1. Subatomic Heavyweights

2. Opening Questions What is different about the two atoms above?
neutron
What is different about the two atoms above?
What is the atomic number of each atom above?
What is the mass number of each atom?
Do you think they are both lithium atoms? Why?

3. What up with that????
neutron
Both atoms are Lithium—same number of protons as the atomic number of Lithium
These atoms are ISOTOPES of one another.

4. What’s an isotope?
Atoms of the same element that have different numbers of neutrons.
Because of the different numbers of neutrons, the atoms have different masses.
neutron
Lithium-6
Lithium-7

5. Purpose of activity
How do isotopes of an atom account for the atomic weight of an element?

6. Post-Activity Questions
How are all the atoms of a single element the same? What does not change?
Explain why the atomic weight of an element is an average.
What do the numbers mean below?

7. Wrap-Up
How do potassium-39, potassium-40, and potassium-41 differ from each other?
How many electrons, protons, and neutrons are contained in each of the following atoms?
Fluorine-23
Molybdenum-96
What is the atomic weight of phosphorus? What is its atomic number? Predict which isotope you would find in greatest abundance for phosphorus.