1. Using the Bohr Model to Build an Atom

2. Remember what the periodic table gives you…
# of p+ Or
# of e-
Atomic Number 7 = N
Chemical Symbol
14.007
Atomic Mass =
(# of n0) + (# of p+)

3. Number of Neutrons? You’ll need to do a little calculation…
Remember that:
Atomic number = p+
Atomic mass = (p+) + (n0)
So to calculate # of n0…
[(p+) + (n0)] – (p+) =
Atomic mass – Atomic Number = # of neutrons n0

4. Let’s Build an Atom… He = p+ = n0 = e- 2 4.0026
Step 1: Build the Nucleus – insert protons.
Step 2: Build the Nucleus – insert neutrons.
Step 3: Construct the first orbital and fill it with up to 2 electrons.

5. Let’s Build a Bigger Atom…5
10.811
Step 1: Build the Nucleus – insert protons.
Step 2: Build the Nucleus – insert neutrons.
Step 3: Construct the first orbital and fill it with up to 2 electrons.
Step 4: Construct the second orbital and fill it with up to 8 electrons.

6. How Can We Do This On Paper?15
30.974
15p+
2e-
8e-
5e-
16n0
Step 1: Build the Nucleus – insert protons.
Step 2: Build the Nucleus – insert neutrons.
Step 3: Construct the first orbital and fill it with up to 2 electrons.
Step 4: Construct the second orbital and fill it with up to 8 electrons.
Step 5: Construct the third orbital and fill it with up to 8 electrons.

7. One More Time!! Mg 12 24.305 12p+ 2e- 8e- 2e- 12n0
Step 1: Build the Nucleus – insert protons.
Step 2: Build the Nucleus – insert neutrons.
Step 3: Construct the first orbital and fill it with up to 2 electrons.
Step 4: Construct the second orbital and fill it with up to 8 electrons.
Step 5: Construct the third orbital and fill it with up to 8 electrons.