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

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.

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

Review – Timed Pair Share Why is it important for elements to be able to join together to form compounds?

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

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. www.chem4kids.com

Bohr Diagrams Find your 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.

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

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

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

C Bohr Diagrams 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. C

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

H Bohr Diagrams Try the following elements on your own: H – 1 electron Al Ne K H

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

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

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

Understanding Check How do you find the number of electrons? How many electrons can be in the 1st level? 2nd level?

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

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

The Next Step Why do some elements bond to form compounds?

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.

Valence Electrons Valence electrons are the electrons found in the outer energy level. Valence electrons determine who bonds with who.

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

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.

Atomic Dating Game Model What would the Bohr diagram for Beryllium look like?

What do I know about Beryllium? 4 total electrons 2 valence electrons What is the magical number of valence electrons? How many more does it need?

Who should Beryllium date (bond with)? Why?