Now, positive amines are acidic. So, let's think of some examples here. We could have NH₄Br, We could have CH₃NH₃Cl. We could have C₆H₅ NH₃NO₂, all different examples. What you should realize here is, you just have to think of it like this. You can say that this first compound could be an amine. But what's messing it up? That bromine is messing it up. That one element there signifies that we have a salt, so you should know to break it up into its ions. So this breaks up into NH₄⁺, this breaks up into Br^-. We have a positive amine, so therefore that amine is automatically acidic. So remember, just tell yourself, it could be an amine, it could fit either this description or this description, but there's something that's interfering with it. What's that one thing? It's usually going to be at the end and it's going to be a negative anion. So just break it up into its 2 ions. You'll have your positive amine, you'll have your negative ion, your anion. Look at the positive amine, it's automatically going to be acidic.

This too, this could be an amine, but what's messing it up? The chlorine at the end, so it's a salt, so break it up. We know it has to be plus 1 because the halogens are in group 7a and they're -one. And look, we just isolated another positive amine, therefore it's acidic, just like this one is acidic. Finally, the last one. We could say that this portion here could be our amine. But what's messing it up? NO₂. Remember, NO₂ is our nitrite ion. All those polyatomic ions you guys had to learn earlier on, you still have to remember them. Here, this is going to be C₆H₅ NH₃⁺. This is going to be NO₂^-. Again, let's not worry about the negative ions just yet. What's important for right now is that we have a positive amine isolated, so it's going to be acidic.

So remember, if we have a transition metal, it needs to be plus 2 or higher to be acidic. If it's not, it's neutral. For main group metals, metals in groups 1a, 2a, 3a and 4a, they have to be plus 3 or higher or they're going to be neutral. And for the main group metals, if you really think about it, since the main group metals have to be plus 3 or higher, that automatically means that group 1a, which are plus 1, and group 2a, which are always plus 2, will always be neutral. So they're not going to meet the requirement.

So if you see a SALT question on your exam and it has a group 1a or 2a metal involved, automatically that metal is going to be neutral because it's not going to meet the minimum requirement. Group 3a is plus 3, so if you see aluminum or gallium or something, those will be acidic. It gets a little tricky in group 4a. If you have a periodic table near you, just take a look at it. In group 4a, we have Tin, Sn, and then we have Lead. Now, they're in group 4a. But remember, I said this several videos ago that these two, even though they're main group metals, they can act like transition metals. They can be either plus 2 or plus 4. So be careful, which one are they giving you? If they're giving you Sn²⁺ or Pb²⁺, their main group metals, they don't meet the minimum requirement of plus 3. So they would be neutral. But if you have Sn⁴⁺ or Pb⁴⁺, then they would meet the minimum requirements and they would be acidic. That one's a little tricky, so remember that.