Transcript Electron Configuration Tutorials

Electron Configurations.
The purpose of this tutorial is to help you understand
how electrons are arranged in their energy levels.
You will learn how to write electron configurations,
and how these electron arrangements relate to the
shape and lay-out of the periodic table.
Because electrons are so important in chemistry, the
way in which they are arranged around the nucleus
plays a crucial role in determining the chemical
reactivity of all the elements.
First let’s review a little:
As we have learned, electrons exist in very specific energy levels.
And when these electrons absorb energy…
They get energized up to higher levels.
Actually, the jump to higher levels is not a gradual transition as was just shown.
It is a “quantum” jump, and looks more like this:
Quantum means it happens all at once – instantaneously – because the electron can
never exist between levels – not even for a second.
Once it is at this higher level (excited state), it doesn’t stay there long.
It quickly drops down to a lower level – again as a quantum leap – and as it does, it
gives off a distinct band of light energy.
Also, notice how the electron doesn’t have to drop all the way back down to the lowest
level. It can get energized up to any level, and from there it can drop to any lower level.
AND the different drops each produce different frequencies of light.
And
a
52 
dropdrop
produces
violet
light
See
how
an2electron
dropping
from
the
A
4
electron
produces
blue
light
3rd level to the 2nd level produced red light
7th
6th
5th
4th
3rd
2nd
Now let’s take a closer look at these electron
energy levels. We’ll color code them to make
them easier to distinguish...
We will see in a moment that these levels are
actually made up of sublevels. The higher up you
go, the more sublevels there are. We will represent
these sublevels as lines with boxes on them.
The boxes
represent the “orbitals” that make up
the sublevels. This is where the electrons hang out.
A maximum of two electrons can fit in any orbital.
The sublevel shown below is part of the 2nd level and
it is called the “2p sublevel.”
Note that the 2p sublevel is made up of 3 orbitals
(see the three boxes). And since two electrons can
fit in each orbital, the 2p sublevel is capable of
holding a maximum of six electrons:
2p
Also, let’s not forget about the nucleus… It is
positively charged (because of all the protons in it).
1st
After all, it is this positively charged nucleus that holds the
negatively charged electrons around it in the first place.
And with the 6th and 7th, it just gets worse and worse!
7th
7s
7g7h 7i
7f
7d
7p
6th
6g6h
6f
6d
6p
6s
5th
5g
5f
5d
5p
5s
4th
4d
4f
4s
4p
3rd
3p
3d
3s
2nd
2p
2s
1st
1s
The 5th level is just what you would expect:
Five sublevels: 5s (1), 5p (3), 5d (5), 5f (7) and 5g
(9). But look at how extensive the overlap becomes.
How about the 4th level? You should have a pretty
good idea about everything concerning it, accept
what the new letter is. Is this what you were thinking?
4s (1), 4p (3), 4d (5), and 4f (7). See how the number
of orbitals is always a consecutive odd number?
Also notice how the sublevels start to overlap.
The 4s is actually a little lower than the 3d. This
overlap is very important, and it becomes more
extensive as we move to higher levels.
Any guesses about the 3rd level?
The 3rd is made up of 3 sublevels [Do you see the
pattern?] The 3s sublevel (1 orbital), the 3p sublevel
(3 orbitals) and the 3d sublevel (5 orbitals)
The 2nd level is made up of 2 sublevels:
The 2s sublevel (which, like the 1s, contains just one
orbital), and the 2p sublevel which contains three
orbitals.
So let’s start at the bottom. The 1st energy level is
comprised of just one sublevel: It is called the 1s
sublevel, and it contains just one orbital. That’s it!
7th
6th
5th
4th
3rd
2nd
1st
7g
6h
7f
6g
5g
7d
6f
7p
6d
5f
7s
6p
5d
4f
6s
5p
4d
5s
4p
3d
4s
3p
3s
2p
2s
1s
Now, it may not look like it, but there is a
pattern to the levels shown at left, and the
order that they go in from lowest energy to
highest (1s, 2s, 2p, 3s, 3p, 4s, 3d, 4p, 5s…)
So let’s look at them again, but let’s spread
them out a bit horizontally, so they are not
so crowded.
10s
9s
8s
9p
8p
7p
8d
7d
6d
5f
4f
5p
5s
4d
4p
3d
4s
3p
3s
2p
1s
6f
5d
6s
2s
6g
5g
7s
6p
7f
This is the order in which
they were just introduced
to you…
There are plenty more, but
they go off the screen, so
we’re not going to worry
about them!
10s
9s
8s
9p
8p
7p
8d
7d
6d
6f
5f
5d
4f
6s
5p
5s
4d
4p
3d
4s
3p
3s
2p
2s
1s
6g
5g
7s
6p
7f
But check out this simple table
at right. If you draw diagonal
arrows starting at the bottom
like this…
It shows the precise order in
which the energy levels are
arranged from lowest to
highest!
10s 10p 10d
10f
10g 10h
9s
9p
9d
9f
9g
9h
8s
8p
8d
8f
8g
8h
7s
7p
7d
7f
7g
7h
6s
6p
6d
6f
6g
6h
5s
5p
5d
5f
5g
4s
4p
4d
4f
3s
3p
3d
2s
2p
1s
10s
9s
8s
9p
8p
7p
8d
7d
6d
6f
5f
5d
4f
6s
5p
5s
4d
4p
3d
4s
Watch …
3p
3s
2p
2s
6g
5g
7s
6p
7f
10s 10p 10d
10f
10g 10h
9s
9p
9d
9f
9g
9h
8s
8p
8d
8f
8g
8h
7s
7p
7d
7f
7g
7h
6s
6p
6d
6f
6g
6h
5s
5p
5d
5f
5g
4s
4p
4d
4f
3s
3p
3d
2s
2p
1s
1s
So what does all this have to do with chemistry?
Below is a rough sketch of the periodic table. For
the sake of this discussion, we are going to move
He over so it is in that little open space next to H:
And now we are going to number the periods 1
through 7:
As you will see, these periods
s
1
2
correspond (more or less) to the
1 H
energy levels we’ve just been
2
discussing.
3
1 2 3
And we are going to designate the
4
four distinct rectangular blocks by
5
the type of sublevel they match up
6
with: “s,” “p,” “d” and “f:”
7
And let’s also number the groups
1 2 3
within each block (1,2,3,4…)
p
1
2
3
4
d
4
5
6
4
5
6
f
7
8
9 10
7
8 9 10 11 12 13 14
Now let’s take the first ten sublevels (1s,
2s, 2p…) and see how the electrons filling
these sublevels takes us row by row across the periodic table, and
allows us to read electron configurations right off the table…
5
He
6
4d
5s
4p
3d
4s
s
1 2
3p
3s
2p
2s
1s
+
1
2
3
4
5
6
7
p
1
2
3
4
5
6
d
1
2
3
4
5
6
1
2
3
4
5
6
f
7
8
9 10
7
8 9 10 11 12 13 14
OK, so we’re going to use arrows pointing up or down to
represent the electrons. Can you guess into which box the first
electron would go given that it is attracted to the nucleus?
4d
5s
4p
3d
4s
s
1 2
3p
3s
2p
2s
1s
+
1s1
1
2
3
4
5
6
7
p
1
2
3
4
5
6
d
1
2
3
4
5
6
1
2
3
4
5
6
f
7
8
9 10
7
8 9 10 11 12 13 14
That’s right: it goes in the 1s sublevel. And its el. config is 1s2.
Notice in the table above where H is – in the area designated
as 1s. So where does the next electron go?
4d
5s
4p
3d
4s
s
1 2
3p
3s
2p
2s
1s
+
1s2
1
2
3
4
5
6
7
p
1
2
3
4
5
6
d
1
2
3
4
5
6
1
2
3
4
5
6
f
7
8
9 10
7
8 9 10 11 12 13 14
If you were thinking it went in the 2s, then you forgot that each
orbital can hold up to two electrons. Note how He is right here
in the area designated as 1s2 and so its el. config. is 1s2.
4d
5s
4p
3d
4s
s
1 2
3p
3s
2p
2s
1s
+
1s2
2s1
1
2
3
4
5
6
7
p
1
2
3
4
5
d
1
2
3
4
5
6
1
2
3
4
5
6
f
7
8
9 10
7
8 9 10 11 12 13 14
Now that the 1s is filled, the next electron goes in the
next sublevel – the 2s. Again note how Li is in 2s1.
Its full el. conf. is 1s2 2s1. What is Be’s el. conf?
6
4d
5s
4p
3d
4s
s
1 2
3p
3s
2p
2s
1s
+
1s2
2s2
1
2
3
4
5
6
7
p
1
2
3
4
5
6
d
1
2
3
4
5
6
1
2
3
4
5
6
f
7
8
9 10
7
8 9 10 11 12 13 14
Is this what you were thinking? Good. Now look at the
periodic table above, what comes after the 2s sublevel?
The 2p sublevel. So what will the next el. conf. be?
4d
5s
4p
3d
4s
s
1 2
1
2
3
4
5
6
7
3p
3s
2p
2s
1s
+
1s2
2s2
2p1
p
1
2
3
4
5
d
1
2
3
4
5
6
1
2
3
4
5
6
f
7
8
9 10
7
8 9 10 11 12 13 14
Is this what you were thinking? Notice how B is
in the 2p1 spot.
So its full el. conf. is 1s2 2s2 2p1. What’s next?
6
4d
5s
4p
3d
4s
s
1 2
1
2
3
4
5
6
7
3p
3s
2p
2s
1s
+
1s2
2s2
2p2
p
1
2
3
4
5
d
1
2
3
4
5
6
1
2
3
4
5
6
f
7
8
9 10
7
8 9 10 11 12 13 14
Is this what you were thinking? Notice how C is
in the 2p2 spot. So its el. conf. is 1s2 2s2 2p2
Notice also how when we fill a sublevel…
6
4d
5s
4p
3d
4s
s
1 2
1
2
3
4
5
6
7
3p
3s
2p
2s
1s
+
1s2
2s2
2p3
p
1
2
3
4
d
1
2
3
4
5
6
1
2
3
4
5
6
f
7
8
9 10
7
8 9 10 11 12 13 14
…we put one electron in each orbital until the
sublevel is half filled…
5
6
4d
5s
4p
3d
4s
s
1 2
1
2
3
4
5
6
7
3p
3s
2p
2s
1s
+
1s2
2s2
2p4
p
1
2
3
4
5
6
d
1
2
3
4
5
6
1
2
3
4
5
6
f
7
8
9 10
7
8 9 10 11 12 13 14
… and then we go back and start pairing off
This is called “Hund’s Rule, but it also referred to
as the bus seat rule. Can you figure out why?
4d
5s
4p
3d
4s
s
1 2
1
2
3
4
5
6
7
3p
3s
2p
2s
1s
+
1s2
2s2
2p5
p
1
2
3
4
5
6
d
1
2
3
4
5
6
1
2
3
4
5
6
f
7
8
9 10
7
8 9 10 11 12 13 14
Look at F. It’s just one electron away from having
filled 2p sublevel…
And it’s just one square away from the end of the 2p block.
4d
5s
4p
3d
4s
s
1 2
1
2
3
4
5
6
7
3p
3s
2p
2s
1s
+
1s2
2s2
2p6
p
1
2
3
4
5
d
1
2
3
4
5
6
1
2
3
4
5
6
f
7
8
9 10
7
8 9 10 11 12 13 14
And then Ne has a completely filled outer level.
Na is next. Can you guess where the next
electron is going to go?
6
4d
5s
4p
3d
4s
s
1 2
1
2
3
4
5
6
7
3p
3s
2p
2s
1s
+
1s2
2s2
2p6
3s1
p
1
2
3
4
5
6
d
1
2
3
4
5
6
1
2
3
4
5
6
f
7
8
9 10
7
8 9 10 11 12 13 14
That’s right: in the 3s sublevel. Right now,
write down in your notebook what you
think the next three el configs will be.
4d
5s
4p
3d
4s
s
1 2
1
2
3
4
5
6
7
3p
3s
2p
2s
1s
+
1s2
2s2
2p6
3s2
p
1
2
3
4
d
1
2
3
4
5
6
1
2
3
4
5
6
f
7
8
9 10
7
8 9 10 11 12 13 14
Did you get this one right?
5
6
4d
5s
4p
3d
4s
s
1 2
1
2
3
4
5
6
7
3p
3s
2p
2s
1s
+
1s2
2s2
2p6
3s2
p
1
2
3
4
5
d
1
2
3
4
5
6
1
2
3
4
5
6
3p1
f
7
8
9 10
7
8 9 10 11 12 13 14
How about Al’s? See how Al is
in the 3p1 spot on the per table
and its el config ends with 3p1
6
4d
5s
4p
3d
4s
s
1 2
1
2
3
4
5
6
7
3p
3s
2p
2s
1s
+
1s2
2s2
2p6
3s2
p
1
2
3
4
5
6
d
1
2
3
4
5
6
1
2
3
4
5
6
3p2
f
7
8
9 10
7
8 9 10 11 12 13 14
Now just advance through the
next 23 slides, but as you do,
make sure you are understanding
4d
5s
4p
3d
4s
s
1 2
1
2
3
4
5
6
7
3p
3s
2p
2s
1s
+
1s2
2s2
2p6
3s2
p
1
2
3
4
5
d
1
2
3
4
5
6
1
2
3
4
5
6
3p3
f
7
8
9 10
7
8 9 10 11 12 13 14
Exactly what is going on… how
the el configs simply follow the
sequence of the periodic table.
6
4d
5s
4p
3d
4s
s
1 2
3p
3s
2p
2s
1s
+
1
2
3
4
5
6
7
p
1
2
3
4
5
6
d
1
2
3
4
5
6
1
2
3
4
5
6
1s2 2s2 2p6 3s2 3p4
f
7
8
9 10
7
8 9 10 11 12 13 14
Your goal by the end of this slide
show is to be able to write el
configs for any element using just
the periodic table – and your brain!
4d
5s
4p
3d
4s
s
1 2
3p
3s
2p
2s
1s
+
1
2
3
4
5
6
7
p
1
2
3
4
d
1
2
3
4
5
6
1
2
3
4
5
6
1s2 2s2 2p6 3s2 3p5
f
7
8
9 10
7
8 9 10 11 12 13 14
5
6
4d
5s
4p
3d
4s
s
1 2
3p
3s
2p
2s
1s
+
1
2
3
4
5
6
7
p
1
2
3
4
d
1
2
3
4
5
6
1
2
3
4
5
6
1s2 2s2 2p6 3s2 3p6
f
7
8
9 10
7
8 9 10 11 12 13 14
5
6
4d
5s
4p
3d
4s
s
1 2
3p
3s
2p
2s
1s
+
1
2
3
4
5
6
7
p
1
2
3
4
d
1
2
3
4
5
6
1
2
3
4
5
6
1s2 2s2 2p6 3s2 3p6 4s1
f
7
8
9 10
7
8 9 10 11 12 13 14
5
6
4d
5s
4p
3d
4s
s
1 2
3p
3s
2p
2s
1s
+
1
2
3
4
5
6
7
p
1
2
3
4
d
1
2
3
4
5
6
1
2
3
4
5
6
1s2 2s2 2p6 3s2 3p6 4s2
f
7
8
9 10
7
8 9 10 11 12 13 14
5
6
4d
5s
4p
3d
4s
s
1 2
3p
3s
2p
2s
1s
+
1
2
3
4
5
6
7
p
1
2
3
4
d
1
2
3
4
5
6
1
2
3
4
5
6
f
7
8
7
8 9 10 11 12 13 14
1s2 2s2 2p6 3s2 3p6 4s2 3d1
9 10
5
6
4d
5s
4p
3d
4s
s
1 2
3p
3s
2p
2s
1s
+
1
2
3
4
5
6
7
p
1
2
3
4
d
1
2
3
4
5
6
1
2
3
4
5
6
f
7
8
7
8 9 10 11 12 13 14
1s2 2s2 2p6 3s2 3p6 4s2 3d2
9 10
5
6
4d
5s
4p
3d
4s
s
1 2
3p
3s
2p
2s
1s
+
1
2
3
4
5
6
7
p
1
2
3
4
d
1
2
3
4
5
6
1
2
3
4
5
6
f
7
8
7
8 9 10 11 12 13 14
1s2 2s2 2p6 3s2 3p6 4s2 3d3
9 10
5
6
4d
5s
4p
3d
4s
s
1 2
3p
3s
2p
2s
1s
+
1
2
3
4
5
6
7
p
1
2
3
4
d
1
2
3
4
5
6
1
2
3
4
5
6
f
7
8
7
8 9 10 11 12 13 14
1s2 2s2 2p6 3s2 3p6 4s2 3d4
9 10
5
6
4d
5s
4p
3d
4s
s
1 2
3p
3s
2p
2s
1s
+
1
2
3
4
5
6
7
p
1
2
3
4
d
1
2
3
4
5
6
1
2
3
4
5
6
f
7
8
7
8 9 10 11 12 13 14
1s2 2s2 2p6 3s2 3p6 4s2 3d5
9 10
5
6
4d
5s
4p
3d
4s
s
1 2
3p
3s
2p
2s
1s
+
1
2
3
4
5
6
7
p
1
2
3
4
d
1
2
3
4
5
6
1
2
3
4
5
6
f
7
8
7
8 9 10 11 12 13 14
1s2 2s2 2p6 3s2 3p6 4s2 3d6
9 10
5
6
4d
5s
4p
3d
4s
s
1 2
3p
3s
2p
2s
1s
+
1
2
3
4
5
6
7
p
1
2
3
4
d
1
2
3
4
5
6
1
2
3
4
5
6
f
7
8
7
8 9 10 11 12 13 14
1s2 2s2 2p6 3s2 3p6 4s2 3d7
9 10
5
6
4d
5s
4p
3d
4s
s
1 2
3p
3s
2p
2s
1s
+
1
2
3
4
5
6
7
p
1
2
3
4
d
1
2
3
4
5
6
1
2
3
4
5
6
f
7
8
7
8 9 10 11 12 13 14
1s2 2s2 2p6 3s2 3p6 4s2 3d8
9 10
5
6
4d
5s
4p
3d
4s
s
1 2
3p
3s
2p
2s
1s
+
1
2
3
4
5
6
7
p
1
2
3
4
d
1
2
3
4
5
6
1
2
3
4
5
6
f
7
8
7
8 9 10 11 12 13 14
1s2 2s2 2p6 3s2 3p6 4s2 3d9
9 10
5
6
4d
5s
4p
3d
4s
s
1 2
3p
3s
2p
2s
1s
+
1
2
3
4
5
6
7
p
1
2
3
4
d
1
2
3
4
5
6
1
2
3
4
5
6
f
7
8
9 10
7
8 9 10 11 12 13 14
1s2 2s2 2p6 3s2 3p6 4s2 3d10
5
6
4d
5s
4p
3d
4s
s
1 2
3p
3s
2p
2s
1s
+
1
2
3
4
5
6
7
p
1
2
3
4
d
1
2
3
4
5
6
1
2
3
4
5
6
f
7
8
9 10
7
8 9 10 11 12 13 14
1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p1
5
6
4d
5s
4p
3d
4s
s
1 2
3p
3s
2p
2s
1s
+
1
2
3
4
5
6
7
p
1
2
3
4
d
1
2
3
4
5
6
1
2
3
4
5
6
f
7
8
9 10
7
8 9 10 11 12 13 14
1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p2
5
6
4d
5s
4p
3d
4s
s
1 2
3p
3s
2p
2s
1s
+
1
2
3
4
5
6
7
p
1
2
3
4
d
1
2
3
4
5
6
1
2
3
4
5
6
f
7
8
9 10
7
8 9 10 11 12 13 14
1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p3
5
6
4d
5s
4p
3d
4s
s
1 2
3p
3s
2p
2s
1s
+
1
2
3
4
5
6
7
p
1
2
3
4
d
1
2
3
4
5
6
1
2
3
4
5
6
f
7
8
9 10
7
8 9 10 11 12 13 14
1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p4
5
6
4d
5s
4p
3d
4s
s
1 2
3p
3s
2p
2s
1s
+
1
2
3
4
5
6
7
p
1
2
3
4
d
1
2
3
4
5
6
1
2
3
4
5
6
f
7
8
9 10
7
8 9 10 11 12 13 14
1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p5
5
6
4d
5s
4p
3d
4s
s
1 2
3p
3s
2p
2s
1s
+
1
2
3
4
5
6
7
p
1
2
3
4
d
1
2
3
4
5
6
1
2
3
4
5
6
f
7
8
9 10
7
8 9 10 11 12 13 14
1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6
5
6
4d
5s
4p
3d
4s
s
1 2
3p
3s
2p
2s
1s
+
1
2
3
4
5
6
7
p
1
2
3
4
5
d
1
2
3
4
5
6
1
2
3
4
5
6
f
7
8
9 10
7
8 9 10 11 12 13 14
1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s1
6
So, the pattern for reading the electron configurations right off the periodic table
is
this:are wanting to write the electron configuration for any element, just follow
If you
this pattern and remember to stop at the element you’re representing.
1
1s2
2
2s2
2p6
3
3s2
3p6
4
4s2
3d10
4p6
5
5s2
4d10
5p6
6
6s2
5d10
6p6
7
7s2
6d10
4f14
5f14
For example, Cl (#17) which is right here on the table:
So the answer would be 1s2 2s2 2p6 3s2 3p5
The short cut would be: [Ne]3s2 3p5
1
1s2
2
2s2
2p6
3
3s2
3p5
4
5
6
7
Or how about Ni (#28)
1s2 2s2 2p6 3s2 3p6 4s2 3d8
Short cut: [Ar] 4s2 3d8
1
1s2
2
2s2
2p6
3
3s2
3p6
4
4s2
3d8
5
6
7
4f14
5f14
Let’s try Bi (#83)
1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s2 4d10
5p6 6s2 4f14 5d10 6p3 (don’t forget the 4f14!)
Short cut: [Xe]6s2 4f14 5d10 6p3
1
1s2
2
2s2
2p6
3
3s2
3p6
4
4s2
3d10
4p6
5
5s2
4d10
5p6
6
6s2
5d10
6p3
7
4f14
By the way, the orbitals are not really little empty boxes on
a line:
2p
Instead, they are specific three-dimensional shapes called
probability clouds that show where you are most likely to
find the electron around the nucleus.
The s sublevels are all spherical in shape:
And they just get larger and larger as you move to higher
levels
The p orbitals are a bit more complicated.
They are peanut shaped! And within the 2p sublevel, the
three orbitals are oriented at right angles to each other.
They are referred to as the 2px, 2py and 2pz orbitals.
And they fit together around the nucleus like this:
3s
2s
1s
Now try some of the problems from the Electron Configuartion worksheet.
The End