ELECTRON CONFIGURATION
2 Methods to use:
1. electron configurations (using Periodic Table Blocks)
2. orbital notations (arrows)
1. ELECTRON CONFIGURATION
Electrons find homes in orbitals and fill orbitals from lowest energy level FIRST, to
highest energy level, LAST.
REMEMBER!
- s holds 2 – color the s block yellow
- p holds 6 – color the p block green
- d holds 10 – color the d block red
- f holds 14 – color the f block blue
EX. Let’s write the electron configuration for Magnesium.
What is the atomic number of Mg? _____ How many electrons does Mg have? ______
Write the electron configuration for Mg.
Writing the address of electrons in atoms = Electron Configuration
3 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)
# of
Protons =
Element
#
Electrons
Orbital Filling
1s
2s
2p
2p
2p
3s
H
He
Li
Be
B
C
N
O
F
Ne
EX. What is the electron configuration of Silicon?
EX. What is the electron configuration of Lithium?
EX. What is the electron configuration of Sulfur?
TRICKS! 1. Valence electrons and the periodic table (by group #)
2. Divided by blocks
3. [Noble Gas] notation
Electron Configuration
2. 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).
Remember!
- s has 1 orbital – holds 2 e- p has 3 orbitals – holds 6 e- d has 5 orbitals – holds 10 e- f had 7 orbitals – holds 14 eEXAMPLES OF ORBITAL NOTATION
1 atom of Li
# of P =
# of e- =
1s
2s
1s
2s
1 atom of F
# of P =
# of e- =
2p
1 atom of S
# of P =
# of e- =
1s
2s
2p
http://www.chemfiles.com/flash/e_configs1.swf
3s
3p
Homework – Electron Configurations and Orbital Notation
NAME_______________
Write the electron configurations for the following elements.
1. N
2. Cl
3. Ne
4. V
5. Mg
Find the elements with the following configurations.
6. 1s22s2
7. 1s22s22p2
8. 1s22s22p63s2
Show the orbital notation (including orbital and spin of electron) for the following:
HINT: You may replace drawing a box by drawing an underline as I’ve demonstrated.
9. H
___
1s
___
2s
___ ___ ___ ___ ___ ___ ___
2p
3s 3p
10. Mg
11. C
12. O
Write out the electron configurations AND show the orbital notation for the following.
13. He
14. Be
15. F