To prepare, gather materials for the Day 2 lab.
As a warm-up, have students take out their periodic tables and answer the following questions in their notes (S-C-8_Periodic Table.pdf):
1. What is the atomic mass of carbon? (12.01)
2. What does atomic mass measure? (the mass of an atom of an element)
3. What is the unit for atomic mass? (atomic mass units (amu))
Go over the answers to the warm-up activity.
As an introduction to the mole, show students slides 1–18 on the slideshow at How Big Is a Mole available from www.slideshare.net/vmizner/how-big-is-a-mole. Afterward, show students the Just How Big Is a Mole? resource (S-C-8-1_Just How Big Is a Mole.doc). Ask them to explain why a mole of popcorn seeds is larger than a mole of salt grains. Also, have them use Avogadro’s number to describe a mole of popcorn seeds and a mole of salt grains.
Show students The Mole PowerPoint Presentation (S-C-8-1_The Mole PowerPoint Presentation.pptx). Have students take notes during the PowerPoint presentation. Also, have them solve the practice problems in their notes before you reveal and explain the answers.
Provide additional practice by having students solve the following conversion problem.
How many atoms are in 2.5 moles of titanium?
moles × atoms/mole = atoms of Ti
2.5 moles × 6.02 x 1023 atoms/1 mole = 1.5 x 1024 atoms of Ti
Have a volunteer write the units only for the solution on the board, leaving room to add the numbers. Once the units are in place, have another student add the numbers. Then, solve the problem together as a class. Check that students understand how to set up conversion equations. Provide additional practice if needed.
Hand out copies of Comparing Sugar and Water (S-C-8-1_Comparing Sugar and Water and KEY.doc). Have students work in pairs to complete the table, and then go over the answers with the class.
Have students work individually to complete the Mole Concepts worksheet (S-C-8-1_Mole Concepts Worksheet and KEY.doc).
For homework, assign the Mass-Mole Conversions worksheet (S-C-8-1_Mass-Mole Conversions Worksheet and KEY.doc).
Collect the homework, the Mass-Mole Conversions Worksheet (S-C-8-1_Mass-Mole Conversions Worksheet and KEY.doc).
Hand out copies of the Lab: Would a Mole of Pennies Fit Inside our Classroom? (S-C-8-1_A Mole of Pennies Lab and KEY.doc). Explain the objective of the lab. Review the mole concept from Day 1, and discuss conversion factors if needed. Divide students into groups of four and have them complete the lab. Monitor the classroom and assist with calculations if students need support.
On an exit slip, ask students to write a sentence explaining how the mole concept is like using dozens or hours as standards. Example response: Chemists use the mole as a shortcut for measuring large amounts of particles, like we use dozens as a shortcut to measure objects or hours to measure time more easily.
Optional: Play the song “A Mole Is a Unit,” which can be found on various Web sites including www.youtube.com/watch?v=1R7NiIum2TI, to reinforce the mole concept and conclude the lesson.
- To support the solving of mass-mole problems, provide students who might need an opportunity for additional learning with a table of atomic weights that is arranged in alphabetical order, such as the one at: www.medicinescomplete.com/mc/merck/2010/AtomicWeights.pdf.
- Students who might need an opportunity for additional learning can prepare index cards with the conversion factors on them to use as they solve problems. Also, you can provide a list of the lesson’s vocabulary. Review other related terms if needed (e.g., atoms, molecules, compounds, and ions).
- During the lab, support students by walking them step-by-step through the calculations and explaining the conversion factors.
- Challenge students who may be going beyond the standards to solve the following problem: “A mole of pennies stacked end to end would reach from Earth to the Sun and back how many times?” (Almost 500 million times)
- As an extension for the lab activity, have students who might be going beyond the standards calculate about how many moles of M&M’s it would take to fill the volume of the Earth’s oceans (i.e., 1.35 ×109 km3)? (It would take about 3 moles of M&M’s®.) See calculations at www.madsci.org/posts/archives/2002-02/1013032438.Ch.r.html.