1. Topic #8: Bohr Models and Lewis dot Diagrams
EQ: How do Bohr models and Lewis dot diagrams help us illustrate an atom’s structure?

2. What do we know? Atoms have 2 main parts
Electron cloud -- contains electrons
Nucleus – contains protons and neutrons
Electrons = e-
Protons = p+
Neutrons = n0

3. What do you need to know? There are 7 possible orbitals
You can determine how many orbitals your model has by looking at what period (row) the element is on
The orbitals hold a specific number of electrons (which is the same as the atomic number)

4. How many electrons per orbital?
Period 1  orbital (ring) 1: 2 e-
Period 2  orbital (ring) 1: 2 e-
orbital (ring) 2: 8 e-
Period 3  orbital (ring) 1: 2 e-
orbital (ring) 3: 8 e-
Period 4  orbital (ring) 1: 2 e-
orbital (ring) 3: 18 e-
orbital (ring) 4: 8 e-

5. Information to create a Bohr model
Element name and symbol: Magnesium (Mg)
Atomic number: 12
Mass number: 24
Protons: 12
Electrons: 12
Neutrons: ( ) = 12

6. Bohr model for Mg
12p+
12n

7. Bohr model for Al
13p+
14n0
Ask “How many orbitals should Al have?”; “How many protons?”; “How many neutrons?”; “How many electrons in the first orbital?”; “How many electrons in the second orbital?”; “How many electrons in the third orbital?”; “What is so special about these 3 electrons?”

8. Valence Electrons
Valence electrons are electrons on the last energy level.
How many Valence electrons does aluminum have?

9. X Lewis Dot Diagrams Lewis dot diagrams are simple to draw:
Step one: Write symbol from the periodic table.
Step Two: Add the correct number of valence electrons around the symbol.
(preferred fill pattern) Al 3 6 X 7 2 4 1 8 5

10. Aluminum Silicon Phosphorus Sulfur Chlorine
Draw the following Bohr models and Lewis dot diagrams on your blank sheet of paper at the beginning of the topic.
Boron Carbon Nitrogen Oxygen Fluorine
Aluminum Silicon Phosphorus Sulfur Chlorine