Bohr Models are NOT Boring! How to Draw Bohr Diagrams

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.

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.

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.

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!

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

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-

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-

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-

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

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

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

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

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

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

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

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

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

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

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.