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Student Learning Map
• Left Side:
• LEQ2: How are atoms represented
via Bohr Models?
Energy Levels and
Bohr Diagrams
Energy Levels
• Energy levels are the possible
energies and locations an electron
in an atom can have.
• This is like the possible floors to
rent a room in a hotel.
• Each level is a certain distance from
the nucleus—the further you get
from the nucleus (or ground floor),
the greater the energy required and
the greater the energy level.
• Each energy level is symbolized by
“n” and a number.
Energy Level Diagrams
The diagram below shows you all
the possible energy levels and
how they are labeled:
Nucleus
n=1
n=2
n=3
n=4
n=5
n=6
n=7
Electrons and Energy Levels
• An electron’s energy level (and
location) depends on how much
energy the electron has.
• All electrons fill the lowest energy
level first and will only fill a higher
energy level if there is no more
room in the one below it.
Maxing Out Energy Levels
To know if an energy level is full,
you must check the maximum
number of electrons for each
energy level.
Energy Level
1
2
3
4
5
6
7
Maximum Number of Electrons
2
8
18
32
32
18
8
Drawing an Energy Level
Diagram
1. Calculate how many protons (atomic
number), how many electrons (protons –
charge) and how many neutrons there
are (mass # – atomic #).
Example: Arsenic-75
• Protons: 33
• Electrons: 33 – 0 = 33
• Neutrons: 75 – 33 = 42
Drawing an Energy Level
Diagram
2. Draw the nucleus and write how
many protons and how many
neutrons are in the atom.
Example: Arsenic
• p+ means protons
• n means neutrons
p+ = 33
n = 42
Drawing an Energy Level
Diagram
3. Add electrons to energy level n = 1.
Stop when you run out of electrons
OR when you fill the energy level,
whichever happens first.
Example: Arsenic
• Only 2 electrons of
arsenic’s 33 total
electrons can fit in
energy level n = 1.
p+ = 33
n = 42
Drawing an Energy Level
Diagram
4. If you still have more electrons in the
atom, go to energy level n = 2. Continue
to fill in your electrons until you run out
of electrons OR when you fill the energy
level, whichever happens first.
Example: Arsenic
• Since only 2
electrons fit in n = 1,
we must move to
n = 2. Eight more fit
here for a total of 10.
p+ = 33
n = 42
Drawing an Energy Level
Diagram
5. If you still have more electrons,
repeat step 4 for each energy level
until you run out of electrons. Only
draw the energy levels that have
electrons in them.
n = 1  2 e-
Example:
Arsenic
n = 2  8 en = 3  18 e= 33
n = 4  5 e-
n = 42
n = 5  0 e-
p+
n = 6  0 en = 7  0 e-
Total = 33 e-
Calcium-42
Calcium-44
• Isotopes are two atoms of the
same element (aka same number
of protons) that have a different
number of neutrons (aka mass
number).
• Draw the Bohr Energy Level
Diagram for Calcium-44.
28 +3
Al
13
Ba
+2
Chlorine-40
Think about it . . .
• Why must the electrons be spaced
as far apart as possible within
each energy level?
• Which electron, one in n=3 or one
in n=5 has more energy? Why is
this true?
Find your Isotope Partner
• Each of you will make a poster on
your specific isotope
• It must include the name of the
isotope and a Bohr Model of the
isotope including n levels
• Also must include the following
table for your isotope
Isotope
Name
Nuclear
Symbol
Atomic #
Mass #
Protons
Neutrons Electrons