Electron Configuration
Methods for expressing electron locations:
1. Configuration
2. Orbital Notation
ELECTRON CONFIGURATION
• Electrons find homes in orbitals
• Electrons fill orbitals from lowest energy level
FIRST, to highest energy level, LAST.
• REMEMBER!
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s holds 2 – color the s blockORANGE
p holds 6 – color the p blockPURPLE
d holds 10 – color the d block GREEN
f holds 14 – color the f block BLUE
GRAB COLORS!
LET’S PRACTICE
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Let’s write the electron configuration for Mg.
What is the atomic number of Mg? _____ 12
How many electrons does Mg have? ______ 12
Write the electron configuration for Mg.
1s22s22p63s2
RULES
1. e- occupy orbitals of lowest energy first
2. orbitals hold up to two electrons of opposite
spin (clockwise – counterclockwise)
3. one e- enters each orbital until all orbitals have 1
e- with the same spin direction, THEN it’s paired
with e- with different spin
(LONERS FIRST  PARTNERS SECOND)
ORBITAL NOTATION
We can also use diagrams with arrows to show electrons
and their spin in a diagram called orbital notation. Each
block represents an orbital (like an electron parking spot).
1 atom of Li
# of P+ = 3
# of e- = 3


1 atom of F
# of P+ = 9
# of e- = 9
OCCUPY LOWEST ENERGY FIRST BEFORE
MOVING TO HIGHER ENERGY LEVEL
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OPPOSITE SPIN
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LONERS FIRST
PARTNERS SECOND
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
ORBITAL NOTATION
YOU TRY SULFUR!