In general, removal of H⁺ from a species increases basicity, but trends stay the same, hence:
 

Consider the base strengths	N3–	>	O2-
	very strong		strong
	NH3	>	H2O
	weak base		very weak base

Like H₂O, NH₃ is capable of acting either as  an acid or as a base. NH₃ does not donate a proton to water; however, the species NH₄⁺ which has an additional H⁺ at N, is a weak acid.

 

In general, addition of H⁺ increases acidity.

Similarly H₃O⁺ is more acidic than water.

Again, while the protonated species both have increased acidity, their relative acidities are the same as those of the parent molecules H₂O and NH₃.