Prior Knowledge Questions ​(Do these BEFORE using the Gizmo.)
1. In the image to the right, note a dozen eggs, a dozen donuts and a dozen roses.
How many of each item do you have?
2. Would a dozen of each object have the same mass?
3. Suppose you have a dozen carbon atoms, a dozen gold atoms, and a dozen iron atoms. Even though you
have the same number of each, would you expect them all to have the same mass? Explain.
Gizmo Warm-up
When counting roses, eggs, or donuts, a dozen is a good unit to use. If you are
counting atoms, however, a dozen is not much help. In the ​Moles​ Gizmo, you will learn
about a unit used to count atoms.
On the AVOGADRO CONSTANT tab, place the copper (Cu) atom on the nano-balance
on the left, which will show the average atomic mass of copper rather than the mass of
a single copper atom.
1. What is the average mass of a copper atom?
The unit “u” refers to ​unified atomic mass units​. A single proton or neutron has a mass of approximately
one atomic mass unit. (Officially, 1 u is one-twelfth the mass of a C-12 atom.)
2. To gain an idea as to how many atoms are in a gram or so of copper, use the larger balance on the right.
Press ​Add atoms​ to put a scoop of atoms in the weighing dish, and keep adding until the balance registers
between 1 and 2 grams. If you don’t seem to be making much progress, adjust the exponent using the
slider, which will make the scoop size bigger. How many atoms did you need to add?
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Name:  | Date:12
no
no just because they have the same amount doesnt mean they weigh the same