Let's look at a particular family, we're going to start by looking at the Halogens.
So we're going to do the electron configuration of each of the Halogens,
let's begin with Fluorine, so we look at Fluorine,
what I want you to do is maybe pause the video and pull out a periodic table and.
Try to do the electron configuration of each of these as we go through it.
So you find the noble gas before fluorine, and work your way over to it.
And you come up with Helium 2s2 2p5.
Then we'll do it for Chlorine.
Okay, that'll be next.
Next to Halogen.
Well, if we do it's electron configuration the noble gas that comes before it,
is Neon.
So it's Neon 3s2 3p5.
And then we can do it for Bromine, and if we do it for Bromine the noble gas that
comes before Bromine is Argon, and we work our way over to the Bromine and
we have Argon 4s2 3d10 4p5.
So as we look down that family,
there we're going to see what they have in common.
And that is if you look at the highest principle quantum number n for these.
There's your n.
'Kay?
And you see how many electrons are in that with the highest n.
You see that there are 7 electrons located there.
And here we have an n that is 3 and if we look at all of those we have 7 electrons.
And if we look at Bromine,
while there is this d submerged in the middle between those s's and p's.
If we look at the highest n.
Okay?
Here.
We have again 2 plus 5.
We have 7 electrons.
In that value.
That highest in value.
So we see that all of these have something very much in common, for the Halogens.
If we look at a periodic table and
we find those Halogens, we will see a number associated above this family here,
that's the same as the number of electrons we saw in that.
So all of those will have that in common.
They will have seven electrons in that shell that.
That contains the highest in.
And this is going to be true for any one of these groups here.
Now, it only works for our representative elements.
We cannot do this, for any of the transition elements.
Okay, but it does work for those representative elements very, very nicely.