Transcript notes

Topic #8: Bohr Models and
Lewis dot Diagrams
EQ: How do Bohr models and
Lewis dot diagrams help us
illustrate an atom’s structure?
What do we know?
Atoms have 2 main parts
Electron cloud -- contains electrons
Nucleus – contains protons and neutrons
Electrons = eProtons = p+
Neutrons = n0
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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)

How many electrons per orbital?
Period 1 
orbital (ring) 1: 2 e-
Period 2 
orbital (ring) 1: 2 eorbital (ring) 2: 8 e-
Period 3 
orbital (ring) 1: 2 eorbital (ring) 2: 8 eorbital (ring) 3: 8 e-
Period 4 
orbital (ring) 1: 2 eorbital (ring) 2: 8 eorbital (ring) 3: 18 eorbital (ring) 4: 8 e-
Information to create a Bohr model
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Element name and symbol:
Magnesium (Mg)
Atomic number: 12
Mass number: 24
Protons: 12
Electrons: 12
Neutrons: (24 - 12) = 12
Bohr model for Mg
12p+
12n
Bohr model for Al
13p+
14n0
Valence Electrons
Valence electrons are electrons on the last
energy level.
 How many Valence electrons does
aluminum have?

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)
3 6

7
4
Al
X
85
2
1
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