1. (Bohr & Electron Configuration Orbital Diagrams )
Electron Orbitals
And Drawing
Atomic Diagrams
(Bohr & Electron Configuration Orbital Diagrams )

2. What does an Atom look like?
The Niels Bohr’s Model

3. Bohr’s Planetary Model
Bohr proposed that electrons are RESTRICTED to certain FIXED orbits around the nucleus.
It’s called the Planetary Model because it mimics our solar system.

4. Energy in each level
Energy Level closest to nucleus have - Low Energy Electrons
Energy Level farthest from the nucleus have - High Energy Electrons
It’s very much like the
Hammer Throw event.

5. Energy in each level
Energy Level closest to nucleus have - Low Energy Electrons
Energy Level farthest from the nucleus have - High Energy Electrons
It’s very much like the
Hammer Throw event.
When the throw begins, the Hammer is being spun slowly.
Notice how close it is to the body.
As the spin increases.
Notice how far away it is to the body.

6. Bohr’s Planetary Model
Bohr also proposed that electrons can “Jump” suddenly between those orbits by gaining or losing energy.
Loses Energy = “Jumps” DOWN
Gains Energy = “Jumps” UP

7. Bohr’s Planetary Model
Each of these orbits (or Shells) could only hold a set number of electrons at any one given point in time. n7 n6 n5
n1= maximum of 2 electrons n4
n2= maximum of 8 electrons n3 n2
n3= maximum of 18 electrons n1
n4= maximum of 32 electrons
n5= maximum of 50 electrons
n6= maximum of 72 electrons
Maximum electrons = 2(n2)
n7= maximum of 98 electrons

8. How to draw Bohr diagrams:
Step 1: Determine how many Protons, Neutrons, and Electrons are in the atom.
Step 2: Write the number of Protons and Neutrons in a circle to represent the Nucleus.
Step 3: Fill in the energy shells with ALL of the electrons from inner to outer.
(Once a Shell is completely filled, then move to the next.)
Oxygen
# of p = _____
# of e = _____
# of n = _____ 8 8p 8n 8 8 2 6

9. How to draw Bohr diagrams:
Let’s try another:
53p
74n 2 8
Iodine
# of p = _____
# of e = _____
# of n = _____ 18 53 25 53 74

10. Let’s check the valance charges?
Oxygen
Valence (-2)
Outer level has 6 of 8
Iodine
Valence (-1)
Outer level has 25 of 32

11. Bohr’s Planetary Model
But wait, Something doesn’t make sense?
We said that once ALL atoms get 8 electrons in their outmost layer, they are Stable.
And once they are stable they no longer need any more electrons.
Reply hazy, try again
So why are there MORE than 8 in levels n3 – n7?
A NEW model was needed!

12. So along comes Quantum Mechanics and
Erwin Schrodinger
Electrons are NOT particles, They are WAVES.

13. Schrodinger Model
Electrons DO NOT travel as particles in FIXED orbits.
They are free to move around the nucleus
but they do tend to occur more frequently in certain areas of the electron cloud at any given time.
These areas of probability were mathematically found and are known as Orbitals
Click here
Electron Cloud is like a Fenced in Back Yard. A dog is allowed to run anywhere in there, BUT there is a higher probability that you will find the dog at certain locations (Near the Door, by a tree to pee, etc.)

14. Orbital Shapes – s Orbitals
s Orbitals are Spherical
ONLY ONE s Orbital for every Energy level (n)
Remember:
Each Orbital can only Hold 2 electrons no matter what shape it has.
EVERY s Level (n)
Total of 2 electrons

15. Orbital Shapes – p Orbitals
p Orbitals are Dumbbell shaped
THREE p Orbitals for every Energy level (n)
Remember:
Each Orbital can only Hold 2 electrons no matter what shape it has.
EVERY p Level (n)
Total of 6 electrons

16. Orbital Shapes – d Orbitals
d Orbitals are odd shaped
FIVE d Orbitals for every Energy level (n)
EVERY d Level (n)
Total of 10 electrons
Remember:
Each Orbital can only Hold 2 electrons no matter what shape it has.

17. Orbital Shapes – f Orbitals
f Orbitals are VERY odd shaped
SEVEN f Orbitals for every Energy level (n)
EVERY f Level (n)
Total of 14 electrons
Remember:
Each Orbital can only Hold 2 electrons no matter what shape it has.

18. Still confused? Try watching this.
(This video can also be found on Mr. Racchini’s website)

19. Filling the ENERGY LEVELS
Electron Orbital Diagrams
Rule 1 - Aufbau Principle
Lowest energy orbitals fill first. Thus, the filling pattern is 
1s, 2s, 2p, 3s, 3p, 4s, 3d, etc.
n=1 1s
n=2 2s 2p
n=3 3s 3p 3d
n=4 4s 4p 4d 4f
n=5 5s 5p 5d 5f
n=6 6s 6p 6d
n=7 7s 7p
n=8 8s

20. Filling the ENERGY LEVELS
Electron Orbital Diagrams
Rule 2 - Pauli Exclusion Principle
Only two electrons are permitted per orbital and they must have an opposite spin.  Up
Spin
Down
Spin
n=1 1s
Stable Orbitals
When electrons are found this way, in the same orbital, they are referred to as being paired and no longer need to find another electron.

21. Filling the ENERGY LEVELS
Rule 3 - Hund's Rule
When assigning electrons in energy levels, each electron will first fill all the orbitals with similar energy before pairing with another electron in a half-filled orbital. 
The Bus Seat Rule 

22. Filling the ENERGY LEVELS
Rule 3 - Hund's Rule
The Bus Seat Rule 
2) You search for a seat 
1) You get on the Bus 
3) You find an empty row 

23. Filling the ENERGY LEVELS
Valence Charge
Rule 3 - Hund's Rule
Filling the orbitals is just like getting on a bus. 
Oxygen
(8 electrons) -2
2p = ___ ___ ___
Think of each energy level like the bus.
2s = ___
And think of each Orbital as a row on that bus.
1s = ___

24. So what order do the orbitals fill?
Remember the Aufbau Principle
Or…

25. Just know the areas of the Periodic Table of Elements:
s Orbitals
Just know the areas of the Periodic Table of Elements:
p Orbitals
d Orbitals n=
f Orbitals 1 1s 2 2s 2p 3 3s 3p 4 4s 3d 4p 5 5s 4d 5p 6 6s 5d 6p 7 7s 6d 7p 4f 5f

26. How do you write an Atom’s…
Electron configuration / Orbital Diagram
Step 1: Find the atom on the Periodic Table of Elements
Example: ________________
Sodium
Step 2: STARTING with Hydrogen, move left to right and top to bottom across the table so you can write down all of the orbitals up to your atom.

27. s Orbitals p Orbitals d Orbitals f Orbitals n= 1 2 3 4 5 6 7 1s 1s 2s

28. How do you write an Atom’s…
Electron configuration / Orbital Diagram
Step 3: Make a chart of all of the orbitals up to your atom.
Sodium
(11 TOTAL electrons)
Remember: All…
“s” have 1 orbital
“p” have 3 orbitals
“d” have 5 orbitals
“f” have 7 orbitals
3s =
2p =
Step 4: Following Hund’s Rule, and The Aufbau and Pauli Exclusion principles, place all of the electrons into your chart.
2s =
1s =

29. How do you write an Atom’s…
Electron configuration / Orbital Diagram
Step 5: Now write the Electron configuration.
1s2
2s2
2p6
3s1

30. How do you write an Atom’s…
Electron configuration / Orbital Diagram
Step 6: Sometimes these can be very long, so to save time and paper space you may replace the beginning of it with [ ] and the last Nobel Gas
1s22s22p63s1
[Ne]3s1

31. Selenium 4p = 3d = 4s = 3p = 3s = 2p = 2s = 1s = Selenium
Let’s try another example:
Selenium
(34 TOTAL electrons)
4p =
Selenium
3d =
4s =
3p =
3s =
2p =
2s =
1s =

32. How do you write an Atom’s…
Electron configuration / Orbital Diagram
Try another example on your own:
Selenium
1s22s22p63s23p64s23d104p4
[Ar]
4s23d104p4