Sarah L. Wood

 

Introduction to the Mole, Avogadro's Number, and Atomic Mass

 

Purpose/Rationale:

            The purpose of this lesson is to briefly assess prior knowledge and to introduce the mole concept to students following the 5-E learning model.  By participation in small group problem solving, students will discover the importance of units of measurement and conversions.  Furthermore, students will explore the history of the mole using specified online resources.

 

Standards Addressed:

CH.1    The student will investigate and understand that experiments in which variables are measured, analyzed, and evaluated produce observations and verifiable data.  Key concepts include mathematical manipulations such as dimensional analysis.

 

CH. 2   The student will investigate and understand the placement of elements on the periodic table is a function of their atomic structure.  The periodic table is a tool used for the investigations of average atomic mass, mass number, and atomic number.

 

CH. 4  The student will investigate and understand that quantities in a chemical reaction are based on molar relationships.  Key concepts include Avogadro's principle and molar volume and stoichiometric relationships.

 

NSES A Students should develop understandings about and the abilities necessary to do scientific inquiry.

 

NSES B  Students should develop an understanding of the structure of matter.

 

Materials:

student activity sheets                1 large clear, pre-weighed canister of apple jacks

student laptops                         5 medium, clear canisters of apple jacks

five balances

 

Resources: 

            Parts of this lesson were adapted from Kim Cerrudo's lesson, Bringing Perspective to the Mole which can be found on http://www.ed.mtu.edu/esmis/id61.htm .

 

Safety: 

            Standard lab safety rules should be followed.  Inform students that eating lab materials will not be tolerated. 

 

Time:

            This lesson requires two 50-minute class periods.

 

 

 

Procedure:

Engage (Day 1:  5-7 minutes)

            1.  Students will be given activity sheets as they enter the room.  The following engagement activity will be read aloud. "You are an incredibly valuable employee.  Your boss wants to reward you so she offers you two options.  You can either work 10 days straight and receive one million dollars or you can earn a dollar per second up to one million dollars.  You would like to buy an elite condo in the Bahamas that costs exactly one million dollars.  Which deal will allow you to purchase the condo first?  (Assume that you work every second of every day in both cases.)  Your boss is in a hurry to a meeting so you only have five minutes to decide."

 

            2.  After five minutes, students will discuss their decisions as a class.  The basics of dimensional analysis will be reviewed at this time.

 

Explore (Day 1:  35-40 minutes)

            1.  A large, pre-weighed clear container filled with Apple Jacks will be placed in front of the class.  Students will be asked to determine the number of Apple Jacks in the container without counting.  Guidance will be given after five to ten minutes if necessary.  Groups will compare strategies and answers after fifteen minutes.

 

            2.  Students will be asked to repeat the best strategy in determining the number of apple jacks in one of five smaller jars.

 

Explain (Day 2:  20 minutes)

            1.  The instructor will review the previous day's activities and then ask for volunteers to explain the best strategy.  Then, explanations regarding the concept of the mole, Avogadro's number and atomic mass will be given.  First, students will be asked to brainstorm measurements such as dozen, acre, etc.  Then dimensional analysis will be demonstrated using a few examples.  Finally, understanding of these will be extended to the mole.  (See IntroMoleNotes powerpoint)  To keep students engaged and to assess understanding, five bonus questions are embedded within the powerpoint.  Each question is worth one bonus point.  Notes will be placed in blackboard for students to use for the remainder of the unit.

 

            2.  The students will be instructed to explain the analogy between the weighing of apple jacks and apple jacks to the mole, Avogadro's number, and atomic mass on their activity sheets.

 

Elaborate (Day 2:  30 minutes)

            1.  The students will read explanations concerning the history and purpose of the mole and the history and nature of science using select websites.  Students will paraphrase these on their activity sheets.  The teacher will circulate throughout the room to answer any questions and clear up any confusion.

 

            2.  Students will be given seven homework problems to demonstrate their ability to identify atomic mass, molar mass, and basic mole conversions.

 

 

 

Evaluation

Performance Criteria

Evidence

0 points

1 point

2 points

Students should solve problems using dimensional analysis.

students use dimensional analysis to perform conversions

did not attempt dimensional analysis

performed dimensional analysis partially

used dimensional analysis to solve problems

Students should solve problems using solutions that mimic the mole

students create a solution to determine the number of Apple Jacks

did not attempt a solution

solution did not include the mole concept

solution included the mole concept

Students should understand and  paraphrase history of the mole

students paraphrase history of the mole

did not attempt paraphrase

submitted incorrect paraphrase

submitted correct paraphrase

Students should demonstrate understanding of the nature of science

students indicate that science is discriminate and political

did not attempt description of the nature of science

submitted incorrect description of the nature of science

submitted correct description of the nature of science

 

 

 

 

 

 

 

 

 

 

 

 

Name __________________________________ Period_____ Date_________________

 

 

 

Introduction to the Mole Concept

 

Engage:  Who Wants to be a Millionaire?  (5-7 minutes)

            You are an incredibly valuable employee.  Your boss wants to reward you so she offers you two options.  You can either work 10 days straight and receive one million dollars or you can earn a dollar per second up to one million dollars.  You would like to buy an elite condo in the Bahamas that costs exactly one million dollars.  Which deal will allow you to purchase the condo first?  (Assume that you work every second of every day in both cases.)  Your boss is in a hurry to a meeting so you only have five minutes to decide.

 

Which do you choose?  Use dimensional analysis to defend your choice.

 

 

 

 

 

 

Explore:  How Many Apple Jacks? (35-40 minutes)

            In groups of five, devise a strategy for determining the number of Apple Jacks in the container without counting them.  You may use a ruler, measuring cup, and/or balance.  In case you need to know, the mass of the empty container is FILL IN BLANK HERE.  You have fifteen minutes to complete this task.

 

Describe your strategy below.

 

 

 

 

 

 

 

 

 

 

How many apple jacks do you think are in the container?

 

 

 

Was your strategy the best strategy?  If not, describe the best strategy below.

 

 

 

In the same groups, use the best strategy from the Apple Jack activity to determine the number of apple jacks in your jar.

 

What number jar do you have?

 

 

How many apple jacks do you think are in the jar?  (Support your answer with dimensional analysis.)

 

 

 

 

 

 

 

 

Explain (20 minutes)

How does the group of Apple Jacks you weighed compare to a mole?

 

 

 

 

 

 

How does the number of Apple Jacks you weighed together compare to Avogadro's number?

 

 

 

 

 

 

 

How does the mass of the group of Apple Jacks compare to atomic mass? 

 

 

 

 

Elaborate (30 minutes)

Use these websites to answer the following questions.

http://www.bulldog.u-net.com/avogadro/avoga.html

http://chemistry.about.com/library/weekly/aa111602a.htm

 

Do you think Avogadro was a fairly wealthy man?  Why? 

 

 

 

 

Do you think his societal and/or financial status affected his science?  Explain.

 

 

 

 

 

 

 

 

 

 

Do you think science is political?  Explain.

 

 

 

 

 

 

 

 

 

What is Avogadro's number and how was it derived?

 

 

 

 

 

 

 

 

 

What is a mole?  Give one analogy that demonstrates how many particles are in one mole of a substance.

 

 

 

 

 

 

 

 

http://www.moleday.org/

What is mole day?

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Name __________________________________ Period_____ Date_________________

 

 

 

Atomic Mass, Molar Mass, and Avogadro's Number Homework

 

 

For each of the following, calculate the atomic mass.  Round to two decimal places and don't forget your units!

 

1.)  What is the atomic mass of Xe?

 

 

 

 

2.)  What is the atomic mass of Potassium?

 

 

 

 

3.)  What is the molar mass of pure Carbon?

 

 

 

 

4.)  What is the molar mass of pure Aluminum?

 

 

 

 

 

5.)  Does one mole of every element equal the same mass?

 

 

 

 

6.)  What is the mass in grams of 3.50 mol of the element copper?

 

 

 

 

 

 

 

7.)  How many moles of silver are in 3.01 x 1023 atoms of silver?