1. Periodic Table www.middleschoolscience.comwww.middleschoolscience.com 2008 How to Draw Bohr Diagrams

2. Learning Scale 4 – Investigate and describe the compounds formed by bonding elements. 3 – Describe why certain elements bond with others. 2 – Use the periodic table to identify the number of protons, neutrons, or electrons in an element. 1 – Identify patterns on the periodic table.

3. Review – Timed Pair Share You have 30 seconds to share with your partner. 1.How can you determine the number of protons, electrons, and neutrons in an element?

4. Review – Timed Pair Share 1.Explain how the periodic table is organized and how it is useful to scientists.

5. Previewing Content Why is it important for elements to be able to join together to form compounds?

6. Energy Levels How many electrons can each level hold? 1 st level = 2 2 nd level = 8 3 rd level = 18 4 th level = 32

7. Valence Electrons Valence electrons are the electrons found in the outer energy level. We will only be using Groups 1-2 and Groups 13-18.

8. Valence Electrons The last number of the group number = the number of valence electrons. Examples Group 2 = 2 valence electrons Group 18 = 8 valence electrons

9. Bohr Diagrams 1)Find your element on the periodic table. 2)Determine the number of electrons – it is the same as the atomic number. 3)This is how many electrons you will draw.

10. Bohr Diagrams Find out which period (row) your element is in. Elements in the 1 st period have one energy level. Elements in the 2 nd period have two energy levels, and so on. www.chem4kids.com

11. Bohr Diagrams C C 1) Draw a nucleus with the element symbol inside. 2) Carbon is in the 2 nd period, so it has two energy levels, or shells. 3) Draw the shells around the nucleus.

12. Bohr Diagrams 1) Add the electrons. 2) Carbon has 6 electrons. 3) The first shell can only hold 2 electrons. C C

13. Bohr Diagrams 1) Since you have 2 electrons already drawn, you need to add 4 more. 2) These go in the 2 nd shell. 3) Add one at a time - starting on the right side and going counter clock-wise. C C

14. Bohr Diagrams 1) Check your work. 2) You should have 6 total electrons for Carbon. 3) Only two electrons can fit in the 1 st shell. 4) The 2 nd shell can hold up to 8 electrons. 5) The 3 rd shell can hold 18, but the elements in the first few periods only use 8 electrons. C C

15. Bohr Diagrams Try the following elements on your own: a)H b)He c)O d)Al e)Ne f)K C C

16. Bohr Diagrams Try the following elements on your own: a)H – 1 electron b)He c)O d)Al e)Ne f)K H H

17. Bohr Diagrams Try the following elements on your own: a)H b)He - 2 electrons c)O d)Al e)Ne f)K He

18. Bohr Diagrams Try the following elements on your own: a)H b)He c)O - 8 electrons d)Al e)Ne f)K O O

19. Bohr Diagrams Try the following elements on your own: a)H b)He c)O d)Al - 13 electrons e)Ne f)K Al

20. Bohr Diagrams Try the following elements on your own: a)H b)He c)O d)Al e)Ne - 10 electrons f)K Ne

21. Bohr Diagrams Try the following elements on your own: a)H b)He c)O d)Al e)Ne f)K - 19 electrons K K

22. Which elements want to bond? Octet Rule The magic number for all elements (except H and He) is 8. This means that they will gain or lose electrons in order to get 8 in their outer energy level.

23. Who gains? Who loses? More electrons = gain Less electrons = lose

24. Review Questions  Group 1 has __ valence electrons. It needs _.  Which group will it bond with? Why?  Will it lose or gain electrons?  Group 16 has __ valence electrons. It needs _.  Which group will it bond with? Why?  Will it lose or gain electrons?

25. Learning Scale 4 – Investigate and describe the compounds formed by bonding elements. 3 – Describe why certain elements bond with others. 2 – Use the periodic table to identify the number of protons, neutrons, or electrons in an element. 1 – Identify patterns on the periodic table.