Here, we're going to say that an amphoteric, also called an amphiprotic substance, is one that can act as an acid or base based on its environment. So, an acid, we're gonna say an acid here is a substance that donates or gives away an H+ ion, also referred to as a proton, when dissolved in a solution. A base, on the other hand, is a substance that accepts an H+ proton when dissolved in the solvent.
Now, we're gonna say many tetric species possess an H+ ion at the beginning of the compound and a negative charge at the end. So, this is a way of us spotting many types of amphoteric species. Now, a big exception to this is water, water is a prime example of an amphoteric species that doesn't exactly fit the description. If we take a look here, we have water behaving in two different reactions. In the first one, it acts as an acid when it reacts with the fluoride ion. Here, if it's acting as an acid, it's going to donate an H+ to F-. F- + H+ combine, they have opposite charges. So, they cancel out to give us HF. We lose an H+ from the water, so what's gonna be left behind is OH-.
Now, in another equation, we have the strong acid, hydrochloric acid. In this one, water will behave as a base and accept an H+ from the acid. Now, here to make things a little bit visually easier to see. So just imagine H+ going here and H+ went here. So, H+ went to the water. So, H+ left HCl. So what's left behind is Cl-. H+ is combining with the neutral water to give us H3O+. Now here, remember H3O+ represents the hydronium ion. Up to this point, we've been saying that H+ and H3O+ are very similar to each other, they're synonymous, interchangeable. So, when we're really saying H+, we're basically saying that H+ can be donated to any of the water molecules within our solution, thereby creating H3O+. That's why we kind of say that they can represent the same thing. So, water is a great example of an amphoteric species.
If we take a look at others, based on the description that we set up above, they all have a hydrogen at the beginning and they all have a negative charge. So, that's a good giveaway that the rest of these examples below represent amphoteric species. All right. So, keep that in mind, amphoteric species, based on what's around them, they can act as an acid or as a base. All right. So now that we've done this, click on to the next video and let's talk a little bit more about amphoteric species with an example problem.