Quantum Mechanical Model
H
Hydrogen
has an
atomic #
of 1.
It has 1
valence
electron.
N
Nitrogen
has an
atomic #
of 7.
It has 5
valence
electrons.
Mg
Magnesium
has an atomic
# of 12.
It has 2
valence
electrons.
• The Quantum Mechanical Model depicts atoms
as mainly electrons surrounding a nucleus.
• The electrons, however, do not have a planetary
orbit as in Bohr’s model.
• The Bohr model has limitations because electrons
are too small and too fast to be able to pinpoint
exactly where they are and where they are going to
be next.
Vanadium has an
atomic # of 23.
When assigning
electrons to energy
levels there would be:
2 in the 1st level
V
8 in the 2nd level
8 in the 3rd level
2 in the 4th level
3 more in the 3rd level
Since there are 2 electrons in the
highest energy level, Vanadium
has 2 valence electrons.
Obviously, the Bohr model doesn’t
work well for Vanadium.
There are a maximum number of electrons that
go into each energy level:
• 2 electrons in the 1st energy level
• 8 electrons in the 2nd energy level
•18 electrons in the 3rd energy level*
•32 electrons in the 4th energy level…
Once there are 8 electrons in the 3rd energy level,
the 4th energy level begins to fill up.
Once there are 2 electrons in the 4th energy level,
the 3rd orbital fills until there are 18.
The Quantum Mechanical Model gives the location
of an electron as a probability instead of showing
it at a certain position.
These locations are called orbitals (energy levels).
For an electron to change energy levels (make a
quantum leap), it must gain or lose an exact
amount of energy.
Orbitals & Energy Levels
Each orbital is a cloud like region with a particular
shape. Each cloud shape is named with a letter.
–
–
–
–
–
s orbital spherical shape
p orbital perpendicular shape (dumbbell)
d orbital 5-dimensional
f orbital
g orbital
s orbital spherical shape
1 pair (2e-)
p orbital perpendicular shape (dumbbell) 3 pairs (6e-)
d orbital 5-dimensional
5 pairs (10e-)
f orbital
7 pairs (14e-)
g orbital
9 pairs (18e-)
• Nature likes order. Nature likes everything to be
in a stable, low-energy state when possible.
• Electrons fill low energy levels first, then the
higher energy levels.
Each energy level is made up of
1s2
orbitals. The first energy level has
2 2p6
2s
only one orbital. It can hold 2
3s2 3p6 3d10
electrons, because it is a s orbital.
The second energy level can hold
4s2 4p6 4d10 4f14
8 electrons: 2 in the s orbital & 6
5s2 5p6 5d10 5f14 5g18
in the p orbital.
6s2 6p6 6d10 6f14 6g18
The third energy level can hold
18 electrons: 2 in the s orbital, 6
7s2 7p6 7d10 7f14 7g18
in the p orbital & 10 in the d
HERE IS THE ORDER
orbital.
The fourth energy level can hold THAT THE ORBITALS
ARE FILLED
2 in the s orbital, 6 in the p orbital,
10 in the d orbital & 14 in the f orbital.
The fifth, sixth & seventh energy levels can hold 2 in the s orbital, 6 in
the p orbital, 10 in the d orbital,14 in the f orbital, &18 in the g orbital.
Electron Configuration & Energy Level Diagrams
• Electrons enter the orbitals of lowest energy first.
• An orbital may have 2 electrons at the most. They
must have opposite spins.
• Electrons enter the orbitals in parallel spins and
then the electrons traveling in the opposite
direction are added to each orbital.
Energy Level Diagram
for Rubidium
.
5s1
4p6
4s2
3d10
3p6
3s2
2p6
2s2
1s2
Rubidium
has 1
valence
electron.
37
Rb
1s2
2s2
3s2
4s2
5s2
6s2
7s2
2p6
3p6 3d10
4p6 4d10
5p6 5d10
6p6 6d10
7p6 7d10
We need to
see this
Aufbau
diagram
14
4f
to know
5f14 5g18 which
6f14 6g18 energy
7f14 7g18 levels to
fill first.
The electron configuration for
rubidium:
1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s1
Energy Level Diagram
for Aluminum
3p1
3s2
2p6
2s2
1s2
Aluminum
has 3
valence
electrons.
1s2
2s2
3s2
4s2
5s2
6s2
7s2
2p6
3p6 3d10
4p6 4d10
5p6 5d10
6p6 6d10
7p6 7d10
We need to
see this
diagram
to know
14
4f
which
5f14 5g18 energy
6f14 6g18 levels to
7f14 7g18 fill first.
The electron configuration:
1s2 2s2 2p6 3s2 3p1
Energy Level Diagram
for Arsenic
.
4p3
4s2
3d10
3p6
3s2
2s2
1s2
1s2
2s2
3s2
4s2
5s2
6s2
7s2
2p6
3p6 3d10
4p6 4d10
5p6 5d10
6p6 6d10
7p6 7d10
We need to
see this
diagram
to know
14
4f
which
5f14 5g18 energy
6f14 6g18 levels to
7f14 7g18 fill first.
2p6
The electron configuration:
Arsenic
has 5
valence
electrons.
1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p3