Student Exploration: Average Atomic Mass75 pts (Class Code T94GGP)Vocabulary: average atomic mass, isotope, mass defect, mass number, mass spectrometer,nuclear binding energy, unified atomic mass unit, weighted averagePrior Knowledge Questions (Do these BEFORE using the Gizmo.)1. In the image to the right, the cans of soup havedifferent masses. Without doing the math,estimate the average mas
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Student Exploration: Average Atomic Mass
75 pts (Class Code T94GGP)
Vocabulary: average atomic mass, isotope, mass defect, mass number, mass spectrometer,
nuclear binding energy, unified atomic mass unit, weighted average
Prior Knowledge Questions (Do these BEFORE using the Gizmo.)
1. In the image to the right, the cans of soup have
different masses. Without doing the math,
estimate the average mass of a can of soup.
Estimate: 200g
2. Now calculate the average mass by adding up the masses of all the cans and dividing by the
total number of cans.
A. What is the average mass of a can of soup? 200g
B. How close was your prediction? Spot on
Gizmo Warm-up
Just like cans of soup, atoms of the same element often
have different masses. These different varieties are called
isotopes. In the Average Atomic Mass Gizmo, you will
learn how to find the average mass of an element using an
instrument called a mass spectrometer.
To begin, check that Carbon is selected and the Isotope
mix is Custom. Use the sliders to add about 20 atoms
each of Carbon-12 and Carbon-13 to the chamber.
1. In the mass spectrometer, atoms are vaporized (turned into a gas) and ionized (stripped of
electrons). The charged particles are then shot through a tube surrounded by
electromagnets. Click Release atoms and observe the particles as they hit the detector.
A. Do the ions travel in a straight path or a curved path? Curved
B. Which atoms are deflected the most by the magnetic field? Carbon-12
2. What is the relationship between the amount of deflection and the mass of the isotope?
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