Now, for 2p, we'll see what happens when we
have to fill in 2p when we go lower down.
But before we do that, we've been talking
about the electron configuration.
How am I supposed to know what the electron
configuration of an element is?
The way we're able to do this is basically
in two ways, depending on what your professor
feels like teaching you.
One way, we're going to look at the periodic
table in a very different light.
We're accustomed to seeing the periodic table
with its elements and its atomic numbers and
its atomic masses.
In this image, we basically break down the
periodic table in this way.
We're going to look at it in this fashion
in order to write the electron configuration
of the element.
Just realize that the periodic table is separated
into different sections.
We're going to say Group 1A and 2A are what
we call the s-block.
Helium, which is over here, would be part
of that.
It would be grouped in together with it.
Remember, how many electrons can the s hold?
S can hold two electrons.
If we're talking about the s-block, we're
talking about two groups, Group 1 and Group
2.
Each group has a total of one electron it
can hold.
Down here in the pit, we call this our d-block.
Remember, how many electrons can the d-orbital
hold?
It can hold up to 10.
Look, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10.
Here, 3A to 8A, excluding helium, they're
called the p-block.
These are our p-block elements.
How many electrons can the p hold?
P orbital can hold up to 6 electrons, 1, 2,
3, 4, 5, 6.
Then, finally, down here with the lanthanides
and the actinides, these are our f-block.
F can hold up to 14.
So, if you count this you'll get 14 total.
The periodic table is basically arranged in
a way where this makes sense.
Also, what you should realize here is that
the periods, remember, this is period 1, period
2, all the way to period 7, the period number
reflects the shell number.
We have 7 periods as of now, so we have 7
shells as of now for our biggest elements.
We're going to say here that the period number
basically tells me the number of the orbital.
In period 2, we have 2s and 2p.
In period 3, we have 3s.
We also have 3d and we have 3p.
For period 4, we have 4s, 4d, 4p, and 4f.
If you add those up, that tells you the total
number of electrons within shell 3, shell
4.
What you should also realize here from this
trend is when we go from 4s, we drop down
one when we go to the d-block, so it would
drop down to 3d.
