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Bohr Model diagrams
are used to represent
the electron
structures of
elements
Protons and neutrons
are placed in the
middle to represent
the nucleus
Electrons are placed
in the electron shells
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Using the example Fluorine, we will work
through the steps in creating a Bohr model
Right now, look at your periodic table and
find the element Fluorine.
Draw in what Fluorine looks like on the
Periodic Table in the box on your sheet
1.
Determine the number of subatomic
particles found in the element
◦ Number of electrons is equal to the number of
protons in the neutral atom. This value is equal to
the atomic number
◦ Number of neutrons is calculated using the
equation Atomic Mass MINUS Atomic Number
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Fluorine Example
◦ Number of protons = 9
◦ Number of electrons = 9
◦ Number of neutrons = 19 – 9 = 10
2. Draw a circle for the nucleus with the correct
number of and symbol for both protons and
neutrons.
◦ Letter symbol for protons: p
◦ Letter symbol for neutrons: n
Fluorine example
p9
n10
3. Draw the correct number of electron shells
◦ First ring has a maximum of 2 electrons
◦ Second ring has a maximum of 8 electrons
◦ Third ring has a maximum of 8 electrons
*Electron shells must be filled to their maximum
before another ring is added
FLUORINE EXAMPLE
 Fluorine has 9 electrons
 The first electron shell has 2 electrons
 9 minus 2 = 7
 The second electron shell will have 7
electrons
** The electrons in the outer shell are referred
to as valence electrons.
4. Represent electrons as dots and position
electrons in shells.
 The electron shells are also referred to as
electron orbitals
 The electrons will fill the orbit of the lowest
energy level first (i.e. first electron shell
closest to the nucleus). The first shell can
hold a maximum of 2 electrons
An electron shell must be filled with its
maximum number of electrons before any
additional electron shells can be filled
 Electrons should be distributed evenly and
neatly throughout the shell
FLUORINE EXAMPLE
In the Fluorine atom, the first shell contains 2
electrons and the second contains 7
electrons.
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