1. OA
How many protons, neutrons, and electrons are in an atom of chromium (Cr)?

2. How to Draw
Bohr Diagrams
and
Electron Dot Diagrams

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

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

5. C Bohr Diagrams Draw a nucleus with the element symbol inside.
Carbon is in the 2nd period, so it has two energy levels, or energy levels.
Draw the energy levels around the nucleus. C

6. C Bohr Diagrams Add the electrons. Carbon has 6 electrons.
The first energy level can only hold 2 electrons. C

7. Bohr Diagrams
Since you have 2 electrons already drawn, you need to add 4 more.
These go in the 2nd energy level.
Add one at a time -starting on the right side and going counter clock-wise. C

8. C Bohr Diagrams Check your work.
You should have 6 total electrons for Carbon.
Only two electrons can fit in the 1st energy level.
The 2nd energy level can hold up to 8 electrons.
The 3rd energy level can hold up to 18 electrons. C

9. Bohr Diagrams
Try the following elements on your own: H He O Al Ne K C

10. H Bohr Diagrams Try the following elements on your own: H – 1 electronAl Ne K H

11. Bohr Diagrams He Try the following elements on your own: H
He - 2 electrons O Al Ne K He

12. Bohr Diagrams O Try the following elements on your own: H He
O - 8 electrons Al Ne K O

13. Bohr Diagrams Al Try the following elements on your own: H He O
Al - 13 electrons Ne K Al

14. Bohr Diagrams Ne Try the following elements on your own: H He O Al
Ne - 10 electrons K Ne

15. Bohr Diagrams K Try the following elements on your own: H He O Al Ne
K - 19 electrons K

16. Electron Dot Diagrams
Electron dot diagrams are a way of representing an atom’s valence electrons. Remember! The valence electrons are those electrons that are in the highest energy level and held most loosely.

17. What is an electron dot diagram?
An electron dot diagram represents the valence electrons of an atom. It includes the symbol for the element surrounded by dots. Each dot stands for one valence electron.
An electron dot diagram is also sometimes called a Lewis structure.

18. Electron Dot Diagrams Find your element on the periodic table.
Determine the number of valence electrons.
This is how many electrons you will draw.

19. Periodic Table Review Group 18 = 8 valence electrons
Except for He which has 2 electrons
Group 2 = 2 valence electrons
Each column is called a “group” or “family”
3, 4, 5, 6, 7
Elements in a group have the same number of valence electrons.
This is why the elements in a group have similar properties.

20. Electron Dot Diagrams
Find out which group (family) your element is in.
This will tell you the number of valence electrons your element has.
You will only draw the valence electrons.

21. C Electron Dot Diagrams Write the element symbol.
Carbon is in the 4th group, so it has 4 valence electrons.
Starting at the right, draw 4 electrons, or dots, counter-clockwise around the element symbol. C

22. C Electron Dot Diagrams Check your work.
Using your periodic table, check that Carbon is in the 4th group.
You should have 4 total electrons, or dots, drawn in for Carbon. C

23. C Electron Dot Diagrams
On your worksheet, try these elements on your own: H P Ca Ar Cl Al C

24. H Electron Dot Diagrams
On your worksheet, try these elements on your own: H P Ca Ar Cl Al H

25. P Electron Dot Diagrams
On your worksheet, try these elements on your own: H P Ca Ar Cl Al P

26. Ca Electron Dot Diagrams
On your worksheet, try these elements on your own: H P Ca Ar Cl Al Ca

27. Ar Electron Dot Diagrams
On your worksheet, try these elements on your own: H P Ca Ar Cl Al Ar

28. Cl Electron Dot Diagrams
On your worksheet, try these elements on your own: H P Ca Ar Cl Al Cl

29. Al Electron Dot Diagrams
On your worksheet, try these elements on your own: H P Ca Ar Cl Al Al

30. Complete the Electron Dot (Lewis Structure) Worksheet You should know how to draw Lewis Structures for the first 20 elements.