1. Bohr Models are NOT Boring!
How to Draw Bohr Diagrams

2. Bohr Diagrams Find the element on the periodic table.
Determine the number of electrons--it is the same as the atomic number.
This is how many electrons you will draw.

3. Bohr Diagrams Find out which period (row) your element is in.1 2 3 4 5 6 7
Elements in the 1st period have one energy level.
Elements in the 2nd period have two energy levels, and so on.

4. Bohr Diagrams C Draw a nucleus with the element symbol inside.
Write the number of Protons and Neutrons the element has inside the nucleus. Put a + by the P and a little 0 by the N. C
P+ = 6
N0 = 6
Note: Round mass to nearest 1 when figuring neutrons.

5. The electron shells surrounding the nucleus each hold a particular number of electrons.
Shells are named with letters:
1 = K shell = 2 electrons
2 = L shell = 8 electrons
3 = M shell = 8 electrons
4 = N shell = 18 electrons
5-7 = O, P, Q = up to 32 electrons
Remember: The outer shell of an atom (no matter what letter) can only hold 8 electrons!

6. Bohr Diagrams
Carbon is in the 2nd period, so it has two energy levels, or shells.
Draw the shells around the nucleus. C
P+ = 6
N0 = 6

7. Bohr Diagrams C Add the electrons. Carbon has 6 electrons.
The first shell can only hold 2 electrons.
Write the number of electrons that shell holds and e- for electrons an their charge.
How many electrons are in the outer shell? C
P+ = 6
N0 = 6
2 e-

8. Bohr Diagrams
Since you have 2 electrons in the first shell, you need to add 4 more. C
P+ = 6
N0 = 6
These go in the 2nd shell.
Again, write e- and the number of electrons.
2e-
4e-

9. Bohr Diagrams C Check your work.
You should have 6 total electrons for Carbon.
Only two electrons can fit in the 1st shell.
The 2nd shell can hold up to 8 electrons.
The 3rd shell can hold 18, but the elements in the first few periods only use 8 electrons. We’ll talk about how they fill tomorrow. C
P+ = 6
N0 = 6
2e-
4e-

10. Bohr Diagrams
Try Hydrogen: Atomic Mass: Atomic Number: Protons: Electrons: Neutrons: Shells: Valence electrons: H
P+ =
N0 =

11. Bohr Diagrams
Check Yourself. H
P+= 1
N0= 0
1e-

12. Bohr Diagrams
Try Helium: Atomic Mass: Atomic Number: Protons: Electrons: Neutrons: Shells: Valence electrons:
Try Helium He
P+=
N0=

13. Bohr Diagrams He
P+= 2
N0= 2
Check Yourself!
2e-

14. Bohr Diagrams
Try Oxygen: Atomic Mass: Atomic Number: Protons: Electrons: Neutrons: Shells: Valence electrons: O
P+=
N0=

15. Bohr Diagrams
Check Yourslef! O
P+= 8
N0= 8
2e-
6e-

16. Bohr Diagrams
Try Aluminum: Atomic Mass: Atomic Number: Protons: Electrons: Neutrons: Shells: Valence electrons: Al
P+=
N0=

17. Bohr Diagrams
Check Yourself! Al
P+= 13
N0= 14
2e-
8e-
3e-

18. Bohr Diagrams
Try Potassium: Atomic Mass: Atomic Number: Protons: Electrons: Neutrons: Shells: Valence electrons: K
P+=
N0=

19. Bohr Diagrams
Check yourself! K
P+= 19
N0= 20
2e-
8e-
8e-
1e-

20. You should know how to draw a Bohr Diagram for the first 20 elements.
Bohr Diagrams
You should know how to draw a Bohr Diagram for the first 20 elements.