Electron Configuration Part 2
Intro- answer the following questions concerning Potassium (K)
1. How many valence electrons does it have?
2. Do a sketch of its atom (Bohr model) showing the electron
shells
Wave (Quantum) Mechanical Model of
the Atom

The electron does not have an exact
orbit around the nucleus (like Bohr’s
model).
-atomic orbital is where
an electron is 90% likely to
be found.
Electron configuration
Describes the location of electrons in an
atom
 Composed of energy levels, sublevels,
and electrons
 Looks like…

For Titanium (Ti): 1s22s22p63s23p64s23d2
Energy level
Its the same number as the period
 The bigger the energy level, the further
the electrons are from the nucleus, and
the more energy they have.

Sublevels
Each orbital can only hold 2 electrons (pauli
exclusion principle), so each sublevel has a different
number of orbitals

sublevel
s
p
d
f
# orbitals
Total # electrons
Shapes of orbitals
 There
is 1 spherical shaped s orbital, so
the s sublevel can hold 2 electrons.
There are 3 dumbbell shaped p orbitals
so p sublevel can hold 6 electrons

There are 5 d orbitals so 10 electrons can fit in
the d sublevel

There are 7 f orbitals so 14 electrons can fit in
the f sublevel)


AUFBAU PRINCIPLE- each electron will occupy the
LOWEST energy level available
So they fill orbital in a certain order…
- Notice the
number of
electrons that fit
in a sublevel
relates to the
block!
- color the
blocks different
colors to see the
difference!


AUFBAU PRINCIPLE- each electron will occupy the
LOWEST energy level available
So they fill orbital in a certain order…
- notice the d block
is one energy level
behind
- notice the f block
is 2 energy levels
behind
- follow the arrows
until you get to
your element
Using the chart on the last page and your periodic table answer
the following questions…
1. How many electrons can be placed in the 2s sublevel?
2. How many electrons can be placed in the 3d sub?
3. A total of eighteen electrons can be placed into the 3rd
energy level. Explain WHY.
4. A total of 32 electrons can be placed into the 4th energy
level. Explain WHY.
Electron Configuration notation
-
-
This method designates the principle energy
level, the sublevel, and the number of electrons
in each sublevel.
For example Fluorine:
-
1s22s22p5
Determine the element for each electron configuration in the table:
Electron configuration
1s22s1
1s22s22p3
1s22s22p63s23p5
1s22s22p63s23p64s23d6
1s22s22p63s23p64s23d104p2
1s22s22p63s23p64s23d104p65s24d105p4
1s22s22p63s23p64s23d104p65s24d105p66s25d14f9
1s22s22p63s23p64s23d104p65s24d105p66s24f145d106p67s25f3
Element
Refer to the following electron configuration and
answer the questions below: 1s22s22p63s23p64s23d5
a. How many total electrons does this element have?
b. What element is this?
c. How many energy levels are represented?
d. How many sublevels are represented?
Write the electron configuration for each element:
Mg:
Au:
Mg
1s22s22p63s2
Au
1s22s22p63s23p64s23d104p65s24d105p66s2 4f145d9
PAULI EXCLUSION PRINCIPLE- Because
electrons spin, two can occupy one orbital as
long as they are spinning oppositely.
HUND’S RULE- within a certain sublevel,
single electrons are placed one at a time in
orbitals with spins of the same direction,
and then will double up with electrons
spinning the opposite direction.
Example of Carbon
(6 electrons)
Electron configuration for Orbital Box diagrams:
- Each arrow represents an electron
 Ex. Oxygen
Atomic number = 8, so 8 electrons.
Start with s, then fill up orbitals as you go.
↑↓ ↑↓ ↑↓ ↑ ↑
1s 2s 2px 2py 2pz
Fill in the box
diagram for Fluorine
1s 2s 2px 2py 2pz
Draw a box diagram for each of these elements:
1.
He
2.
N
3.
Na
4.
P
Shorthand electron configuration
You can use the noble gases to help make
electron configuration easier to do.
 First identify the noble gas (Group 8A) that is
right BEFORE the element.
 Write that noble gas symbol in [brackets]
 Then write the rest of the configuration.
 Ex. Na: 1s22s22p63s1 or [Ne]3s1

examples: shorthand electron configuration
1. Mg
[Ne]3s2
2. Al
[Ne]3s2 3p1
3. Sn
[Kr] 5s24d105p2
4. Br
[Ar] 4s23d104p5
5. Po
[Xe]6s24f145d106p4