1. Average Atomic Mass – GT

2. Drill
Complete Drill on back of what you should know page that you picked up! 

3. Agenda Drill Review of PhET Simulation Average Atomic Mass Notes
Practice
HW – Quiz next class

4. Average Atomic Mass
The weighted average mass of all the isotopes found in nature for that element

5. Units
Average Atomic Mass is measured in atomic mass units (amu)

6. Mass Spectrometer
Instrument that determines the percentages and individual masses of each isotope

7. A mass spectrometer produces charged particles (ions) from a chemical substance that are to be analyzed. The mass spectrometer then uses electric and magnetic fields to measure the mass of the charged particles.

8. Calculations
The average atomic mass is calculated by the percent of each isotope’s mass:
[(mass of isotope) (%abundance)] +
[(mass of isotope) (%abundance)] …

9. Practice Problem 1
Boron has two isotopes: Boron-10 and Boron-11. In nature 19% of Boron is Boron-10 and 81% is Boron- 11.

10. Practice Problem 2
A new element, Tyserium (Ty) has recently been discovered on Mars and consists of two isotopes. One isotope has a mass of 331 amu and is 35.0% abundant. The other isotope is 339 amu and is 65.0% abundant. What is the mass of Ty as it appears on the periodic table?

11. Logic Problem #1
Copper has an average atomic mass of amu and only exists as Copper-63 and Copper-65. What is the isotopic mass of the most common isotope of Copper?

12. Logic Problem #2
The relative atomic mass of chlorine is 35.5 amu. What does this tell you about the relative abundance of the two naturally occurring isotopes of chlorine, Chlorine-35 and Chlorine-37.

13. Check Yourself!
Make sure your calculated average mass is within the range of the given mass numbers
Rationalize your results
Check your answers on the periodic table

14. Quiz Layout of the Periodic Table History of the Atom Isotopes
**You can use your own Periodic Tables!! 