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Unknown #1
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Color Burned
How to draw Bohr Diagrams and Electron Dot
Diagrams (sometimes called Lewis Structures)

Pictographic representation of an Atom
Shows information about the nucleus
Electron energy levels
Good for index cards and flash cards
Start with a rectangle about 2” x 4”
At the top write the name, Atomic number,
Mass number of the element and the atomic
mass
Carbon
Atomic # = 6
Mass # = 12
Atomic mass = 12.011 amu
Draw a small circle below the text that
will represent the nucleus of the atom
Carbon
Atomic # = 6
Mass # = 12
Atomic mass = 12.011 amu
C 6p+
6n0
In the circle write:
the elemental
symbol
the number of
Protons
the number of
Neutrons
Draw a larger circle around the nucleus circle to
represent the first energy level for electrons
Carbon
Atomic # = 6
Mass # = 12
Atomic mass = 12.011 amu
Carbon is in
Period two and
therefore needs
two energy levels
C 6p+
6n0
Add more
circles outside
to include all
of the energy
levels you
need for the
atom.
(Hint: In what
period is the
element?)



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.
Now add electrons, as small dots, to each
energy level as allowed until you have the proper
number of electrons for a neutral element.
The number
of electrons
should be
equal to the
number of
protons.
Carbon
Atomic # = 6
Mass # = 12
Atomic mass = 12.011 amu
C 6p+
6n0
Remember:
Energy
Level
# of e-
1
2
2
8
3
8
If you need a third
level make your
circles a little
smaller.
You now have a complete Bohr Diagram
Carbon
Atomic # = 6
Mass # = 12
Atomic mass = 12.011 amu
C 6p+
6n0
1)
C
2)
3)
Draw a nucleus
with the element
symbol inside.
Carbon is in the
2nd period, so it
has two energy
levels, or shells.
Draw the shells
around the
nucleus.
1)
C
2)
3)
Add the electrons.
Carbon has 6
electrons.
The first shell can
only hold 2
electrons.
1)
C
2)
3)
Since you have 2
electrons already
drawn, you need to
add 4 more.
These go in the 2nd
shell.
Add one at a time
-starting on the
right side and
going counter
clock-wise.
1)
2)
C
3)
4)
5)
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.
Try the following
elements on your
own:
C
a)
b)
c)
d)
e)
f)
H
He
O
Al
Ne
K
Try the following
elements on your
own:
H
a)
b)
c)
d)
e)
f)
H – 1 electron
He
O
Al
Ne
K
Try the following
elements on your
own:
H
e
a)
b)
c)
d)
e)
f)
H
He - 2 electrons
O
Al
Ne
K
Try the following
elements on your
own:
O
a)
b)
c)
d)
e)
f)
H
He
O - 8 electrons
Al
Ne
K
Try the following
elements on your
own:
Al
a)
b)
c)
d)
e)
f)
H
He
O
Al - 13 electrons
Ne
K
Try the following
elements on your
own:
N
e
a)
b)
c)
d)
e)
f)
H
He
O
Al
Ne - 10 electrons
K
Try the following
elements on your
own:
K
a)
b)
c)
d)
e)
f)
H
He
O
Al
Ne
K - 19 electrons
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
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Also called Lewis Structures
Representation of valence electrons only
Useful only for “Representative elements”
Gives some indication of the geometry
(shape) of compounds when used for bonding
diagrams
Easy to draw
To find the # of valence electrons look at the
group
 Group 1
 Group 2
 Group # =
# of valence
electrons


The Elemental Symbol serves as the
representation of the nucleus

Dots are added around the nucleus to show
electrons only in the outer energy level
Like the Hund rule
add 1 electron per
side, then add more
as needed.
Carbon has only 4 electrons in the 2nd energy level so
we need only represent those 4

Lewis structures only apply to
“Representative elements” (Group A
elements)
The maximum
number of electrons
that can be shown
are 8
Only s and p sublevel electrons in the outer or highest
energy level are shown. These are called valence
electrons.

Lewis structures only apply to
“Representative elements” (Group A
elements)
The maximum
number of electrons
that can be shown
are 8
Only s and p sublevel electrons in the outer or highest
energy level are shown. These are called valence
electrons.

Lewis structures only apply to
“Representative elements” (Group A
elements)
The maximum
number of electrons
that can be shown
are 8
Only s and p sublevel electrons in the outer or highest
energy level are shown. These are called valence
electrons.

Lewis structures only apply to
“Representative elements” (Group A
elements)
The maximum
number of electrons
that can be shown
are 8
Only s and p sublevel electrons in the outer or highest
energy level are shown. These are called valence
electrons.

Transition metals don’t have valence
electrons. They have Oxidation Numbers
+2
+2
We’ll Talk about Oxidation Numbers Next Week!
+2
+4