Orbital Notations and Electron
Configurations
1
N
= principle energy level
2
2N
2
= # of
e
in N
Finding Orbital Quantum #s on the
Periodic Table
S Block
1
2
3
4
5
6
7
3
4
5
6
4
5
D Block
F Block
1
2
3
4
5
6
7
P Block
Orbital Notation
 Shows
all four quantum numbers for
every electron in the atom.
 A box or line is one orbital.
 An arrow is one electron.
 Spin is designated as “up” or “down”.
Orbital Notation for Silicon

Silicon has 14 electrons, so you will draw 14 arrows.
1s
2s
3s
2p
3p
More Examples:
Magnesium
1s
2s
3s
2p
Copper
1s
2s
Chlorine
2p
1s
3s
2s
3p
2p
4s
3s
3d
3p
Electron Configurations
Shorthand versions of orbital notations.
 Does not indicate the magnetic or spin
quantum numbers.
 Tells the total number of electrons in each SET
of orbitals.

7
Writing an Electron Configuration
 Write
Neon.
the electron configuration for
2
2
6
1s 2s 2p
Principle Quantum Number
Orbital Quantum Number
Total Number of Electrons
8
Your Turn
 Write
the electron configuration for
Potassium.
 Write the electron configuration for
Copper
 Write the electron configuration for
Bromine
9
Answers

Potassium
1s22s22p63s23p64s1

Copper
2
2
6
2
6
2
9
1s 2s 2p 3s 3p 4s 3d

Bromine
1s22s22p63s23p64s23d104p5
10
Excited State Electrons


You can also draw and recognize elements with electrons
in the excited state from an electron configuration.
For example: What element is shown?
1s22s22p63s13p1
11
What did you answer?



This is NOT Aluminum (Al), this is Magnesium (Mg) in the
excited state!!
Why?
Look at the 3s sublevel…
1s22s22p63s13p1
12
Configurations for Ions


Add or remove the correct number of electrons and
write the new configuration.
Cu+2 ion
2
2
6
2
6
2
7
1s 2s 2p 3s 3p 4s 3d

13
Not 9, because the ion lost 2 electrons (it’s
configuration now looks like Cobalt’s.)