# Average Atomic Mass - GT Average Atomic Mass GT Drill Complete the half sheet you grabbed on your way in!

Now Take out your Periodic Table/Periodic Table Notes, History of the Atom, and Build an Atom Notes Agenda

Drill Average Atomic Mass Notes Practice HW Quiz next class Average Atomic Mass

The weighted average mass of all the isotopes found in nature for that element Units

Average Atomic Mass is measured in atomic mass units (amu) Mass Spectrometer

Instrument that determines the percentages and individual masses of each isotope

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

+ [(mass of isotope) (%abundance)] 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. 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? Logic Problem #1

Copper has an average atomic mass of 63.546 amu and only exists as Copper-63 and Copper65. What is the isotopic mass of the most common isotope of Copper? 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. 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 Quiz Layout of the Periodic Table History of the Atom

Isotopes Average Atomic Mass You will be able to use a Periodic Table!!!