Student Exploration: Moles
Vocabulary: atomic mass, Avogadro constant, conversion factor, dimensional analysis, mole,
molar mass, molecular mass,
... [Show More] scientific notation, significant figures, unified atomic mass unit
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? 12
2. Would a dozen of each object have the same mass? no
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.
No, just because they have the same quantity doesn’t mean they weigh the same.
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? 63.546u
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.)
E
How many atoms did you need to add? 10232019
Introduction: Since atoms are so tiny, chemists have devised a unit known as the mole. A mole
represents a macroscopic quantity of matter that can be used in the laboratory. One mole of any
element has the same mass in grams as its atomic mass in u.
Question: How many particles are in a mole?
1. Explore: Note the average atomic mass of copper on the nano-balance. Add atoms to the
larger balance until it registers the same number (in g) as the reading on the nano-balance
(in u). Use the Exponent slider to help get the correct amount. Stop adding atoms when the
readings on both balances match exactly (to the nearest 0.001 g).
How many atoms did you need to add? [Show Less]