Electron Configurations
You will need:
1. Your homework from Friday (Quantum Mechanical
Model in last week’s packet)
2. Your homework from last night (Electron
Configuration Guided Reading in this week’s packet)
Anything that you see in white, you should write down
Bohr Model of Hydrogen
Nucleus
e
e
Possible electron orbits
Zumdahl, Zumdahl, DeCoste, World of Chemistry 2002, page 331
Bohr Model of Hydrogen
• Bohr model = epic fail for all other elements
e
e
The Quantum Mechanical Model
The Quantum Mechanical Model
• 2 parts of an atoms
–Nucleus
–Electron cloud
»Where the probability of finding an
electron is high
»Drawn as a fuzzy cloud
»The cloud is more dense where the
probability of finding the electron is high.
Less likely
to find an
electron
Electron cloud
More likely
to find an
electron
Nucleus
The Quantum Mechanical Model
• Atomic Orbitals
–Space around the nucleus
–High probability of finding an
electron
–Has a specific energy level
–Has a specific sublevel
»Sublevels have different
shapes
• Further describes where an
electron is likely to be
found
The Quantum Mechanical Model
Atomic orbital shapes:
AKA: Angular momentum quantum number
S orbital
Angular momentum
quantum number (l) = 0
The Quantum Mechanical Model
Atomic orbital shapes:
P orbitals
Angular momentum quantum number (l) = 1
The Quantum Mechanical Model
Atomic orbital shapes:
D orbitals
Angular momentum quantum number (l) = 2
The Quantum Mechanical Model
Atomic orbital shapes:
F orbitals
Angular momentum quantum number (l) = 3
Think-Pair-Share
• Turn to your neighbor and…
–Explain what an orbital is
–List the 4 shapes of atomic orbitals
Vocabulary
• Quantum numbers: tell us the properties of
atomic orbitals and the properties of electrons
in the orbitals
• Principle quantum number
– Symbol: n
– The energy level that an electron occupies
• Angular momentum quantum number
– Symbol: l
– The shape of the orbital
• Spin quantum number
– +1/2 or -1/2
– Spin state of an electron
Main energy Sublevels
Number of orbitals Number of electrons
level (n)
(orbital shape) per sublevel
per sublevel
1
2
3
4
s
1
2
Main energy Sublevels
Number of orbitals Number of electrons
level (n)
(orbital shape) per sublevel
per sublevel
1
s
1
2
2
s
1
2
3
4
Main energy Sublevels
Number of orbitals Number of electrons
level (n)
(orbital shape) per sublevel
per sublevel
1
s
1
2
2
s
1
2
p
3
6
3
4
Main energy Sublevels
Number of orbitals Number of electrons
level (n)
(orbital shape) per sublevel
per sublevel
1
s
1
2
2
s
1
2
p
3
6
s
1
2
3
4
Main energy Sublevels
Number of orbitals Number of electrons
level (n)
(orbital shape) per sublevel
per sublevel
1
s
1
2
2
s
1
2
p
3
6
s
1
2
p
3
6
3
4
Main energy Sublevels
Number of orbitals Number of electrons
level (n)
(orbital shape) per sublevel
per sublevel
1
s
1
2
2
s
1
2
p
3
6
s
1
2
p
3
6
3
d
4
Main energy Sublevels
Number of orbitals Number of electrons
level (n)
(orbital shape) per sublevel
per sublevel
1
s
1
2
2
s
1
2
p
3
6
s
1
2
p
3
6
d
5
3
4
Main energy Sublevels
Number of orbitals Number of electrons
level (n)
(orbital shape) per sublevel
per sublevel
1
s
1
2
2
s
1
2
p
3
6
s
1
2
p
3
6
d
5
10
3
4
Main energy Sublevels
Number of orbitals Number of electrons
level (n)
(orbital shape) per sublevel
per sublevel
1
s
1
2
2
s
1
2
p
3
6
s
1
2
p
3
6
d
5
10
s
1
2
3
4
Main energy Sublevels
Number of orbitals Number of electrons
level (n)
(orbital shape) per sublevel
per sublevel
1
s
1
2
2
s
1
2
p
3
6
s
1
2
p
3
6
d
5
10
s
1
2
p
3
6
3
4
Main energy Sublevels
Number of orbitals Number of electrons
level (n)
(orbital shape) per sublevel
per sublevel
1
s
1
2
2
s
1
2
p
3
6
s
1
2
p
3
6
d
5
10
s
1
2
p
3
6
d
5
10
3
4
Main energy Sublevels
Number of orbitals Number of electrons
level (n)
(orbital shape) per sublevel
per sublevel
1
s
1
2
2
s
1
2
p
3
6
s
1
2
p
3
6
d
5
10
s
1
2
p
3
6
d
5
10
3
4
f
Main energy Sublevels
Number of orbitals Number of electrons
level (n)
(orbital shape) per sublevel
per sublevel
1
s
1
2
2
s
1
2
p
3
6
s
1
2
p
3
6
d
5
10
s
1
2
p
3
6
d
5
10
f
7
3
4
Main energy Sublevels
Number of orbitals Number of electrons
level (n)
(orbital shape) per sublevel
per sublevel
1
s
1
2
2
s
1
2
p
3
6
s
1
2
p
3
6
d
5
10
s
1
2
p
3
6
d
5
10
f
7
14
3
4
Electron Configurations
• Electron configuration:
– The arrangement of electrons in an atom
• The lowest-energy arrangement of the
electrons for each element is called the
element’s ground-state electron
configuration
Rules for writing electron configurations
• Aufbau principle:
– An electron occupies the orbital of lowestenergy first
1s
2s
3s
4s
5s
6s
2p
3p
4p
5p
6p
3d
4d 4f
5d 5f
6d 6f
Rules for writing electron configurations
• Hund’s rule:
– Electrons occupy equal energy orbitals one
at the time
– The electrons in each orbital have the
same spin
– School bus rule
2px
2py
2pz
Rules for writing electron configurations
• Pauli exclusion principle:
–Electrons in the same orbital must
have different spins
2px
2py
2pz
Think Pair Share
• Turn to your neighbor and explain the three
rules for electron configurations in your own
words
Orbital Diagram p. 105
Box = orbital
Up and down arrow =
electrons with opposite spins
Arrow = electron
Electron Notations
• Orbital notation
– Lines (or boxes) represent orbitals
– Arrows represent electrons
He
Writing Electron Configurations
1. Locate the element on the periodic table
Writing Electron Configurations
1. Locate the element on the periodic table
2. Determine the number of electrons in the element
Writing Electron Configurations
1. Locate the element on the periodic table
2. Determine the number of electrons in the element
3. Fill in the electrons in the orbital notation diagram starting
at 1s (remember the rules)
Writing Electron Configurations
1. Locate the element on the periodic table
2. Determine the number of electrons in the element
3. Fill in the electrons in the orbital notation diagram starting
at 1s (remember the rules)
4. Write the electron configuration from the completed orbital
notation diagram
Writing Electron Configurations
1. Locate the element on the periodic table
2. Determine the number of electrons in an atom of the
element
3. Fill in the electrons in the orbital notation diagram starting
at 1s (remember the rules)
4. Write the electron configuration from the completed orbital
notation diagram
5. Calculate the number of electrons in the electron configuration
and make sure it matches what you found in step 2
Orbital Notation
Li =
# of electrons = 3
Aufbau principle:
an electron
occupies the
orbital of lowestenergy first
Electron Notations
• Electron configurations
• Written in the following order:
1. Number of energy level
2. Letter of sublevel
3. Number of electrons in each sublevel written as
a superscript 2
Number of electrons
1s
Energy level
Sublevel
Energy levels
Sublevels
Number of electrons
2
2
6
1s 2s 2p
Electron Configurations
Li =1
Aufbau principle:
an electron
occupies the
orbital of lowestenergy first
Electron Configurations
Li =1s
Aufbau principle:
an electron
occupies the
orbital of lowestenergy first
Electron Configurations
Li =1s2
Aufbau principle:
an electron
occupies the
orbital of lowestenergy first
Electron Configurations
Li =1s22
Aufbau principle:
an electron
occupies the
orbital of lowestenergy first
Electron Configurations
Li =1s22s
Aufbau principle:
an electron
occupies the
orbital of lowestenergy first
Electron Configurations
Li =1s22s1
# of electrons = 3
Aufbau principle:
an electron
occupies the
orbital of lowestenergy first
Electron Configurations
# of electrons = 6
C=
Hund’s rule:
electrons occupy
equal energy
orbitals one at
the time with the
same spin
Electron Configurations
C=1
Hund’s rule:
electrons occupy
equal energy
orbitals one at
the time with the
same spin
Electron Configurations
C = 1s
Hund’s rule:
electrons occupy
equal energy
orbitals one at
the time with the
same spin
Electron Configurations
C = 1s2
Hund’s rule:
electrons occupy
equal energy
orbitals one at
the time with the
same spin
Electron Configurations
C = 1s22
Hund’s rule:
electrons occupy
equal energy
orbitals one at
the time with the
same spin
Electron Configurations
C = 1s22s
Hund’s rule:
electrons occupy
equal energy
orbitals one at
the time with the
same spin
Electron Configurations
C = 1s22s2
Hund’s rule:
electrons occupy
equal energy
orbitals one at
the time with the
same spin
Electron Configurations
C = 1s22s22
Hund’s rule:
electrons occupy
equal energy
orbitals one at
the time with the
same spin
Electron Configurations
C = 1s22s22p
Hund’s rule:
electrons occupy
equal energy
orbitals one at
the time with the
same spin
Electron Configurations
C
# of electrons = 6
= 1s22s22p2
Hund’s rule:
electrons occupy
equal energy
orbitals one at
the time with the
same spin
Electron Configurations
Pauli exclusion
principle:
electrons in the
same orbital must
have different
spins
Ca =
# of electrons = 20
Electron Configurations
Pauli exclusion
principle:
electrons in the
same orbital must
have different
spins
Ca = 1
Electron Configurations
Pauli exclusion
principle:
electrons in the
same orbital must
have different
spins
Ca = 1s
Electron Configurations
Pauli exclusion
principle:
electrons in the
same orbital must
have different
spins
Ca = 1s2
Electron Configurations
Pauli exclusion
principle:
electrons in the
same orbital must
have different
spins
Ca = 1s22
Electron Configurations
Pauli exclusion
principle:
electrons in the
same orbital must
have different
spins
Ca = 1s22s
Electron Configurations
Pauli exclusion
principle:
electrons in the
same orbital must
have different
spins
Ca = 1s22s2
Electron Configurations
Pauli exclusion
principle:
electrons in the
same orbital must
have different
spins
Ca = 1s22s22
Electron Configurations
Pauli exclusion
principle:
electrons in the
same orbital must
have different
spins
Ca = 1s22s22p
Electron Configurations
Pauli exclusion
principle:
electrons in the
same orbital must
have different
spins
Ca = 1s22s22p6
Electron Configurations
Pauli exclusion
principle:
electrons in the
same orbital must
have different
spins
Ca = 1s22s22p63
Electron Configurations
Pauli exclusion
principle:
electrons in the
same orbital must
have different
spins
Ca = 1s22s22p63s
Electron Configurations
Pauli exclusion
principle:
electrons in the
same orbital must
have different
spins
Ca = 1s22s22p63s2
Electron Configurations
Pauli exclusion
principle:
electrons in the
same orbital must
have different
spins
Ca = 1s22s22p63s23
Electron Configurations
Pauli exclusion
principle:
electrons in the
same orbital must
have different
spins
Ca = 1s22s22p63s23p
Electron Configurations
Pauli exclusion
principle:
electrons in the
same orbital must
have different
spins
Ca = 1s22s22p63s23p6
Electron Configurations
Pauli exclusion
principle:
electrons in the
same orbital must
have different
spins
Ca = 1s22s22p63s23p64
Electron Configurations
Pauli exclusion
principle:
electrons in the
same orbital must
have different
spins
Ca = 1s22s22p63s23p64s
Electron Configurations
Pauli exclusion
principle:
electrons in the
same orbital must
have different
spins
Ca = 1s22s22p63s23p64s2
# of electrons = 20
Electron Configurations
Cl =
# of electrons = 17
Electron Configurations
Cl = 1
Electron Configurations
Cl = 1s
Electron Configurations
Cl = 1s2
Electron Configurations
Cl = 1s22
Electron Configurations
Cl = 1s22s
Electron Configurations
Cl = 1s22s2
Electron Configurations
Cl = 1s22s22
Electron Configurations
Cl = 1s22s22p
Electron Configurations
Cl = 1s22s22p6
Electron Configurations
Cl = 1s22s22p63
Electron Configurations
Cl = 1s22s22p63s
Electron Configurations
Cl = 1s22s22p63s2
Electron Configurations
Cl = 1s22s22p63s23
Electron Configurations
Cl = 1s22s22p63s23p
Electron Configurations
Cl = 1s22s22p63s23p5
Exit Ticket
• Fill out the worksheet that is being passed
out
• Turn it in when you are finished
• Begin working on tonight’s homework
– Save #4 for tomorrow night
Blocks of the Periodic Table
s
1
2
3
4
5
6
7
p
1s
2s
f
2p
3s
d (n-1)
3p
4s
3d
4p
5s
4d
5p
6s
5d
6p
7s
6d
7p
6
(n-2) 7
4f
5f
1s
Electron Notations
• Noble gas notation
– The noble gas that comes before the desired
element on the periodic table is written in
brackets
– The rest of the electron configuration is written at
the end
• Energy level
Sodium’s noble gas notation:
• Sublevel
Number of electrons
1
Noble gas
[Ne]3s
• Number of electrons
Energy level
Sublevel
Electron Configurations
Fe = 1s
Electron Configurations
Fe = 1s2
Electron Configurations
Fe = 1s22
Electron Configurations
Fe = 1s22s
Electron Configurations
Fe = 1s22s2
Electron Configurations
Fe = 1s22s22
Electron Configurations
Fe = 1s22s22p
Electron Configurations
Fe = 1s22s22p6
Electron Configurations
Fe = 1s22s22p63
Electron Configurations
Fe = 1s22s22p63s
Electron Configurations
Fe = 1s22s22p63s2
Electron Configurations
Fe = 1s22s22p63s23
Electron Configurations
Fe = 1s22s22p63s23p
Electron Configurations
Fe = 1s22s22p63s23p6
Electron Configurations
Fe = 1s22s22p63s23p64
Electron Configurations
Fe = 1s22s22p63s23p64s
Electron Configurations
Fe = 1s22s22p63s23p64s2
Electron Configurations
Fe = 1s22s22p63s23p64s23
Electron Configurations
Fe = 1s22s22p63s23p64s23d
Electron Configurations
Pauli exclusion
principle:
electrons in the
same orbital must
have different
spins
Fe = 1s22s22p63s23p64s23d6