Hope this helps!!