00:01
All right, in this question, we are going over a number of special cases for the act touch rule and a few tricky situations to talk about.
00:09
So first up, we have xef2.
00:13
Now, we know that xenon is a noble gas.
00:19
It already has its eight electrons.
00:22
And we also know that fluorine is in group 7 .8.
00:26
It's got seven electrons, but that doesn't really matter in this case.
00:29
We know that xenon already has eight, and therefore, if we form a bond, that xenon is going to have more than eight electrons.
00:40
So it's impossible for every atom in this compound to satisfy the octet rule.
00:51
Xenon is an exception to the octet rule.
00:54
So if we look at the lewis structure of xenon, we start with its eight electrons.
00:59
And then we have to add the fluorines to it, and the fluorines each have seven electrons.
01:07
And the only way that these would bond is by one bond with the xenon to each of the fluorines.
01:16
That means that this xenon will have 2, 4, 6, 8, 10 electrons that has access to.
01:28
And these fluorines will have 2, 4, 6, 8.
01:32
So the fluorins will satisfy the octet rule.
01:35
The xenon will have 10 electrons, which is an exception to the octet rule.
01:43
And i'll just draw the xenon a little bit more clearly.
01:50
So it'll look like this.
01:55
In theory, the fluorines will be on opposite sides, but it's easier to show the pairs this way.
02:02
Okay.
02:03
Next up, we have whether or not, i think it's, okay, so sf4 versus of4.
02:25
So sf4 will look like, well, let's, sulfur has six electrons that it starts with, and it will bond to 4.
02:45
Sulfurs.
02:47
Let's do it like this.
02:55
And i'm just going to move one of these electrons so it's easier to see.
03:13
Okay.
03:14
So when the sulfur is bonded to the four fluorines, the sulfur has a total of 10 electrons that it has access to, right? because it's got two here, two here, two here, two here, two here, and two here.
03:40
And this is in violation of the octet rule because, well, sulfur has 10 electrons.
03:49
So the question is, can oxygen do the same thing? and the answer is no.
03:55
And why? so remember that everything in row two can only have eight electrons in its valent shell.
04:08
It cannot go more than that.
04:09
Row 3 and above can.
04:14
And the reason why is because sulfur has access to a d orbital.
04:19
Actually, anything row 3 or higher has access to a d orbital.
04:28
That's where the extra electrons are going.
04:33
Because if we look at oxygen, for example, oxygen has a 1s orbital, a 2s orbital, and 3p orbitals for a total of 6 electrons.
04:53
And so there's no more, there are no more spaces to put extra electrons.
05:07
Okay, next up we have no plus versus no minus.
05:17
So to determine which bond between the nitrogen oxygen is stronger, we have to draw out the loose dot structures.
05:26
So nitrogen has five valence electrons and oxygen has six valence electrons and it has a positive charge here so we're going to subtract one.
05:37
That means we have 10 electrons to work with total.
05:41
So if we put nitrogen, oxygen, let's try drawing three bonds and adding the two electrons here.
06:00
Okay.
06:03
So we've got two electrons here, six electrons here.
06:08
So that's eight, and then two more, so that's ten.
06:12
So that uses up our ten electrons.
06:15
This nitrogen has eight electrons, and this oxygen has eight electrons.
06:21
Okay.
06:22
So i believe this is the correct glue of structure...