Transcript How to Draw Bohr Diagrams

Bohr Models are NOT Boring!
How to Draw Bohr Diagrams
Prepared by Mrs. Hunt with help from
Mrs. LaRosa
Bohr Diagrams
1) Find the element on the periodic table.
2)Determine the number of electrons--it is the
same as the atomic number.
3)This is how many electrons you will draw.
Bohr Diagrams
1
• Find out which period
(row) your element is in.
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.
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Bohr Diagrams
1) Draw a nucleus with
the element symbol
inside.
C
P+ = 6
N0 = 6
2)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.
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 = L shell
3 = M shell
4 = N shell
5-7 = O, P, Q
= 2 electrons
= 8 electrons
= 8 electrons
= 18 electrons
= up to 32 electrons
Remember: The outer shell of an atom (no
matter what letter) can only hold 8 electrons!
Bohr Diagrams
C
P+ = 6
N0 = 6
1) Carbon is in the 2nd period,
so it has two energy levels,
or shells.
2) Draw the shells around the
nucleus.
Bohr Diagrams
1) Add the electrons.
C
P+ = 6
N0 = 6
2 e-
2) Carbon has 6 electrons.
3) The first shell can only
hold 2 electrons.
4) Write the number of
electrons that shell holds
and e- for electrons an
their charge.
5) How many electrons are
in the outer shell?
Bohr Diagrams
C
P+ = 6
N0 = 6
2e4e-
1) Since you have 2
electrons in the first
shell, you need to add
4 more.
2) These go in the 2nd
shell.
3) Again, write e- and the
number of electrons.
Bohr Diagrams
1) Check your work.
C
P+ = 6
N0 = 6
2e4e-
2) You should have 6 total
electrons for Carbon.
3) Only two electrons can fit in
the 1st shell.
4) The 2nd shell can hold up to 8
electrons.
5) 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.
Bohr Diagrams
H
P+ =
N0 =
Try Hydrogen:
Atomic Mass:
Atomic Number:
Protons:
Electrons:
Neutrons:
Shells:
Valence electrons:
Bohr Diagrams
Check Yourself.
H
P+= 1
N0= 0
1e-
Bohr Diagrams
He
P+=
N0=
Try Helium:
Helium
Atomic Mass:
Atomic Number:
Protons:
Electrons:
Neutrons:
Shells:
Valence electrons:
Bohr Diagrams
He
P+= 2
N0= 2
2e-
Check Yourself!
Bohr Diagrams
O
P+=
N0=
Try Oxygen:
Atomic Mass:
Atomic Number:
Protons:
Electrons:
Neutrons:
Shells:
Valence electrons:
Bohr Diagrams
Check Yourslef!
O
P+= 8
N0= 8
2e6e-
Bohr Diagrams
Al
P+=
N 0=
Try Aluminum:
Atomic Mass:
Atomic Number:
Protons:
Electrons:
Neutrons:
Shells:
Valence electrons:
Bohr Diagrams
Check Yourself!
Al
P+= 13
N0= 14
2e8e3e-
Bohr Diagrams
K
P+=
N 0=
Try Potassium:
Atomic Mass:
Atomic Number:
Protons:
Electrons:
Neutrons:
Shells:
Valence electrons:
Bohr Diagrams
Check yourself!
K
P+= 19
N0= 20
2e8e8e1e-
Bohr Diagrams
You should know how to
draw a Bohr Diagram for
the first 20 elements.
Periodic Table Study Guide
How to Draw Lewis
Structures
By Mrs. Hunt and Mrs. LaRosa
www.middleschoolscience.com 2008
Lewis Structures
1) Find the element on the periodic table.
2) Determine the number of valence electrons.
3) This is how many electrons you will draw.
Lewis Structures
• Find out which group
(column) your element is
in.
• This will tell you the
number of valence
electrons your element
has.
• You will only draw the
valence electrons.
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Groups - Review
Group 1 = 1 electron
Group 2 = 2 electrons
Group 8 = 8 electrons
Except for He, it has 2
electrons
•Each column is
called a “group”
•Each element in a
group has the same
number of electrons
in their outer orbital,
also known as
“shells”.
•The electrons in the
outer shell are called
“valence electrons.”
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Lewis Structures
1) Write the element
symbol.
2) Carbon is in the 4th
group, so it has 4
valence electrons.
3) Starting at the right,
draw 4 electrons, or
dots, counterclockwise around the
element symbol.
Lewis Structures
1) Check your work.
2) Using your periodic
table, check that
Carbon is in the 4th
group.
3) You should have 4
total electrons, or
dots, drawn in for
Carbon.
Lewis Structures
On your worksheet, try
these elements on your own:
a)
b)
c)
d)
e)
f)
H
P
Ca
Ar
Cl
Al
Lewis Structures
On your worksheet, try
these elements on your own:
a)
b)
c)
d)
e)
f)
H
P
Ca
Ar
Cl
Al
Lewis Structures
On your worksheet, try
these elements on your own:
a)
b)
c)
d)
e)
f)
H
P
Ca
Ar
Cl
Al
Lewis Structures
On your worksheet, try
these elements on your own:
a)
b)
c)
d)
e)
f)
H
P
Ca
Ar
Cl
Al
Lewis Structures
On your worksheet, try
these elements on your own:
a)
b)
c)
d)
e)
f)
H
P
Ca
Ar
Cl
Al
Lewis Structures
On your worksheet, try
these elements on your own:
a)
b)
c)
d)
e)
f)
H
P
Ca
Ar
Cl
Al
Lewis Structures
On your worksheet, try
these elements on your own:
a)
b)
c)
d)
e)
f)
H
P
Ca
Ar
Cl
Al
End of Study Guide.
Complete the Lewis Structure
Worksheet
You should know how to draw
Lewis Structures for the first
20 elements.