00:01
We want to calculate the formal charge for each of the atoms shown in red.
00:05
So let's go ahead and start with a.
00:08
So they do give us a formula, but i think the formula is just too much to kind of remember.
00:14
So i'll kind of show you all how i do these.
00:17
So first let's actually kind of draw this out a little bit more for a.
00:22
So we have this oxygen here.
00:24
It has the lone pair.
00:25
It's bonded to this boron.
00:28
And then the boron is going to have four things attached to it.
00:32
So f, f, and f.
00:35
And then we have two methyl groups attached to this oxygen over here.
00:41
So we have this.
00:44
All right.
00:45
Now, the way i like to do it is i like to draw the valent shell that i say in quotes because it's not truly the valent shell, but that's just how i like to think about it.
00:55
Around the atom, i'm trying to find the formal charge for.
00:57
So since these are covalent bonds, coming out, each of them are going to have at least one electron that is owned by the oxygen, since all of the covalent bonds should have two electrons, but if they're sharing, it should be an equal sharing, so each should get one.
01:14
So this oxygen here has five electrons, but it normally has six.
01:22
So it lost an electron.
01:25
So that means this oxygen here is going to have a positive charge on it.
01:31
So it's going to have a formal charge of one.
01:35
And then what about our boron over here? well, we can go through and do the same thing.
01:40
So we draw the little electron shell around it.
01:44
Each bond is going to donate one electron to this boron.
01:49
Boron normally has three electrons, but it has four.
01:54
So that means it has one more than what it normally has.
01:57
Means this is going to have a negative charge or a negative 1 formal charge.
02:03
Alright.
02:04
Now let's go ahead and do the same thing over here for b.
02:09
So the only thing i really need to draw out is i need to draw these two hydrogens attached to this.
02:18
So again let's go ahead and draw the valent shell going around the carbon.
02:25
So each of the bonds is going to donate one.
02:27
Now within the shell this carbon has five electrons but it normally has four.
02:33
So it has one more than what it normally has.
02:36
So that means it would be negatively charged.
02:40
Then this nitrogen here.
02:43
So let's draw the shell going around it as well.
02:47
Let me draw a little bit better.
02:51
So each of those bonds is going to donate one since they're sharing.
02:55
So this nitrogen has four electrons in its valence.
02:59
And that is going to mean that it has one less than what it normally.
03:03
Has because it normally has five electrons.
03:06
So that means this is going to have a positive charge on it.
03:11
And then we come out to this last one here, and we do the same thing.
03:17
So each of those bonds there is going to donate one electron to that nitrogen.
03:21
So it's going to have five electrons in total.
03:24
It normally has five, so this has a formal charge of just zero.
03:27
Well, it would be neutrally charged.
03:30
Now we can go ahead and move on to c here.
03:34
So let's draw these hydrogens out just like before.
03:40
And so this carbon here, so each of the bonds, once again, is going to donate one electron to that carbon.
03:48
So this carbon is going to have four in its valence...