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Introduction to the Mole

Lesson Plan

Introduction to the Mole


In this lesson, students learn why and how the mole is used in chemistry. Students will:

  • calculate the formula weights of various compounds.
  • apply the mole concept to representative particles by determining the mass of atoms, molecules, ions, and formula units.
  • perform mass-mole conversions.
  • conduct a laboratory activity to calculate and determine if a mole of pennies would fit inside the classroom.

Essential Questions


  • Atomic Mass: The mass in atomic mass units (amu) of one mole of a substance.
  • Conversion Factor: A ratio equal to one that expresses the same quantity in two different ways.
  • Formula Unit: The representative particle of an ionic compound.
  • Formula Weight: The weight of a molecular compound or an ionic compound.
  • Gram-mole: The mass of one mole, or 6.02 × 1023 particles, expressed in grams.
  • Mole: The quantity of a substance that has a weight, measured in grams, that is numerically equal to the molecular weight of that substance. Expressed as 6.02 × 1023 particles (Avogadro’s number); mol is used in equations, mole is used in writing.
  • Molar Mass: The sum of all the atomic masses in a molecule or compound; the mass in grams of one mole of a substance.
  • Representative Particles: The atoms, molecules, ions, or formula units present in a substance.


90 minutes/2 class periods

Prerequisite Skills

Prerequisite Skills haven't been entered into the lesson plan.


Related Unit and Lesson Plans

Related Materials & Resources

The possible inclusion of commercial websites below is not an implied endorsement of their products, which are not free, and are not required for this lesson plan.

  • How Big Is a Mole?

  • The World of Chemistry (video on the mole concept) 

  • Mole Song (“A Mole is a Unit”)

  • Happy Mole Day to You Song

  • Table of Atomic Weights (in alphabetical order and in order of atomic number)

  • The Mole Concept (Avogadro’s Number)

  • Mole Toons (mole cartoons)

Formative Assessment

  • View
    • Assess students’ understanding of atomic mass during the warm-up activity.
    • Collect and assess the exit ticket, the Mass-Mole Conversions worksheet, and the lab handout.

Suggested Instructional Supports

  • View
    Scaffolding, Active Engagement, Modeling, Explicit Instruction
    W: This lesson is an introduction to the concept of the mole and why chemists use it. It includes mass-mole conversions and a lab activity.
    H: The lesson begins with a warm-up to activate prior knowledge on atomic mass.
    E: The first day includes a PowerPoint presentation, notes, a graphic organizer, and two worksheets. The second day is a lab activity in small groups.
    R: Students apply concepts from the PowerPoint presentation as they complete a graphic organizer and practice mole conversions on two worksheets, and then as they answer follow-up questions during the lab.
    E: Students express their understanding by applying the mole concept in mass-mole conversions and answering questions on the lab activity.
    T: This lesson can be tailored by providing additional practice with mass-mole conversions and reviewing vocabulary terms from the lesson.
    O: The lesson begins with lecture and notes through a PowerPoint presentation, then students explore the concepts on a graphic organizer and two worksheets of conversion problems, and then they apply the mole to counting pennies during a lab activity.

Instructional Procedures

  • View

    Day 1

    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 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).

    Day 2

    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, 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:
    • 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

Related Instructional Videos

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DRAFT 06/01/2011
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