00:01
Alright, so we're going to draw the lewislst structure for this compound right here, and we have to indicate formal charges and if there's any resonant structures.
00:11
And you know there's resonant structures where you can move a double bond and there's rotation of the molecule, so i'll show you what that means.
00:19
So let's write the equation for formal charge.
00:22
So for formal charge, we need number of valence electrons minus number of lone pair electrons or you can call it non -bonding electrons either works non -bunding electrons which are lone pair electrons minus bonds that's around that element or you can do one -half bonding electrons so there's different equations i like this one there's a little bit less math than this one so this is the one that i like to use but you can use the regular one, which is number of valent electrons minus lumpere electrons minus one half bonding electrons.
01:06
Alright, so before we start, the first thing you should notice is the order.
01:10
So hydrogen can never be in the center.
01:12
Usually the first element is in the center.
01:14
Hydrogen can't be in the center because hydrogen can only form one bond.
01:18
All right, and after i can't do anything else.
01:20
So carbon will be our center atom.
01:22
Surrounded by oxygen, oxygen, and hydrogen.
01:27
And what we're going to do now is we need a total number of electrons.
01:31
So we're going to add the number of valence electrons.
01:34
So i'm going to do hydrogen plus carbon, plus two oxygens, plus one extra electron.
01:42
That's what that negative means.
01:43
It means that we have an extra electron to use in here.
01:46
So hydrogen has one valence electron plus carbon has four, plus each oxygen, i have two of them, each of them has six, plus one.
01:56
That will give me 12, and then four, five, six.
02:00
So six plus 12, that will give me 18.
02:04
So now the first thing that i'm going to do is i'm going to connect everything to the center atom.
02:09
So one, two, three.
02:11
I have to use two, four, six electrons out of the 18.
02:14
So now i only have 12.
02:16
And then i'm going to balance from the outside in.
02:19
So you want everything to have eight electrons, around it except for hydrogen.
02:25
So i have 12.
02:26
I'm going to start one, two, three, four, five, six.
02:30
And the reason i know i need six is because i already has two.
02:33
I need a total of eight.
02:34
We already have two, so we need six more.
02:37
So i have six more.
02:39
One, two, three, four, six.
02:42
You have used all of them.
02:44
We can't add any more.
02:45
But if you notice, carbon is not stable.
02:47
Carbon has six, two, four, six.
02:49
It needs two more.
02:50
So what's going to happen is we're going to make a double one.
02:54
So i can take from either oxygen, it doesn't matter which oxygen you take, because at the end of the day we're going to draw both ways.
03:01
And i'm going to put it in brackets to indicate that it's a polyatomic ion, right? it had to take an electron from something else, so that's why we indicated.
03:11
And this is going to be a resonance structure, and a resonance structure is a structure in which the double button moves, right? it rotates.
03:20
So then it's going to look like this.
03:26
So it's just a rotation of the double one, right? so it still has the same distribution, and now we're going to calculate a formal charge.
03:37
So i'm going to do a different color.
03:40
So formal charge of each of them, so let's start with hydrogen.
03:47
Number of valence electrons is one minus non -bonding electrons.
03:51
It has none.
03:52
So zero, minus bonds.
03:54
It has one bond.
03:54
So four more charge of it is zero.
03:57
And it looks the same on both.
03:58
So that's zero.
04:00
Then for carbon, number of valence electron is four minus non -bonding electrons.
04:05
All of them are bonded, so zero.
04:07
Mine is bonds, one, two, three, four bonds.
04:10
Formal charged, it's zero.
04:13
And then we do single bond the oxygen.
04:17
So i'm going to do single bond oxygen, so i know which one's which.
04:20
So for this single bond that oxygen, i have six valence electrons, six non -bonding electrons, minus one bond and this will give me a negative one formal charge and then for the double bond the oxygen is six valence electrons minus four non -bonding electrons one two three four minus two bonds one two and that will give me a formal charge of zero and it should you should ideally so if they didn't have a charge then all of them should ideally be zero but this is a charge right therefore one of them should have a charge and it should be the more electric negative one.
05:02
And we have zero here and negative one here and zero here.
05:05
They look exactly the same.
05:07
You can do the same math, right? all i did was just rotate the double one.
05:13
Right, let's do b.
05:40
All right, so for b we have hco3 minus and how it works is carbon.
05:44
We'll go in metal.
05:45
Three oxenids around there.
05:47
And actually, the hydrogen does not actually belong to the carbon.
05:50
It belongs to the oxygen.
05:51
And this is a matter of getting comfortable with it but you should also can i consider you can play around with it but you will notice that there's uh this comes from h2 co3 which means that it lost the hydrogen and that means that the hydrogen came from another oxygen so it's just kind of a matter of getting comfortable with how assets work for a matter of drawing this one right um so the first thing we should do is count the tonal number of vaguelans electrons so we have h plus carbon plus three oxygens plus an extra electron given to us.
06:29
So hydrogen has a 1 plus carbon has 4 plus each oxygen has 6.
06:34
Valance electrons plus one extra 1 that we get from here.
06:39
3 times 6 is 18.
06:41
And then we have 2 that's 20 and 4 is 24.
06:45
All right, so we have 24 electrons to use.
06:47
We are going to connect.
06:49
So 2, 4, 6, 8.
06:52
So minus eight that we use.
06:54
Each line represents two electrons.
06:56
So that will give me 16.
07:02
So then i'm going to start from the outside and hydrogen is done so we're not going to touch it.
07:06
So one, two, three, four, five, six, seven, eight, nine, ten, eleven, twelve, thirteen, fourteen, fifteen, and sixteen.
07:15
We have used all of them.
07:17
Notice that hydrogen is stable, hydrogen is stable with two electrons share.
07:21
Oxygen has eight.
07:22
Oxygen has eight.
07:23
Oxygen has 8, carbon has 2, 4, 6, not stable.
07:27
So you need to draw a double 1.
07:29
So we're going to take from oxygen and draw a double 1 here.
07:38
So because the double 1 can rotate, we need resonance structure.
07:47
And then it will be h -o -c -o -o -o.
07:56
Now there is one more resonance structure, and i hope you notice it.
08:01
But that's not very stable.
08:02
We're going to calculate the formal charge for that one too.
08:06
And that one looks like this.
08:11
So it is, again, a rotation of the double one because technically you can share any two electrons, right? but formal charges would tell you which one would be the best.
08:23
So let's do, those two are very similar, so you just calculate it for one.
08:28
So let's do formal charges for this one.
08:31
So for hydrogen, you have one balanced electron, minus zero non -bonding electrons, minus one bond will equal formal charge of zero.
08:45
Then we do this oxygen right here.
08:49
Right, so i'm going to call it bond o bond.
08:52
So i know this one right here.
08:54
So six, valence electrons.
08:56
You can also number them if you would like, so you can do oxygen one, oxygen two, oxygen three.
09:02
So that's also another common way to do this, so we can do it that way too.
09:05
So let's do o1.
09:06
So it would be six valence electrons minus 1, 2, 3, 4, 4 non -bonding electrons minus 2 ones.
09:14
And that will give me a formal charge of 0.
09:18
And then we're going to do this oxygen 2, so 02, will be 6 valence electrons minus 2, 4, 6 non -bonding electrons minus 1 bond right here.
09:30
That will give me a negative 1.
09:32
And then 03, it would be 6 valence electrons minus 6.
09:39
To four, four non -bonding electrons, minus two bonds, formal charge of zero.
09:45
It means that this one, zero, zero, and then negative one, right? the only thing we rotated was those two.
09:53
And carbon, oh, i forgot carbon.
09:55
Carbon has four valence electrons, minus zero non -bonding electrons, minus four bonds with the formal charge of zero.
10:05
Now let's do this one right here.
10:07
So this one, the formal charges of this one, would be hydrogen, will be one minus, so one valance electron minus zero non -binding, minus one bond, zero.
10:21
Then we do, i'm going to call this again, o2, o3.
10:26
So we have o1, six valence electrons, minus two non -bonding electrons, minus three bonds.
10:35
That's a positive one.
10:38
Then we have carbon.
10:41
Oh, we should do o2.
10:42
Let's do that soon.
10:43
O2.
10:46
Six valence electrons minus six non -bonding electrons minus one bond this is negative one and those two look exactly the same so it's going to be negative one too and then we do carbon it's going to be four valence electrons minus zero non -bonding electrons minus four bonds this is going to be zero so notice that those most of them have formal charge of zero and there's something has a charge of negative one as issued because we have a charge on the molecule this one there's multiple charges right and oxygens have similar electronic activities even when they're i mean they should have the same but it kind of shifts around when it's attached to something else right but the oxygen should not be a positive one there is no way that the oxygen is more positive than the carbon of the hydrogen especially since it has a lone pair so and also you have way too many charges right we want as many of them to have formal charge of cr as possible.
11:48
So this is why this is not that stable and this is most likely what is bound to form.
11:52
This right here.
11:55
Let's go to the c.
12:13
All right, so for c we have fso3 minus.
12:17
So it's gonna be sulfur in the middle, oxygen, oxygen, oxygen, and fluorine...