Intro to Electron Configuration
• Objective
– Today I will be able to:
• Calculate the electron configuration for elements on
the periodic table
• Evaluation/ Assessment
– Informal assessment – student responses when
reviewing electron configuration problems.
Listening to group interactions on practice sheets
and lab
– Formal Assessment – collecting and analyzing
responses to electron configuration worksheet 2
Lesson Sequence
• Warm – Up
• Explain: How to write electron
configurations
• Elaborate: write electron
configurations with a partner for
questions 1-18
• Evaluate: review the questions as
a class (informal assessment)
• Explain: electron configurations in
3d orbitals and Aufbau diagrams
• Elaborate: Students will complete
19-36 on electron configuration
WS with a partner
• Evaluate: review the questions as
a class (informal assessment)
• Explain: abbreviated electron
configurations
• Elaborate: Students will add a
column to the WS and repeat
write the abbreviated
configuration
• Evaluate: Abbreviated
configurations will be reviewed as
a class (informal assessment)
• Exit Ticket
Warm - Up
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What is an electron?
What is the abbreviation for an electron?
How does the mass of an electron
compare to the other subatomic
particles?
Do you believe in electrons?
How do we know electrons exists and how
they move and behave?
Objective
• Today I will be able to:
– Calculate the electron configuration for elements
on the periodic table
Homework
• Electron Configuration Practice
Agenda
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Warm – Up
Halloween Demos (as promised) 
Electron Configuration Notes
Electron Configuration Practice
Exit Ticket
Electron Configuration
Electron Configuration
• Electron configuration – arrangement of
electrons in an atom
• Electrons try to populate the lowest energy
levels available – “ground state”
Arrangement of Energy Levels
• Principal energy levels – represented by
n
• As atoms get bigger, there are more
electrons, therefore more energy levels
• Within each energy level, we have one
or more sublevels
• These sublevels are made up of orbitals
Orbitals
• According to modern atomic theory electrons
are found in orbitals
• Orbital – 3-D region around the nucleus
indicating the probable location of the
electron
• There are 4 types of orbitals where the
electrons can be found – s,p,d,f
• Order of energy from lowest to highest:
– s, p, d, f
Energy Sublevels
• Each sublevel occupies a specific location on
the periodic table:
Electron Configuration
n
1
2
3
4
5
6
7
p-block
s-block
d-block
n-1
f-block
n-2
Orbitals cont.
• Each sublevel can hold a specific amount of
electrons
– S=2
– P=6
– D=10
– F=14
Electron Configurations
• We can write the electron configurations for
each element (assuming the atom has a
neutral charge) representing the location of
the elements electrons in the energy levels
Examples
• Sodium (Na)
– Has 11 electrons (when neutral)
– Electron Configuration:
• 1s22s22p63s1
• Cobalt (Co)
– Has 27 electrons (when neutral)
– Electron Configuration
• 1s22s22p63s23p64s23d7
Electron Configuration Practice
Complete numbers 1-18
Why does 4s come before 3d?
• 3d is of slightly higher energy than 4s, but 4s is
further from the nucleus
• It takes less energy for a 3d electron to form pairs
then a 4s electron
Aufbau Diagram
• Instead of using the periodic table as a road
map, you can use the aufbau diagram to
determine the order that the electrons occupy
the different energy levels
• Electrons fill the lowest energy orbitals first
Aufbau Diagram
Complete Electron Configuration
Practice Worksheet 19 - 36
Abreviated Electron Configuration
• Scientists are lazy ;)
• We need a shorthand way to represent
electron configuration
• It would take a long time to write the
configuration for elements with a lot of
electrons
• How do we do this?
• Noble Gas Configuration
Noble Gas Configuration
• The last column on the periodic table is
referred to as the noble gases
• To write in abbreviated configuration:
– Find the last noble gas within the configuration
– Write the symbol
– Write the remaining configuration
• Example
• Ca - 1s2 2s2 2p6 3s2 3p6 4s2
• Noble Gas Configuration = [Ar] 4s2
Noble Gas Configuration
• Writing Noble Gas Configurations for ions is a
little bit different
• Must account for an electron being gained or
lost
– Chlorine Ion = Cl-1
• [Ne] 3s2 3p6
– Sodium Ion = Na+1
• [He] 2s2 2p6
Electron Configuration Practice
Go back and write the Abbreviated
(Noble Gas) configuration for the
elements on the worksheet on the right
hand margin
Exit Ticket
• Write the electron configuration of sulfur