 So, back to our dilemma. Arrhenius' definition that a base is something that produces hydroxide ions in water doesn't seem to work for ammonia. In 1923 the Danish chemist Johannes Bronsted and the English chemist Thomas Lowry independently came up with new definitions for acids and bases, and their definitions are more closely tied to how acids and bases react. They said, when an acid reacts it loses a hydrogen ion that is taken up by something else. You could say that acids are proton donors, although you have to remember that they're not doing it because they want to donate, it's just a chemical reaction. Bases on the other hand are substances that accept a hydrogen ion and bond to it. So, let's have a look at acids and bases again through this new perspective. When nitric acid dissolves in water it does dissociate into a hydrogen ion and a nitrate ion. But we can rewrite that to include our knowledge that the hydrogen ion is snapped up by a water molecule. So, now you can see that the nitric acid is donating a hydrogen ion to the water. That is, it's losing a hydrogen ion itself. Now let's look at ammonia. When ammonia is dissolved in water it doesn't remain as ammonia molecules. In fact it reacts with the water to produce ammonium hydroxide. So have a look at what happens. You can see that the ammonia accepts a hydrogen ion, a proton, from the water to become ammonium. This now leaves the water minus one of its hydrogens and so it becomes hydroxide. So here is the reason why ammonia had the properties of a base without having any hydroxide ions of its own. Because it behaves according to Bronsted and Lowry's definition as a proton acceptor, it takes a proton from water which leaves hydroxide ions left over. And so the solution is basic.