We're going to say here that strong bases are bases that dissociate or ionize completely in water and have a high affinity for protons. That means they readily accept them; they want to accept H+ ions. Now weak bases, on the other hand, only partially dissociate and have a low affinity for protons and they favor reactants.

So here we have examples of a strong base and a weak base. Here we have NaOH, sodium hydroxide. It's a strong base, so when it's placed into water, it dissociates completely. The presence of all of these OH- ions, opposites attract. OH- is attracted to H+. And then we're making nothing but these ions, we make 100% of them. Products are highly favored.

On the other side, we have NH3 (ammonia), which is a weak base. It can accept H+ and become NH4+. It gets an H+ from water, water donating an H+ to it becomes OH-. But you don't make many of these ions. In fact, a vast majority of it is still in the form of ammonia. So it dissociates partially. We have a low affinity for H+ since there's not OH- being formed, and also because NH3 doesn't really accept an H+. And we have a majority of it still in NH3 form, so reactants are highly favored.

Now when it comes to strong acids and strong bases, here are some basic ones that you should keep in mind. For strong acids, they include HI, HBr, HCl (group 7A elements: iodine, bromine, and chlorine). When you combine these with H, they become strong acids. Their oxygen forms include bromate and perchlorate. When they combine with H+ they also make strong acids. Then, we have sulfuric acid, nitric acid, and the hydronium ion rounding it out as our strong acids.

For strong bases, it's easier to see the pattern; all of these are group 1A metals connected to OH-. So Li+ with OH- gives LiOH, K+ with OH- gives KOH. In group 2A, it involves calcium, strontium, and barium; when they combine with OH- they give a strong base. Keep this information in mind when looking at any questions dealing with acid or base strength.