Hey guys, here we go today our last lesson for this unit covalent compounds So what we've talked about within our covalent compounds We saw in our lewis dot structures is that we're going to be sharing electrons, right? So that's going to be our difference in our bonds here And so we focused on how that actually looks and how it works By drawing out our lewis dot structures What we're going to try to do to finish off our discussion is how we start to name those atoms These molecules but so again some key things happens only between a nonmetal and a nonmetal There's no charges here. So this isn't the same case where we get to do crisscross method and figuring things out There's got to be some other way for us to figure it out, right?
So ionic compounds are super simple because the charge is the charge, right? It's based on where it is in the periodic table. We crisscross we get a set formula every time no matter what between those two different elements Always the same makes naming for easy Makes it easy for naming as well covalent compounds not so trip much So what are we going to do well the trick is we have to know prefixes so covalent compounds can actually be really easy to name As well because what we're going to essentially do is we're going to name the first element which again is a nonmetal So typically are we have very similar the same?
central atoms almost always It tends to be either carbon silicon nitrogen or phosphorus Tends to be the most common ones we see but again it could be others But so we named the first nonmetal then what we do is we name the second nonmetal But we still change the ending to ide so that still follows suit like we do with ionic bonding The trick now though is we need to know how many of each element is actually there So what we're gonna do is we're gonna add prefixes to identify the actual number of each element. So we have to add prefix to the first element. We have to add a prefix to the second element.
A couple things. First, the first element, if there's only one, we don't need a prefix at that time. So that is something we don't actually need to worry about.
So it makes it really easy. We only have to add a prefix if there's more than one or if the second element always has to have a prefix. So we can look at our individual prefixes here.
We have our, we'll go up to 10 on our different names. Mono, di, tri, tetra, penta, hexa, hepta, octa, nana, and deca. Most of those are probably very familiar from geometry. You might have learned them before or have similar ways that we might remember.
Like mono, if you think about a monopoly, right? One owning a company. one person ruling a monarchy. Die is for two. That's actually for like dice, right?
Die is actually that there's two of them. Try, like tricycle, tripod makes it really easy. Tetra is four. And Tetra actually has a very strong connection. If you know the game Tetris, everything in Tetris was about this idea of four.
All the different game pieces had four blocks arranged in different ways. If you were able to try to knock out four lines at any one time. If you've never played Tetris and you have no idea what I'm talking about, go check it out.
It's a really old school game that's fun. The rest are mostly all directly from geometry and math where you might recognize it. So we just need to know those.
And again, the mono is the only one that we would see happening for the second element. We don't use mono for the first element. So just some examples in practicing now, because that's really all there is to naming covalent compounds. So if I have CBR4 here, so what we're going to do is we're going to name the first element, which is carbon.
Simple. Name the second element, change our ending. So that's still our bromine, which becomes bromide.
So very similar, we had an ionic bonding. Now we add prefixes. Well, for our first element, there's only one, so we get to ignore the prefix.
But for our second element, we need the four. So we get tetra so that we end up with carbon tetra bromide, right? So it's awesome It's super simple because it's cool.
You got carbon you got one of them tetra bromide for BRs CBR for so it's almost easier than ionic compounds because the name will tell you exactly How many of each element is bonding now the question of what why do we actually get the certain number in each bond? That's where Lewis dot structures come into play. And again, in some cases, they're very easy to see why that's the case.
In this particular example, carbon has four valence electrons. So it has the four different electrons that it can share. Bromine is part of the halogens. It needs, they have seven.
So they have the one unpaired. So each bromine needs to bond with one electron on carbon. And that's how we'd end up with our particular structure.
Now, that's not going to work always, but it does at least give us an understanding of why we get some of the structures that we do. Another example is if I went P4Cl10. Now, with this, it may not actually be a real compound. It can be.
It may not be. But the idea is we have this connection of where these things could start to bond together to give us these different possibilities. But what we're doing really is naming the compounds. So name our first element.
P is phosphorus. Our second element is chlorine. So we change it to chloride.
Then we have to add our prefixes. So here. Both elements have more than one.
Therefore, we're going to have a prefix for both elements. So we get four for our phosphorus, which is tetra. Our prefix for 10 is deca.
So what we end up with is tetraphosphorus deca chloride. So again, 4P, 10Cl, get our formula P4Cl10. So it really, again, hopefully not too bad. One more example just to clarify a few more things.
N2O5. So again... Name our first element, nitrogen.
Name our second element, oxygen, except we're going to change our N to IDE, so we get oxide. We have more than one for each element, so we're going to use our prefix for two, which is di. Prefix for five is penta, and so we get N2O5 with dinitrogen pentoxide.
Now, notice I said pentoxide, and that's because in this case, a lot of times when we have that extra vowel in there, So from pentaoxide, we'll a lot of times drop the A from the prefix so that it doesn't have like this weird extra step in there. Now, this really honestly, that is not a hard, fast rule. There are certain resources, if you look up, would keep the A.
Other resources drop the A. So it is not something where, again, you're going to see too often, but it is something to keep in mind. If we see it, we might want to drop it just in case.
But it really sort of just sounded out. Dynitrogen pentoxide versus dynitrogen pentoxide, right? Which one flows a little bit easier is kind of what we go for. But if you include the A, it's not wrong. It still goes for there.
But again, we just want to have sometimes if there is that double value with the A and the O or A and I, we might not always want it. So that's our notes for today. Should be easy. Thanks, guys.
See you next time.