Electron
Configuration
Activity
• Make three large sheets with a different element on each.
• Each sheet will have electron configuration, Bohr model with dots,
and orbital diagram of that element.
• Students will do a gallery walk and put sticky notes under three
categories; I know, I wonder, I discovered.
Electron Structure
n=4
n=3
n=2
n=1
Nucleus
Simple model of a potassium atom
More Energy
• In a neutral atom, electrons = atomic number.
• Electrons are arranged into energy levels.
• Energy Level (shell) defines how far the electron
is away from the nucleus.
Quantum Numbers
4 numbers that define the location and
movement of the electrons.
•
•
•
•
Principle Quantum number (n)
Orbital Angular Momentum Quantum number (l)
Magnetic Quantum number (ml)
Spin Quantum number (ms)
• Principle Quantum number (n) = Energy Level (shell)
defines how far the electron is away from the nucleus.
Orbitals
• Shells are divided into subshells (orbitals).
• Orbital Angular momentum quantum number (l) – defines
the shape of the sublevel (orbital).
– Four types: (named after spectroscopic groups of lines before
quantum mechanics)
•
•
•
•
•
Energy Level (shell)
s
(sharp)
p
(principal)
d
(diffuse)
f
(fundamental)
(angular momentum)
(l=0)
(l=1)
(l=2)
(l=3)
• Magnetic quantum number (ml) – defines the
orientation in space of the orbital.
s, p, d,
and f
orbitals
Electron Spin
• Spin Quantum number (ms) – designates direction of
electron spin.
• Each orbital can hold up to 2 electrons.
• Why only 2 in each orbital?
– Spin up
– Spin down
• Stern-Gerlach Experiment
Video
• Video – Electron Spin Explained
Electron Structure
• Shells and orbitals
–
–s
–p
–d
–f
l=0
l=1
l=2
l=3
n=1
1s
n=2
2s
2p
n=3
3s
3p
3d
n=4
4s
4p
4d
4f
Electron Structure
• Orbitals
– s / 1 orbital / 2 electrons
– p / 3 orbitals / 6 electrons
– d / 5 orbitals / 10 electrons
– f / 7 orbitals / 14 electrons
Electron Configurations
1st row 1s
2nd row 2s
3rd row 3s
4th row 4s
5th row 5s
6th row 6s
7th row 7s
1s
Row number – 1
3d
4d
5d
6d
6th row
4f
7th row
5f
Row number – 2
2p
3p
4p
5p
6p
7p
Electron Configurations
• What is the electron
configuration for H?
– H has 1 e-
1s1
• What is the electron
configuration for He?
– He has 2 e-
1s2
Electron Configurations
• What is the e- config.
for lithium?
1s2 2s1
• What is the e- config.
for oxygen?
1s2 2s2 2p4
Electron Configuration
Practice thru period 3
Board
Electron Structure
• Aufbau Principle – Electrons fill lowest
sublevels first.
– Aufbau = German for “building up”.
• Energy levels overlap.
• Expected order:
– 1s 2s 2p 3s 3p 3d 4s 4p 4d 4f...
• Actual order:
– 1s 2s 2p 3s 3p 4s 3d 4p 5s 4d 5p 6s 4f...
Aufbau Principle
4d
4p
3d
3p
3s
2p
2s
1s
4s
5p
5s
6p
6s
Increasing Energy
4f
5d
Electron Configurations
1st row 1s
2nd row 2s
3rd row 3s
4th row 4s
5th row 5s
6th row 6s
7th row 7s
1s
Row number – 1
3d
4d
5d
6d
6th row
4f
7th row
5f
Row number – 2
2p
3p
4p
5p
6p
7p
Electron Configuration
1s
2s
2p
3s
3p
3d
4s
4p
4d
4f
5s
5p
5d
5f
6s
6p
6d
7s
7p
Electron Configurations
• What is the e- config.
for iron?
1s2 2s2 2p6 3s2 3p6 4s2 3d6
• What is the e- config.
for iodine?
1s2 2s2 2p6 3s2 3p6 4s2 3d104p6 5s2 4d105p5
Electron Configuration
Practice after period 3
Board
Noble Gas Configuration
• Noble gases: Group 8A
– He, Ne, Ar, Kr, Rn, Xe, element 118
• e- configuration for Mg (element 12):
– 1s2 2s2 2p6 3s2
• e- configuration for Ne (element 10):
– 1s2 2s2 2p6
• Noble gas configuration for Mg:
– [Ne] 3s2
Noble Gas Configuration
• To write NGC:
– Find your element.
– Find the noble gas (Group 8A) before your
element.
– Write the noble gas in brackets.
– Add electrons to the noble gas until you reach
your element.
Noble Gas Configuration
• Write the NGC for bismuth (element 83)
– Previous noble gas: xenon (element 54)
– Bismuth is on row 6, so start with 6s2.
• Brings the total up to 56.
– Proceed to 4f14.
• Brings the total up to 70.
– Proceed to 5d10.
• Brings the total up to 80.
– Proceed to 6p3.
• Brings the total up to 83.
– Done!
[Xe] 6s2 4f14 5d10 6p3
Noble Gas Configuration
• Write the NGC for radium (element 88)
– Previous noble gas: radon (element 86)
– Radium is on row 7, so start with 7s2
• Brings the total up to 88.
– Done!
[Rn] 7s2
Noble Gas Configuration
Practice
Board
Configuration Practice
Sheet