Drawing Atoms

Thanks to Mrs. LaRosawww.middleschoolscience.com 2008

How to Draw Bohr Diagrams

Bohr Diagrams

1) Determine the number of protons: 2) # protons = atomic number3) This is how many protons will go in the

nucleus.

Bohr Diagrams1) Now figure out how many neutrons.2) Neutrons = Atomic Mass (round off)-# protons.3) This is how many neutrons will go in the

nucleus.

Bohr Diagrams

1) Determine the number of electrons 2) # electrons = # protons3) This is how many electrons you will draw in

the energy levels or energy clouds.

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.

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Where do the electrons go?

• Putting electrons into an atom is like filling seats at a concert:– First row fills up first, then second row, then third

row.• Each energy level has a limited number of

spots (like seats in a concert)– First energy level: 2 electrons– Second energy level: 8 electrons– Third energy level: 8 electrons

Bohr Diagrams

p+=6n=6p+=6n=6

1) Draw a nucleus with the correct number of protons and neutrons inside.

2) Carbon is in the 2nd period, so it has two energy levels or clouds.

3) Draw the energy levels around the nucleus.

Carbon

Bohr Diagrams

1) Add the electrons.

2) Carbon has 6 electrons.

3) The first level can only hold 2 electrons.

p+=6n=6p+=6n=6

Bohr Diagrams

1) Since you have 2 electrons already drawn, you need to add 4 more.

2) These go in the 2nd energy level.

3) Add one at a time -starting on the right side and going counter clock-wise.

p+=6n=6p+=6n=6

Bohr Diagrams

1) Check your work.

2) You should have 6 total electrons for Carbon.

3) Only two electrons can fit in the 1st level.

4) The 2nd level can hold up to 8 electrons.

5) The 3rd level can hold 8, but Carbon doesn’t use that level.

p+=6n=6p+=6n=6

Bohr Diagrams

Try the following elements on your own:

O8 protons8 neutrons2 energy levels8 electrons

p+=8n=8p+=8n=8

Bohr Diagrams

Try the following elements on your own:

Al13 protons14 neutrons3 energy level13 electron

p+=13

n=14

p+=13

n=14

Bohr Diagrams

Try the following elements on your own:

Ar18 protons22 neutrons3 energy levels18 electrons

p+=18

n=22

p+=18

n=22

Bohr DiagramsTry the following element on your own:

H1 proton0 neutrons1 energy level1 electron

p+=1n=0p+=1n=0

Bohr Diagrams

Try the following elements on your own:

a) Hb) He - 2 electronsc) Od) Ale) Nef) Ar

p+=2n=2p+=2n=2

Bohr Diagrams

Try the following elements on your own:

a) Hb) Hec) Od) Ale) Ne - 10 electronsf) Ar

p+=10

n=10

p+=10

n=10

Bohr Diagrams

End of Study Guide.

You should know how to draw a Bohr Diagram for

the first 18 elements.