Transcript Modeling and Representing Atoms on Paper

Modeling and Representing
Atoms on Paper
How to draw Bohr Diagrams and
Electron Dot Diagrams
(sometimes called Lewis
Structures)
Bohr Diagrams
Pictographic representation of an Atom
Shows information about the nucleus
Electron energy levels
Good for index cards and flash cards
Bohr Diagrams
Start with a rectangle about 2” x 4”
Bohr Diagrams
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
Bohr Diagrams
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
Bohr Diagrams
Draw a larger circle around the nucleus circle
to represent the first energy level for
electrons
Carbon
Add more circles
Atomic # = 6
outside to
Mass # = 12
Atomic mass = 12.011 amu
include all of
the energy
levels you need
Carbon is in
for the atom.
Period two and
therefore needs
(Hint: In what
two energy
period is the
levels
element?)
C 6p+
6n0
Bohr Diagrams
Now add electrons, as small dots, to each
energy level as allowed until you have the
proper number of electrons for a neutral
element.
Remember:
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
Energ
y
Level
# of e-
1
2
2
8
3
8
If you need a third level
make your circles a little
smaller.
Bohr Diagrams
You now have a complete Bohr Diagram
Carbon
Atomic # = 6
Mass # = 12
Atomic mass = 12.011 amu
C 6p+
6n0
Electron Dot Diagrams
• 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
Electron Dot Diagrams
• The Elemental Symbol serves as the
representation of the nucleus
Electron Dot Diagrams
• 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
Electron Dot Diagrams
• 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.
Electron Dot Diagrams
• 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.
Electron Dot Diagrams
• 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.
Electron Dot Diagrams
• 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.
Electron Dot Diagrams
• Transition metals don’t have valence
electrons. They have Oxidation Numbers
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We’ll Talk about Oxidation Numbers Next Week!
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