1. Bohr Models

2. Making a Bohr Model
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

3. How to Construct Bohr Model Diagrams
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

4. Steps to Make a Bohr Model
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

5. Steps to Make a Bohr Model
Fluorine Example
Number of protons = 9
Number of electrons = 9
Number of neutrons = 19 – 9 = 10

6. Steps to Make a Bohr Model
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

7. Steps to Make a Bohr Model
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

8. Steps to Make a Bohr Model
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.

9. Steps to Make a Bohr Model
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

10. Steps to Make a Bohr Model
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.

11. Bohr Model Example