Partnering for Success
Grade 9: Physical Science
Chemistry
Summer C
Developed by:
Dr. Debbie K. Jackson
Dr. Robert Walters
Dr. William Donovan
Table of Contents
Schedule of Activities ............................................................................................................... 3
Ohio Academic Content Standards ......................................................................................... 4
Day One .................................................................................................................................... 6
Unpacking the Ohio Academic Content Standards ...................................................................... 6
Reform-Based Science Teaching..................................................................................................... 7
What’s in an Atom? ....................................................................................................................... 11
Modeling Rutherford’s Gold Foil Experiment ............................................................................ 12
Information about the Atom ......................................................................................................... 17
Isotopes ............................................................................................................................................ 18
Reflection of Activities ................................................................................................................... 28
Day Two: The Periodic Table................................................................................................ 29
Mega Mining Mart ......................................................................................................................... 29
Constructing and Deciphering a Periodic Table puzzle ............................................................. 40
Making Sense of the Periodic Table ............................................................................................. 41
Using the periodic table to make predictions............................................................................... 42
Reflection of Activities ................................................................................................................... 47
Day Three: Chemical Bonding.............................................................................................. 48
Investigating Phenomena............................................................................................................... 48
NEOCEx Lesson Plan Chemical Bonding.................................................................................... 50
Conservation of Matter.................................................................................................................. 60
Reflection of Activities ................................................................................................................... 62
Day Four: Acids and Bases ................................................................................................... 63
Acids and Bases at Home............................................................................................................... 63
The Chemistry of Hair ................................................................................................................... 66
The Acid Stomach .......................................................................................................................... 75
2
Schedule of Activities
Time
8:00 am
Morning Session
9:00 am – 12:00
pm
12:00 pm – 1:00
pm
Afternoon Session
1:00 pm – 3:30 pm
3:30 pm – 4:00 pm
Monday
Paper work:
Pretest, Graduate
credit, Viking Card,
etc.
Ohio Academic
Content Standards
Refresh: Reformbased Science
Teaching – 5E’s
Getting started with
Chemistry
Tuesday
Questions,
reflection, and
review
Wednesday
Questions,
reflection, and
review
Thursday
Questions,
reflection, and
review
Periodic table
Chemical bonds
Acids and bases
Lunch on your own
Models of an atom
Isotopes
Periodic table
continued
Chemical reactions Wrapping up
chemistry
Looking forward to
the academic year
Wrap Up/ Reflection/ Questions
Ohio Academic Content Standards
Grade 9
Included in Summer C
Matter
Nature of Matter
1. Recognize that all atoms of the same element contain the same number of protons, and elements with the same number of
protons may or may not have the same mass. Those with different masses (different numbers of neutrons) are called isotopes.
2. Illustrate that atoms with the same number of positively charged protons and negatively charged electrons are electrically neutral.
4. Show that when elements are listed in order according to the number of protons (called the atomic number), the repeating patterns
of physical and chemical properties identify families of elements. Recognize that the periodic table was formed as a result of the
repeating pattern of electron configurations.
5. Describe how ions are formed when an atom or a group of atoms acquire an unbalanced charge by gaining or losing one or more
electrons.
7. Show how atoms may be bonded together by losing, gaining or sharing electrons and that in a chemical reaction, the number, type
of atoms and total mass must be the same before and after the reaction (e.g., writing correct chemical formulas and writing
balanced chemical equations).
8. Demonstrate that the pH scale (0-14) is used to measure acidity and classify substances or solutions as acidic, basic, or neutral.
9. InvestIgate the properties of pure substances and mixtures (e.g., density, conductivity, hardness, properties of alloys,
superconductors and semiconductors).
10. Compare the conductivity of different materials and explain the role of electrons in the ability to conduct electricity.
Science and Technology
Understanding Technology
1. Describe means of comparing the benefits with the risks of technology and how science can inform public policy.
Abilities to Do Technological Design
2. Identify a problem or need, propose designs and choose among alternative solutions for the problem.
3. Explain why a design should be continually assessed and the ideas of the design should be tested, adapted and refined.
4
Scientific Inquiry
Doing Scientific Inquiry
1. Distinguish between observations and inferences given a scientific situation.
2. Research and apply appropriate safety precautions when designing and conducting scientific investIgations (e.g., OSHA, Material
Safety Data Sheets [MSDS], eyewash, goggles and ventilation).
3. Construct, interpret and apply physical and conceptual models that represent or explain systems, objects, events or concepts.
4. Decide what degree of precision based on the data is adequate and round off the results of calculator operations to the proper
number of significant figures to reasonably reflect those of the inputs.
5. Develop oral and written presentations using clear language, accurate data, appropriate graphs, tables, maps and available
technology.
6. Draw logical conclusions based on scientific knowledge and evidence from investIgations.
Scientific Ways of Knowing
Nature of Science
1. Comprehend that many scientific investigations require the contributions of women and men from different disciplines in and out of
science. These people study different topics, use different techniques and have different standards of evidence but share a
common purpose - to better understand a portion of our universe.
2. Illustrate that the methods and procedures used to obtain evidence must be clearly reported to enhance opportunities for further
investigations.
Ethical Practices
4. Explain how support of ethical practices in science (e.g., individual observations and confirmations, accurate reporting, peer review
and publication) are required to reduce bias.
Scientific Theories
5. Justify that scientific theories are explanations of large bodies of information and/or observations that withstand repeated testing.
6. Explain that inquiry fuels observation and experimentation that produce data that are the foundation of scientific disciplines.
Theories are explanations of these data.
7. Recognize that scientific knowledge and explanations have changed over time, almost always building on earlier knowledge.
Science and Society
8. Illustrate that much can be learned about the internal workings of science and the nature of science from the study of scientists,
their daily work and their efforts to advance scientific knowledge in their area of study.
9. InvestIgate how the knowledge, skills and interests learned in science classes apply to the careers students plan to pursue.
5
Day One
Unpacking the Ohio Academic Content Standards
Looking at the indicators we hope to address through this institute for ninth grade
science, discuss in your groups and answer the following questions:
1. Restate the indicator in your own words
2. What should students know and be able to do in order to meet this indicator?
What conceptions or misconceptions might students bring about this indicator?
3. What specific questions or activities could be done to help students to meet this
indicator?
4. Write an assessment question that students could answer to demonstrate their
mastery of this indicator.
5. Write one extended response question that would engage students in thinking
and reasoning and would help you as the teacher assess their progress toward
mastery of the indicator.
6
Reform-Based Science Teaching
Reflection Questions
From your experiences in the PFS institute, what teaching styles do you think we
advocate?
What is the learning cycle? What are the 5E’s?
What is scientific inquiry?
What value do these ideas have for your science teaching? Have they influenced your
science teaching (if so, how and if not, why not)?
7
Getting Started in Chemistry
Taken from Stop Faking It! Chemistry Basics
Materials:
Baking soda
Vinegar
Epsom salts
Metal bottle caps
Ruler
Pencil
Tongs
Wooden matches
Plastic cup
Candle
Lighter
Double pan balance
Small Glass
Directions:
1. Pour a small amount of baking soda in a clear glass or plastic cup. With the cup sitting
on the table, add about 40 mL of vinegar. Describe what happens. Use all of your
senses to make observations.
2. Light a candle and place it next to the cup. Carefully “pour” the contents of the cup onto
the candle. “Pour” is in quotes, because you are not pouring the liquid; just use a pouring
motion until something happens to the candle. Describe what happens. (as shown on
page 2).
8
3. Place one wooden match on each side of a double pan balance and check that the
balance balances. Strike a third match and lgith one of the matches sitting on the
balance on fire. Make careful observations of the burning process. Which way is the
flame directed? Does anything besides the flame seem to “leave” the match as it burns?
What about after one match completely burns? Does your balance stay in balance? If
not, which way does it tip?
4. Get another match and a small glass. Light the match and hold the glass inverted above
the match (as shown on page 3). Rub your finger on the inside of the glass. What do you
notice?
5. Pour a small pile of Epsom salts into each bottle cap, adjusting the amounts until it
balances. Remove one of the bottle caps containing Epsom salts. Using tongs so you
don’t burn your fingers, hold the bottle cap over a flame for a few minutes. What do you
notice as the Epsom salts are burning? After burning for a few minutes, let the bottle cap
cool down and return it to the balance. Which way does the balance tip? What does that
mean in terms of relative weights of the two sides?
9
Look back at your observations. Use what you know about chemistry explain what is
happening in each of the five instances.
Instance
1. Adding
vinegar to baking
soda
Explanation
2. “Pouring” the
contents onto a
candle
3. Burning a
wooden match
4. Lighting a
match under an
inverted cup
5. Burning
Epsom salts
10
What’s in an Atom?
The following activities were taken from Atomic Theory Unit developed for Cleveland Municipal
School District by Darlene Davies and John Peduzzi, May 2006
Procedure
• Take the “obscer-tainer” and record the number.
• Handle the obscer-tainer any way that will not disturb it to make any inferences about its
content.
• Write a description as well as draw what your group thinks is in the box.
• Answer the questions in the Analysis. Make a report of the conclusion about the content
of your box and your responses in the Analysis.
Data
Box number = _____________
Observations:
Analysis
What did your group think was in the box? Draw it as well as explain it.
What influenced your group’s thinking?
How did your group work out any differences of opinions of what was in the box?
Have each group member give one example of when that member uses inferences.
How does this activity relate to how scientists know what atoms and molecules look like?
11
Modeling Rutherford’s Gold Foil Experiment
Student Activity Sheet
Team Members
• Holders of gold foil (poster board) _______________________,
________________________
• Alpha Particle Thrower (tossing ball) _________________________
• Data Recorder ___________________________
Purpose
To demonstrate the reasoning used by Earnest Rutherford in determining the properties of the
nucleus.
Procedure (All Measurements are to be recorded in the Data section of this Activity Sheet.)
• Measure the length and width of the poster board (to the nearest whole cm) and record
this information.
• Measure the length and width of 1 hole (to the nearest whole cm) in the poster board
and record this information.
• Have the two holders hold the poster board straight up and down at the edge of a table
or desk.
• Have the thrower stand 2 meters from the poster board and toss the ball, underhanded
and with medium speed) at the board 20 times.
• The recorder is to count the number of tosses that pass straight through the holes and
record this information
• Repeat this procedure with the other two poster boards.
Data
Poster Board: length = ________________
width = __________________
Poster Board 1
Hole dimensions: length = ________________
Total Tosses = __________
width = __________________
Tosses that pass through = __________
Poster Board 2
Hole dimensions: length = ________________
Total Tosses = __________
width = __________________
Tosses that pass through = __________
12
Poster Board 3
Hole dimensions: length = ________________
Total Tosses = __________
width = __________________
Tosses that pass through = __________
Calculations
Finding Areas
• Find the total area of the poster boards used.
A = l x w = _______cm x _______cm = _________ cm2
• Finding the area of the “empty space” (rectangular holes) in Poster Board 1
Area of 1 hole: A = l x w = _______cm x _______cm = _________ cm2
Find total area of “empty space” in Poster Board 1: A = _________cm2
• Finding the area of the “empty space” (rectangular holes) in Poster Board 2
Area of 1 hole: A = l x w = _______cm x _______cm = _________ cm2
Find total area of “empty space” in Poster Board 2: A = _________cm2
• Finding the area of the “empty space” (rectangular holes) in Poster Board 3
Area of 1 hole: A = l x w = _______cm x _______cm = _________ cm2
Find total area of “empty space” in Poster Board 3: A = _________cm2
Finding Percentages
For each poster board, find the percentage of the board is “empty space” and the percentage of
the tosses at the board passes through the board and enter that information in the table below.
Poster
Board
% Empty
Space
% Tosses
Passed
Through
1
2
3
13
Conclusions
1. What happened to the number of tosses that passed through the poster board as the %
of the “empty space” in the board increased?
2. Does there appear to be any relationship between the % of “empty space” in the poster
board and the % of the tosses that pass through the board?
3. If the poster boards represent gold foil and the foam ball represents a positive particle,
what does this tell you about an atom?
14
Attachment A
Modeling Rutherford’s Gold Foil Experiment
Teacher Information
Teacher Preparation
Take each of the three poster board for each group and cut 4 rectangular holes in the board as
show in the diagram below. In the first board cut 4 identical rectangular-openings, each 14 cm
high and 20 cm wide; on board 2, cut 4 rectangles, each 18 cm by 23 cm; on board 3, cut 4
rectangles each 22 cm by 28 cm.
Classroom Organization
• Divide class into groups of 4. The roles in each group: 2 holders of the poster board
(gold foil), one ball thrower and one recorder
• Each group receives 1 copy of student copy of Attachment A, 3 poster boards will holes
cut, and a foam ball (alpha particle)
• Optional: hand held calculator to do the calculations
Math Review
This activity requires the students to find the area of a rectangle and to find percents. It is
suggested that you review these concepts with the students.
Finding the area of a rectangle
Remind them that the area of a rectangle is found using the following formula:
Area = length x width
A=l×w
Also remind them that the units for the area will be square centimeters (cm2).
Finding percent
In this activity, the students are asked to find the percent of the poster boards that are empty
space and what percent of the balls pass through the holes (empty space).
Remind them that to find percent, some part is divided by the whole amount and the answer is
multiplied by 100.
To find the percent of empty space, the area of the holes in the board (the area of 1 rectangle
times 4) is the part and the total area of the poster board is the whole.
15
To find the percent of the balls that pass through the holes (empty space), the part is the
number of balls that pass through the hole and the whole is the total number of balls thrown at
the poster board.
• the area of the “empty space” in the poster board.
• the number of tosses that passed through holes in the poster board.
For each situation, the value of the part and whole must be determined and then used to find
the percent in each.
Finding percent of empty space
When finding the percent of the empty space in the poster board, the part is the total area of the
four rectangular holes and the whole is the total area of the poster board. The percent of the
empty space can be determined by the following:
% of empty space = (total area of four rectangular holes ÷ total area of poster board) X 100
These values will be entered into the second column of the Table A on the Student Activity
Sheet.
Table A
Percentage Calculations
Poster
Board
% Empty
Space
% Tosses
Passed
Through
1
2
3
Finding percent of tosses that pass through poster board
When finding the percent of tosses that passed through the holes in the poster board, the part
is the number of tosses that passed through the poster board and the whole is the total number
of times the ball is tossed at the poster board (20). The percent of the tosses that pass through
the poster board can be determined by the following:
%tosses passed through = (number of tosses that pass through ÷ total number of tosses) X 100
These values will be entered into the third column of Table A on the Student Activity Sheet.
16
Information about the Atom
Fill in as much of the following table as you know.
Particle
Charge
Location
Relative Mass
Draw an atom below and label the regions and the particles. Make sure drawing includes labels
of the different components.
What is the atomic number?
What is the mass number?
17
Isotopes
(Copied from http://www.sciencenetlinks.com/lessons.cfm?BenchmarkID=4&DocID=176)
Isotopes of Pennies
Purpose
To demonstrate that isotopes of an element have different masses; that isotopes are atoms of
the same element that have different numbers of neutrons; and that atomic mass is the
weighted average of the naturally occurring isotopes of an element.
Context
This is the first in a three-lesson series about isotopes, radioactive decay, and the nucleus. The
second lesson, Radioactive Decay: a Sweet Simulation of Half-life, introduces the idea of halflife. The final lesson, Frosty the Snowman Meets His Demise: An Analogy to Carbon Dating, is
based on gathering evidence in the present and extrapolating it to the past.
This lesson helps students build their understanding of the properties of matter, specifically it
will help them understand that average atomic mass is not a simple average, but is weighted
according to percent abundance. Before working on this lesson, students should be familiar with
the periodic table and should have had some basic instruction in the following concepts:
isotopes, mass number, and atomic number. Students should be able to describe an atom and
its basic structure.
This lesson helps students understand the important notion that neutrons in the nucleus add to
an atom's mass. Prerequisite understanding for this lesson can be found at the 6-8 level,
particularly the idea that "atoms of any element are alike but different from atoms of other
elements." (4D Structure of Matter (6-8) #1) The ideas in this lesson are essential for building an
understanding of the concept that the nucleus of radioactive isotopes spontaneously decays.
Electrically neutral particles (neutrons) in the nucleus add to its mass but do not affect the
number of electrons and so have almost no effect on the atom's links to other atoms (its
chemical behavior). A block of pure carbon, for instance, is made up of two kinds, or isotopes, of
carbon atoms that differ somewhat in mass but have almost identical chemical properties.
Scientists continue to investIgate atoms and have discovered even smaller constituents of
which electrons, neutrons, and protons are made.
According to research, students may at first take isotopes to be something in addition to atoms
or as only the unusual, unstable nuclides. The most important features of isotopes (with respect
to general scientific literacy) are their nearly identical chemical behavior and their different
nuclear stabilities. Insisting on the rigorous use of isotope and nuclide is probably not
worthwhile, and the latter term can be ignored. (Benchmarks for Science Literacy, p. 79.) In this
lesson, pennies of different compositions represent isotopes. Students can readily understand
that pennies of different masses are still pennies.
18
Planning Ahead
Materials:



Isotopes of Pennies lab packets—one copy for each student
Isotopes of Pennies assessment sheet—one copy for each student
For each pair of students, you will need:
 a balance
 an empty 35 mm film canister
 six pennies made before 1982 and seven made after 1982
 a sample of ten pennies to place in the film canister
Preparation
Before the lesson, prepare the canisters in the following manner:
1. Put a piece of tape on the sides of the canisters and write a code letter on the top of
each canister. Be sure to keep a record of the code letters on a separate sheet of paper.
2. Weigh the canisters with their tops. Record the mass on the tape on the side.
3. Place a penny sample in the canister. Record the number of old and new pennies next
to the appropriate code letters on your separate sheet of paper.
4. Seal the canisters with a small amount of Superglue.
Note: These sealed canisters may be kept from year to year.
Engage
Refer students to the Pictorial Periodic Table. If students are working offline, they can look at
the periodic table in their textbooks or you can print out a copy of the Web Elements: Printable
Periodic Table for them to use.
As students look at the periodic table, ask them if they see any masses that are whole numbers.
Then ask them: Why do all the atomic masses on the periodic table include decimal points
instead of just whole numbers? Accept all answers and ask students to record their answers to
this question in their science journals. Later in the lesson, students will revise their answers.
Tell students: "Since the mass number is the number of protons plus neutrons, you would
expect it to be a whole number. However, most periodic tables indicate mass number with a
small decimal component. This is the result of the occurrence of small numbers of isotopes in
any sample."
Display a "collection of atoms" such as a beaker of a solution or a glass of milk. Ask students: In
this collection of atoms, are all the atoms of a given element exactly the same? Let them explain
that isotopes of an element have the same chemical properties but different weights.
19
Explore
Tell students: "In 1913, T. W. Richards found two atomic masses for lead. In 1919, F. W. Aston
separated neon atoms into two different isotopes, after he invented the mass spectrograph.
Since that time, many isotopes of the elements have been discovered. They are all listed in
many places, including the websites used in this lesson."
Remind students that ALL atoms are isotopes. Naturally occurring chemical elements are
usually mixtures of isotopes, and so their atomic masses are weighted averages of the masses
of the isotopes in the mixture.
Distribute the Science NetLinks lab packet, Isotopes of Pennies, to each student. You may
group students in any size group, but working in pairs involves and engages each student.
Tell students: "In this activity, you will find weighted averages of the masses of two kinds of
pennies. Then you will find the number of each type of penny in your mystery sample, using the
concepts you developed in the activity."
On the first page of the lab packet, ask students to define the following terms in their own words:
isotopes, mass number, and atomic number. At the end of the lesson, students will be asked to
reflect upon and revise, if needed, these definitions. You may wish to collect these sheets to
check for student understanding. If students appear to need more instruction on isotopes, you
should review these concepts before proceeding with the lab.
Students should be able to complete parts A, B, and C in one class period. You can assign the
Isotopes of Pennies assessment sheet as homework.
Extend
Aston, Francis William - 1922 Nobel Biography
(http://nobelprize.org/nobel_prizes/chemistry/laureates/1922/aston-bio.html) , on the Nobel
eMuseum website, provides information about Francis William Aston, the British chemist and
physicist who won the 1922 Nobel Prize in Chemistry for discovering isotopes of elements by
means of the mass spectrograph.
Students can browse the website Pictorial Periodic Table to see the chart of all the elements
and every known isotope.
On the Isotopes Project Homepage (http://isotopes.lbl.gov/ip.html), students can peruse the
tables, resources, and glossary used by this nuclear radioactivity research group at the
Lawrence Berkeley National Lab. They can find a glossary and see animations of some terms
related to isotopes.
20
Evaluate
Have students complete Isotopes of Pennies assessment sheet so that you can assess student
understanding of the concepts in this lesson. In the first part of the assessment, students apply
what they have learned to various elements. Also, they write a short summary explaining how
the lab has illustrated the concepts of isotopes, mass number, and atomic number.
Have students refer back to their answers to the question in the motivation. (Why do all the
atomic masses on the periodic table include decimal points instead of just whole numbers?) Ask
them to revise or expand upon their answers based on what they have learned in this lesson.
21
Isotopes of Pennies
Lab Sheet
Science NetLinks Lab Sheet – Isotopes of Pennies
All rights reserved. Science NetLinks Student Sheets may be reproduced for educational
purposes.
You will do a lab that will deal with isotopes, mass number, and atomic mass. Before you
begin your work in the lab, try to explain these terms in your own words. After you have
finished the lab, you will have a chance to revise your explanations based on what you
have learned in the activity.
Isotope
______________________________________________________________________
______________________________________________________________________
______________________________________________________________________
______________________________________________________________________
______________________________________________________________________
Mass number
______________________________________________________________________
______________________________________________________________________
______________________________________________________________________
______________________________________________________________________
______________________________________________________________________
Atomic mass
______________________________________________________________________
______________________________________________________________________
______________________________________________________________________
______________________________________________________________________
______________________________________________________________________
22
Isotopes of Pennies
Lab Sheet
Science NetLinks Lab Sheet – Isotopes of Pennies
All rights reserved. Science NetLinks Student Sheets may be reproduced for educational
purposes.
In 1982, the United States government changed the way it minted pennies. Before 1982,
pennies were made of 95% copper and 5% tin. Now they are made of zinc coated with
copper. Because they weigh different amounts (have different masses), we can call them
isotopes of pennies.
What do the two kinds of pennies represent in this exercise?
How do the pennies differ? How do isotopes differ?
What do the pennies have in common? What do isotopes have in common?
23
Isotopes of Pennies
Lab Sheet
Science NetLinks Lab Sheet – Isotopes of Pennies
All rights reserved. Science NetLinks Student Sheets may be reproduced for educational
purposes.
Part A
1. Obtain a sample of ten pennies.
2. Weigh several pre-1982 (old) pennies and record their average mass. ______g
3. Weigh several post-1982 (new) pennies and record their average mass. ______g
4. Calculate how much three old pennies plus seven new pennies should weigh. ______g
5. Divide your answer for number 4 to find the weighted average mass of the pennies in the
sample containing three old plus seven new pennies. ______g
6. Now weigh your sample of three old and seven new pennies. Record the mass. ______g
7. Divide your answer for number six by ten to find the average mass of a penny in your sample.
______g
Compare your answer for number five to your answer for number seven. Is the weighted
average mass closer to the mass of an old penny or a new penny? Why?
How is this weighted average mass related to atomic mass?
24
Isotopes of Pennies
Lab Sheet
Science NetLinks Lab Sheet – Isotopes of Pennies
All rights reserved. Science NetLinks Student Sheets may be reproduced for educational
purposes.
Part B
1. Obtain a sample containing six old pennies and four new pennies.
2. Using the mass of an old penny and a new penny from part A above, calculate a weighted
average mass for this sample of pennies. You need to find the mass of all ten pennies and
divide by ten to find the weighted average mass. ______g
3. Now weigh your sample of pennies. Record the mass. ______g
4. Divide the mass of your sample of ten pennies by ten to find the actual average mass of a
penny in this sample. ______g
Compare your answer from number two to your answer for number four. Is the weighted
average mass closer to the mass of an old penny or a new penny? Why?
25
Isotopes of Pennies
Lab Sheet
Science NetLinks Lab Sheet – Isotopes of Pennies
All rights reserved. Science NetLinks Student Sheets may be reproduced for educational
purposes.
Part C: The Mystery Sample
1. Return your sample of ten pennies from part B to your teacher. Get a canister of pennies.
Don’t open it. Record its identifying number or letter:______
2. Record the mass of the empty film canister, which is on the label of the canister. ______g
3. Weigh the sealed film canister containing ten mixed pennies. ______g
4. Return the canister to your teacher.
Calculations:
Calculate the number of old and new pennies in your canister:
Since the total number of pennies is ten, we can say that there are x old pennies plus 10 –x new
pennies. The total mass of the pennies (canister with pennies minus the mass of the canister) is
useful here.
X times the average mass of an old penny plus (10 – x) times the average mass of a new penny
equals the total mass of the pennies in the canister. Set up an equation and solve for x. Then
you will know how many old pennies are in your canister. Subtract that number from ten to find
the number of new pennies that are in your canister.
Show your math here:
How many old pennies do you have? ______
How many new pennies do you have? ______
What percentage of old and new pennies do you have?
26
Science NetLinks Assessment Sheet – Isotopes of Pennies
All rights reserved. Science NetLinks Student Sheets may be reproduced for educational
purposes.
Isotopes of Pennies
Assessment Sheet
Applying What You Have Learned:
Calculate the average mass of potassium if the abundance and atomic masses making up its
naturally occurring samples are:
Potassium-39 93.12% 38.964
Potassium-41 6.88% 40.962
Calculate the average mass of magnesium if the abundance and atomic masses making up its
naturally occurring samples are:
Magnesium –24 78.70% 23.985
Magnesium –25 10.13% 24.968
Magnesium –26 11.17% 25.983
The atomic mass of copper is 63.540 amu. It is composed of two isotopes, Cu-63 and Cu- 65,
with atomic masses of 62.930 and 64.928 respectively. What is the relative abundance (%) of
these isotopes in naturally occurring samples of copper?
What is the difference between mass number and atomic mass?
Write a short summary explaining how this lab illustrates the concepts that you tried to explain
at the beginning of the lab. Have your explanations changed? If so, explain how.
27
Reflection of Activities
5E Unit
Engage: What’s in an atom?
Explore: Modeling Rutherford’s Gold Foil Experiment
Explain: Information about the atom
Extend: Isotopes of Pennies
Evaluation: Occurred throughout
28
Day Two: The Periodic Table
Mega Mining Mart
Taken from: http://www.eng.uc.edu/STEP/activities/descriptions/mega_mining_mart.htm
Authors
Michelle Daniel
Bartley Richardson
Duration
70 minutes (one class block)
Rationale (How this relates to engineering)
This activity will provide students with an introduction to Data Mining and Software Engineering
and their relation to the design of grocery store layouts.
Activity Summary
General Description
This introductory lesson to Chapter 2 (The Periodic Table) of the Active Chemistry text gives
students a hands-on practical experience with organizing; identify trends and understanding
correlations, in reference to a grocery store. Student will then relate the arrangement of items in
their “mega mining mart” to the arrangement of elements in the periodic table. Student’s prior
learning includes knowledge about elements, compounds, states of matter, chemical and
physical changes and density. This lesson will be made relevant to student’s lives not only by
revolving around a grocery store, a place most of them are familiar with, but also with a new
industry called Data Mining. Data Mining is performed by software engineers, who use such
things as the “Giant Eagle Plus” card to track what people are buying in grocery stores in order
to determine how to increase sales.
Teaching Philosophy
This lesson was designed as a replacement for the introductory lesson to Chapter 2 (The
Periodic Table) of the Active Chemistry textbook. To that end, we used the main ideas and
concepts from the lesson as a starting point and sought to add in engineering applications. The
basic teaching philosophy for this lesson is to give students introductory information on Software
Engineering and data mining, explain the activity to them, and then have them apply the
principles mentioned to their store layout. The teacher needs to supervise the design phase of
the activity to ensure students have an adequate grasp of the required information. This
information will prove essential when students are asked to answer the Chemistry To Go
questions at the end of the activity.
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Objectives
1. Students will explore a state-of-the-art data storage technology known as Data Mining.
2. Students will understand how Data Mining impacts society.
3. Students will apply the methods of inventive problem solving to plan the arrangement of
a store using their personal knowledge of grocery stores and the data mining
relationships provided to them.
4. Students will analyze trends in the arrangement of their “Mega Mining Mart.”
5. Students will relate the arrangement of the items in the store to the arrangement of
elements in the periodic table.
6. Students will recognize that the periodic table was formed as a result of the repeating
pattern of electron configurations and similar chemical and physical properties.
Standards
Science
• Standard: Physical Sciences
Students demonstrate an understanding of the composition of physical systems and the
concepts and principles that describe and predict physical interactions and events in the natural
world. This includes demonstrating an understanding of the structure and properties of matter,
the properties of materials and objects, chemical reactions and the conservation of matter. In
addition, it includes understanding the nature, transfer and conservation of energy; motion and
the forces affecting motion; and the nature of waves and interactions of matter and energy.
Students demonstrate an understanding of the historical perspectives, scientific approaches and
emerging scientific issues associated with the physical sciences.
Benchmark A: Describe that matter is made of minute particles called atoms
and atoms are comprised of even smaller components. Explain the structure and
properties of atoms.
o Indicator 4 (Grade 9): Show that when elements are listed in order according to
the number of protons (called the atomic number), the repeating patterns of
physical and chemical properties identifying families of elements. Recognize that
the periodic table was formed as a result of the repeating pattern of electron
configurations.
Standard: Science and Technology
o
•
Students recognize that science and technology are interconnected and that using technology
involves assessment of the benefits, risks and costs. Students should build scientific and
technological knowledge, as well as the skill required to design and construct devices. In
addition, they should develop the processes to solve problems and understand that problems
may be solved in several ways.
o
o
Benchmark B: Explain that science and technology are interdependent; each
drives the other.
Indicator 2 (Grade 10): Describe examples of scientific advances and emerging
technologies and how they impact society.
30
Technology
• Standard: Technology and Society Integration
Students recognize interactions among society, the environment and technology, and
understand technology's relationship with history. Consideration of these concepts forms a
foundation for engaging in responsible and ethical use of technology.
Benchmark A: Interpret and practice responsible citizenship relative to
technology.
o Indicator 5 (Grade 9): Provide examples of technology transfer from a
government agency to private industry, and discuss the benefits.
o Indicator 1 (Grade 10): Understand that the development of technology may be
influenced by societal opinions and demands, in addition to corporate cultures.
Standard: Technology for Productivity Application
o
•
Students use computer and multimedia resources to support their learning. Students understand
terminology, communicate technically and select the appropriate technology tool based on
their needs. They use technology tools to collaborate, plan and produce a sample product to
enhance their learning and solve problems by investIgating, troubleshooting and
experimenting using technical resources.
Benchmark A: Integrate conceptual knowledge of technology systems in
determining practical applications for learning and technical problem-solving.
o Indicator 1 (Grade 9): Explore state-of-the-art devices to store data that will be
used for researching projects.
Standard: Design
o
•
Students recognize the attributes of design; that it is purposeful, based on requirements,
systematic, iterative, creative, and provides solution and alternatives. Students explain critical
design factors and/or processed in the development, application and utilization of technology
as a key process in problem-solving. Students describe inventors and their inventions, multiple
inventions that solve the same problem, and how design has affected their community. They
apply and explain the contribution of thinking and procedural steps to create an appropriate
design and the process skills required to build a product or system. They critically evaluate a
design to address a problem of personal, societal and environmental interests. Students
systematically solve a variety of problems using different design approaches including
troubleshooting, research and development, innovation, invention and experimentation.
Benchmark A: Identify and produce a product or system using a design process,
evaluate the final solution and communicate the findings.
o Indicator 1 (Grade 9): Explain and apply the methods and tools of inventive
problem-solving to develop and produce a product or system.
Standard: Designed World
o
•
Students learn that the designed world consists of technological systems reflecting the
modifications that humans have made to the natural world to satisfy their own needs and
wants. Students understand how, through the design process, the resources: materials, tools
and machines, information, energy, capital, time and people are used in the development of
useful products and systems. Students develop a foundation of knowledge and skills through
participation in technically oriented activities for the application of technological systems.
Students demonstrate understanding, skills and proficient use of technological tools, machines,
instruments, materials and processes across technological systems in unique and/or new
contexts. Students identify and assess the historical, cultural, environmental, governmental and
economic impacts of technological systems in the designed world.
31
o
o
o
Benchmark E: Classify, demonstrate, examine and appraise information and
communication technologies.
Indicator 1 (Grade 9): Describe the careers available in information and
communication technological systems and the training needed to pursue them.
Indicator 6 (Grade 9): InvestIgate emerging (state-of-the-art) and innovative
applications of information and communication technology.
Background Knowledge
• Basic knowledge about food items and grocery store layout
Materials Required
• Mega Mining Mart Packet
o Step-by-step instructions
o Worksheets
o Career sheet
o Feedback survey
• Store Layout
• Envelope with cut-out store items
• Clear tape
Activities
When the students enter the room they will be grouped into teams of 2-3. It is best to only have
groups of 2 if resources are available to ensure that all students participate.
1. Data Mining Introduction
a. To begin class the teacher will begin class by reading the Mega Mining Mart
activity Introduction. This introduction will be read using “skip reading.” Skip
reading is when the teacher reads the introduction and stops at words in which
the students are to say that word. This way all students are forced to follow
along and actively read the intro.
b. Then the teacher will discuss Data Mining and its relation to the Mega Mining
Mart activity.
2. Software Engineering Career Sheet
a. The teacher will then direct the students’ attention to the software engineer
career sheet and relate this career to Data Mining and the Mega Mining Mart
activity.
3. Mega Mining Mart Design
a. After the discussion about software engineering and data mining, the students
will be directed to the Mega Mining Mart handout in which they will begin their
store design by spending three minutes coming up with categories for the food
items provided to them. It is important that the students only spend three
minutes or else they will not have enough time to complete the activity. Remind
students about freezer sections and refrigerator sections.
b. The students will then complete the activity by organizing their store. Students
should keep in mind their store categories as well as the data mining
associations when organizing their stores.
c. The teacher will circulate the room to ensure that all students are on task and to
make sure they are following the directions of the activity.
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d. Check Point: Students must show their final store design to the teacher to ensure
that they take into account their store categories and the data mining
associations before they are permitted to tape down the food items on their store
layout.
4. Mega Mining Mart Questions
a. After students have completed their store design they should complete the
Chemistry to Go questions.
5. Compare Mega Mining Mart to the Periodic Table
a. After the students have completed the Chemistry to Go questions, the teacher
will hold a discussion about comparisons between their store layout and the
periodic table.
b. The main point to be discussed will be the idea of trends and correlations.
Assessment of Student Learning
Student assessment will be based upon class participation, class discussion, student Mega
Mining Mart designs and their Mega Mining Mart handouts
1. Student exploration of the state-of-the-art data storage technology known as Data
Mining will be evaluated through their use of the data mining relationships in their store
design.
2. Student understanding of the impact of Data Mining on society will be assessed through
a class discussion about Data Mining.
3. Student application of the methods of inventive problem solving to plan the arrangement
of a store using their personal knowledge of grocery stores and the data mining
relationships provided to them will be assessed by their Mega Mining Mart design.
4. Student analyzing of trends in the arrangement of their Mega Mining Mart will be
assessed through their completion of the Mega Mining Mart handout.
5. Student understanding of the relationship of the arrangement of items in their store to
the arrangement of the elements in the periodic table will be assessed through class
discussion and the students Mega Mining Mart handout.
6. Student recognition that the periodic table was formed as a result of the repeating
pattern of electron configurations and similar chemical and physical properties will be
assessed through class discussion and the students Mega Mining Mart handout.
Assessment of the Activity
A student feedback form is provided with the activity. Students complete the form at the end of
the lab and give it back to the teacher. The results are compiled and used to determine the
effectiveness of the activity. In addition, the teacher will be watching the students while they
complete the activity in order to gauge their interest.
33
The Mega Mining Mart
INTRODUCTION
Most supermarkets today sell many different products. If you’ve ever been in Giant Eagle or
Acme, you know that they sell everything from milk and bread to hair dye and toilet paper. What
you may not have thought about before is how all those products are arranged in your local
supermarket. Companies like Giant Eagle spend a lot of money to find the best store layout the one that will make them the most money.
In deciding on a good (profitable) store layout, Giant Eagle often uses a technique called data
mining. Data mining was created by computer and software engineers as a way of discovering
new information from an already existing database. (A database is just a collection of
information organized in a specific way.) Take Giant Eagle for example. Whenever you use your
“Giant Eagle Advantave” card, Giant Eagle stores information on all the items you just
purchased. So if you go to the store on Monday and buy eggs, milk, and bread, Giant Eagle will
know that “customer Joe Smith purchased eggs, milk, and bread together on Monday, February
28, 2005.” Once Giant Eagle has a lot of this type of data (and it doesn’t take them long), they
can start making connections. They may find that people who buy peanut butter always buy
some kind of jelly, and these same people may buy bread at the same time. When they have
this information, they can arrange their store to maximize their profits. If people always buy
peanut butter and jelly together, Giant Eagle will put them next to each other in the aisle hoping more people will buy both items.
In this activity, you will be arranging the layout of your own store. You will be given a list of items
you want to sell, and you will have results of data mining (called data mining associations).
These associations should be used to help you arrange your store.
GOALS
In this activity, you will:
• Plan the arrangement of the items for sale in a store.
• Use data mining results to help arrange your store.
• Analyze trends in the arrangement of the store.
• Relate the arrangement of items in the store to the arrangement of elements in the periodic
table.
PROCEDURE
1. Below is a list of items you want to include in your store. (These are the same items that are
on the little pieces of green paper.) Look over this list with your group.
1. Milk
2. Bananas
3. Pepsi
4. Coke
5. Cheetos
6. Lays Potato Chips
7. Salsa
8. Tortilla Chips
9. Taco Seasoning
10. Taco Sauce
11. Bagels
12. Cream Cheese
13. Pickles
14. Lunchmeat
15. Frozen Pizza
16. Ranch Salad Dressing
17. Mayonnaise
18. Hot Sauce
19. Ice Cream
20. Diapers
21. Beer Nuts
22. Baby Food
23. Hair Dye
24. Bubble bath
25. Bleach
26. Frozen Chicken
Nuggets
27. Grape juice
28. Gatorade
29. Juice boxes
30. Hamburger
31. Hot Dogs
32. Hot Dog Buns
33. Plastic cups
34. Peanut Butter
35. Grape Jelly
36. Relish
37. Tuna
38. Frozen Pumpkin Pie
39. Kool-Aid
40. Eggs
41. Butter
42. Carrots
43. Ketchup
44. Bread
45. Pasta
46. Spaghetti Sauce
47. Toilet Bowl
Cleaner
48. Paper Towels
49. Toilet Paper
50. Disposable Latex
Gloves
34
2. You and your group should look at the list of items above and try to put all of the items into
categories. Think of larger (more general) descriptions that could apply to more than one item.
Record your categories in the space below.
3. The results of a data mining experiment are shown below. When you start planning your store
layout, you’ll need to use these associations to help you arrange some of your products. You
will also use the categories you came up with in step 2.
Data Mining Associations
1. Customers who buy Taco Seasoning also buy Toilet Paper.
2. Customers who buy Diapers also buy Beer Nuts.
3. Customers who buy Hot Dogs also buy Relish.
4. Customers who buy Frozen Chicken Nuggets also buy Hot Sauce.
5. Customers who buy Hair Dye also buy Disposable Latex Gloves.
6. Customers who buy Tuna also buy Relish.
4. Using the blank store layout and the items given to you, arrange the items into aisles in the
store. Be sure to test your layout before you glue the items down! Keep the following points
in mind when deciding on the arrangement of your items.
• What will be at the front of each aisle? What will be at the back?
• How will the store be arranged from left to right?
• What items would shoppers want to see when they enter the store?
• What items would they want to see when they’re ready to check-out?
• Did you pay attention to the data mining associations?
WHAT ABOUT THE PERIODIC TABLE?
The problem of arranging 50 items in store rows is similar to the problem Mendeleev faced
when he needed to organize chemical elements into the periodic table. The other activities in
this chapter will teach you about the properties of chemical elements that helped Mendeleev
arrange the elements the way he did. The reason you were asked to organize familiar items was
to give you a “big picture” view of the problems Mendeleev faced.
35
CHEMISTRY TO GO QUESTIONS
1. What is the pattern or arrangement in your store’s aisles? (5 pts)
2. A new item is being introduced into your store - Chocolate Mint Hershey Syrup. Where would
you place this new item in your store? Explain your decision. (5 pts)
3. Your store has decided to sell a large selection of magazines (Teen People, Cosmo, Sports
Illustrated, Jet, etc.). How would your alter your store layout to accommodate these new items?
(5 pts)
4. Market research has found that coffee sales gives your store large profits. Where would you
place coffee in your store to increase sales? Explain your decision. (5 pts)
5. One of the characteristics of Mendeleev’s original periodic table (see below) was a series of
blank spots. Since As (arsenic) and Se (selenium) didn’t have anything in common with Al
(aluminum) and Si (silicon), but do with P (phosphorous) and S (sulfur), Mendeleev decided
there must be a couple of other elements yet to be discovered. He left spaces for them and put
As under P and Se under S where they belong. What would such a “blank” correspond to in
your store? (5 pts)
36
6. Fill in the 10 blank spaces of Mendeleev’s original periodic table wit the elements they
represent (symbol and name). (5 pts)
GRADE YOUR GROUP
Grade each member in your group (including yourself) on a scale from 1 to 5. (5 pts)
5 - Excellent Group Member (worked well within the group and completed all tasks)
3 - Good Group Member (completed all tasks)
2 - Poor Group Member (did not participate)
N
37
DATA MINING FOR THE REST OF US
What is data mining?
Put into its simplest form, database mining seeks to extract previously unrecognized information
from data stored in conventional databases. Databases have significant amounts of stored
data. This data continues to grow exponentially, and much of the data is implicitly or explicitly
imprecise. There could be valuable, undiscovered relationships in the data, but the issue is how
to best recognize them. A human analyst can be overwhelmed by the large amounts of digital
information.
Database discovery (data mining) seeks to discover noteworthy, unrecognized associations
between data items stored in an existing database. The potential of discovery comes from the
realization that alternate contexts may reveal additional valuable information. A metaphor for
database discovery is “mining.” The metaphor is to somehow “sift” through the “ore” of a
database to discover information “nuggets.”
What kinds of things can data mining find?
Example 1
A classic example of data mining is the unknown association between beer and diapers.
Convenience stores (such as UDF) paid data mining companies to discover new associations in
their data. Since they keep large customer transaction databases, they wanted to know what
customers were more likely to buy if they purchase a certain product. The results showed that
the majority of customers who purchased diapers also purchased beer. While data mining
found the previously unknown association, it didn’t explain why this occurred.
After some lengthy inquiry, it was discovered that most of the people buying diapers at
convenience stores were men. Traditionally, women call their husbands (usually on the way
home from work) and ask them to pick-up diapers. Being men, most are not concerned about
price and just want to get the experience over. That being said, they usually will stop at a
convenience store to buy the diapers. (While convenient, they usually pay a premium for the
diapers.) As a reward for a “job well-done”, the men buy some beer for themselves.
After this association was found, convenience stores started placing the diapers next to the beer
cases. They saw an increase in profits.
Example 2
Most people who buy pop also purchase some kind of snack food to go with it (usually potato
chips). The company that makes Pepsi also owns the Frito-Lay Corporation (manufactures of
Lays potato chips). A major retailer sent their transaction database to a data mining firm to be
analyzed. One of the results was that people who buy Pepsi actually don’t purchase Lay’s
potato chips. In fact, people are more likely to purchase Lay’s chips if they purchase Coke
products (even though the two are different corporations).
While it may be intuitive to think that Pepsi drinkers prefer Lay’s potato chips, the opposite was
true in this case.
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Who uses data mining?
Data mining is currently most useful on large transaction databases. Major retailers like Kroger,
Wal-Mart, and Target make frequent use of data mining. The advantage of finding these
previously unknown associations is very beneficial for the retailer. If they know that people who
buy a certain product will often buy these three other products, they can price all four products
accordingly and even rearrange the store to maximize their profits.
Who does data mining?
Data mining is traditionally performed by computer and software engineers. While most
engineers have a BS degree at a minimum, some technicians who run the software will have
Associate Degrees or some limited post-secondary coursework.
Computer and software engineers are responsible for creating the algorithms that efficiently and
effectively data mine for new associations. The task of engineering new data mining techniques
can be quite lucrative, and the field still has many areas that are open for research.
What open areas for research are then in the field of data mining?
Data mining that works across multiple databases (distributed databases) is an ever-changing
and evolving field. Also, current techniques rely heavily on expert (user) knowledge during the
pre-processing phase. Techniques and software that could further automate the procedure
would be helpful.
AME GRADE
39
Constructing and Deciphering a Periodic Table puzzle
The following activities were taken from Atomic Theory Unit developed for Cleveland Municipal
School District by Darlene Davies and John Peduzzi, May 2006






Pass out a set of atomic model diagrams for first twenty elements on the modern Periodic
Table (H – Ca). Ask the teams to line them up in a continuous line. What attribute did you
choose to accomplish this?
Ask the students to observe and discuss how they can create a table using all twenty atomic
model diagrams. Let them try several ways of arranging them. Teacher should circulate
among the groups encouraging student ideas and asking open-ended questions (Any
patterns jumping out at you? What’s a table have to have? Do you see a row/column
pattern?)
Review atomic structure, attributes of fundamental atomic particles, relationship of atomic
number/ average atomic mass to particles and electron shell configuration [K=2, L=8, M=8
(18), N = 8 (32)]. Teacher should become familiar with the organization and value of the
Periodic Table
Introduce importance and relationship between valence shell, valence electrons and
Periodic Table (PT) Groups or Families (columns). PT Groups are arranged left to right
across the PT beginning with Groups I A (1) to Group VIII A (18). Give each team a set of
Group titles (Attachment C) to place above their atomic model diagrams to identify each
Group. Teacher note: Keeping in mind that the groups in the middle of the actual periodic
table – the Transition Elements – are missing here. All atoms/elements in a given Group
exhibit the same number of valence electrons, thus Group IIA (2) elements each have 2
electrons in their outermost (valence) shell and Group VIA (16) elements each have 6
electrons in their outermost (valence) shell. The number of valence electrons present in an
element’s valence shell indicates its chemical reactivity and physical behavior. Group VIIIA
(18) has a completed valence shell of eight electrons and therefore is un-reactive
(chemically stable) or “inert.”
In looking at the rows or periods each team has created ask students to identify the pattern each row has a specific number of electron shells. Beginning at the top > bottom there are
seven periods and they vary in the number of elements present. Give student teams a set
of Period titles to place on the left side of their atomic model diagram arrangement. Their
periodic table is beginning to take shape.
Using what students have just gleamed from the placement of the atomic model diagrams
move them to the next step – identify the elements associated with the atomic model
diagrams. Hand each team a set of Element cards and have them match them to the
atomic model diagrams by their atomic number (protons), number of valence electrons and
number of electron shells. Teacher should move around the classroom to make sure that all
team members are participating in this activity (maybe hand 5 different elements to each
student to place and be prepared to tell you why they placed their cards where they did on
top of the atomic model diagrams). Have one student with the blank Periodic Table diagram
fill in the atomic number and element symbol from their periodic table arrangement.
 Ask students to describe the basic trends in the table’s groups and periods.
40
Making Sense of the Periodic Table
 Using their constructed periodic tables have different members of each team answer the
following questions in their own words:
- In arranging the atomic model diagrams by periods, how did you know where to place Neon
and Potassium?
- Once you placed the atomic model diagrams in their correct periods (rows) did they
automatically line up correctly by groups (columns)? Explain what needed to happen.
- Describe the position of the following elements in your table and why they hold this position –
Carbon, Sodium, Argon, Calcium, Hydrogen, Helium, Aluminum, Nitrogen, Chlorine, Sulfur.
- (Teacher hands each team 2-3 additional atomic model diagrams- see Attachment A) Where
should these atoms be placed in your periodic table and why?
P = 31 Gallium (period 4; group III A)
P = 33 Arsenic (period 4; group V A)
P = 35 Bromine (period 4; group VII A)
P = 38 Strontium (period 5; group II A)
P = 53 Iodine (period 5; group VII A)
P = 56 Barium (period 6; group II A)
P = 82 Lead (period 6; group IV A)
P = 86 Radon (period 6; group VIII A)
P = 87 Francium (period 7; group I A)
- Where are the valence electrons found?
- Of what importance is the atom’s valence shell?
- Where are the most chemically reactive elements found in the periodic table? Where are the
least chemically reactive elements found in the periodic table? How do you know this?
- What pattern or trend do you see in the element’s atomic mass in your periodic table?
- Have we discovered all the elements in the Periodic Table?
Why or why not?
Give the students a periodic table which has the electron configuration printed in each element
box.
 Have the students look at the electron configurations of the group 1 elements and ask,
“What do the electron configurations of this group of elements have in common?" (Students
should notice that the number of electrons in the outer shell is the same).
 Explain to the students that these outer shell electrons are called the valence shell and they
primarily determine the chemical and physical behavior of elements.
 Have students complete a chart (See Attachment B, Valence Chart) in which they make
note of the number of valence electrons in all of the representative groups of elements,
groups 1, 2, 13, 14, 15, 16, 17, 18 (also known as groups IA, IIA, IIIA, IVA, VA, VIA, VIIA,
VIIIA).
41
Using the periodic table to make predictions
These activities are taken from the Ohio Department of Education, Instructional Management
System Lesson Plans (https://ims.ode.state.oh.us/ODE/IMS/Search/GSASearchResults.asp)
1. Perform a series of demonstrations using the elements of groups one and two to show the
chemical reactivity of families of elements.
a. Place small pea-sized samples of each of the elements lithium, potassium and sodium in
separate beakers of water.
b. Have students make observations about the activity.
c. Ask students questions such as:
• What evidences of a chemical reaction did you observe?
• Which element reacted the most vigorously with water?
• What is the trend for chemical reactivity of the group one elements with water?
Instructional Tip:
Use extreme caution when working with the alkali metals. Use very small pieces in large
beakers of water. Cover the beakers with heavy watch glasses immediately after dropping in the
pieces of metal. Wear personal protective safety equipment and use a shield between the
reaction and the students. Consult science supply-house catalogs for videos or CD-ROMS that
may be substituted for these demonstrations.
2. Place pea-sized samples of the elements calcium and magnesium in water. Again, have
students make observations.
3. Ask questions such as:
a. What evidences of a chemical reaction did you observe?
b. Which element reacted the most vigorously with water?
c. What is the trend for chemical reactivity of group two elements with water?
4. Show a video or CD-ROM clip of a demonstration in which the elements from groups one
and two are placed in diluted (one molar) hydrochloric acid. Have the students make
observations about the activity.
5. Ask questions such as:
• What evidences of a chemical reaction did you observe?
• Which element reacted the most vigorously with the acid?
• What is the trend for chemical reactivity of group one elements with hydrochloric acid?
• With group two elements?
• Is there a general trend in chemical reactivity for the group one and group two elements?
If so, what is it?
Instructional Tip:
It is dangerous to perform these demonstrations yourself; however, the reaction of magnesium
and hydrochloric acid can be demonstrated if proper safety procedures are followed (wear
goggles, apron and possibly gloves and use a safety shield).
6. Give students a table of atomic radii for the group one (IA or alkali metal) elements to study
a physical property of a family of elements. See the table below.
42
7. Have students construct a graph of atomic number (x-axis) versus atomic radius (y-axis),
using the atomic radii table as a reference,
Element
Atomic Number
Atomic Radius
(Angstroms)
Cesium
55
2.67
Francium
87
2.7
Lithium
3
1.55
Potassium
19
2.35
Sodium
11
1.90
Instructional Tip:
As a variation, have some students make a bar graph and have other students make a line
graph with the data. Ask them which one is more appropriate for these data and why.
8. Ask students to explain what trends are noticed on the graph curve and, in general, where
these elements are located on the periodic table. Also, have students explain whether these
elements make up a period or a group, what the relationship is between these elements and
their electron configurations, and how a missing value might be predicted. Have students
comment on how accurate such a prediction might be.
9. Give students a table of atomic radii values for the period 2 (group IIA or the alkaline Earth)
elements and have them construct a graph of the atomic number (x-axis) versus atomic
radius (y-axis).
Element
Beryllium
Boron
Carbon
Fluorine
Lithium
Neon
Nitrogen
Oxygen
Atomic Number
4
5
6
9
3
10
7
8
Atomic Radii
(Angstroms)
1.12
0.98
0.91
0.57
1.53
0.51
0.92
0.65
10. Ask students to discuss any trend that the curve of the graph shows, where these elements
are located on the periodic table, and whether these elements make up a group or a period
of elements. Ask the students to explain what the relationship is between these elements
and their electron configurations and how a missing value might be predicted. Have
students comment on how accurate such a prediction might be.
43
Periodic Table Review
List five things you learned about the periodic table through these activities.
Add to your list from the class discussion.
44
Teacher Resource Information on the Periodic Table
One way to look at the modern Periodic Table is as a structure that correlates trends in
chemical behaviors and physical properties of elements given the electronic structure of each
element’s atoms.
One way of dividing up the table is into its Main Group Elements [I A (1), IIA (2) then IIIA (13) VIIIA (18)] and the Transition Metals (1B – VIII B not in sequential order; columns 3-12).
The periodic table’s horizontal rows are called periods and the table’s vertical columns are
known as groups or families. The modern Periodic Table is arranged according to the atomic
number.
Periods
 The periods are of varying lengths. First is the hydrogen period – Period 1 – consisting of
two elements, hydrogen and helium. Then there are two periods of eight elements (Lithium
> Neon & Sodium > Argon). There follows two periods of 18 elements each (Potassium >
Krypton & Rubidium > Xenon). Finally, the longest two periods of 32 elements each,
beginning with Cesium and Francium are usually condensed to 18 with the Lanthanide
Series and Actinide Series separated out and listed below the main table.
 There are seven main periods in the modern periodic table each row identifying the number
of electron shells/orbitals present for each element’s atomic structure.
 By looking at the period that the element is found in, you can predict the valence shell
configuration fairly accurately.
 Moving left > right across a period, the atomic number increases, i.e., more protons in the
nucleus. Therefore there is a greater force of attraction between the nucleus and the
valence electrons. This is called electronegativity.
 The electrons are arranged in energy levels or shells (orbitals) around the nucleus and with
increasing distance from the nucleus. Each electron in an atom is in a particular energy level
(or shell) and the electrons must occupy the lowest available energy level (or shell) available
nearest the nucleus. When the level is full, the next electron goes into the next highest level
(shell) available.
 There are rules about the maximum number of electrons allowed in each shell. 1st shell (k
shell)has a maximum of two electrons and is closest to the nucleus, the 2nd shell (L shell)
has a maximum of 8 electrons, the 3rd shell (M shell) and 4th shell (N shell) have a maximum
of 8 electrons only up to atomic number 20, then it becomes 18 electrons after that. We are
only concerned in this lesson with the first 20 elements to focus student attention on the
basic structure of the Periodic Table.
 Since the atomic number equals both the number of protons and the number of electrons in
a neutral atom then the number of electrons in each shell can easily be determined for the
first 20 elements.
Ex. Chlorine has an atomic number of 17, therefore it has 17 protons and electrons
K shell = 2 electrons
L shell = 8 electrons
M shell = 7 electrons (this is the outermost shell = valence shell therefore these are 7
valence electrons)
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Groups or Families
 Group is a vertical column of chemically and physically similar elements. The group number
(II A) tells you there are two valence electrons the atoms outermost shell. In this Atomic
Theory Unit we are going to focus on the Groups I A (1), II A (2) and III A (13) through VIII A
(18).
 When an atom has its outer shell full (with the maximum number of electrons allowed, the
atom is said to be electronically stable and is very un-reactive. This identifies the elements
in Group VIII A and is known as the Noble Gases.
 The other Groups or Families have been given names that characterized their common
chemical and physical similarities. Going left > right they are alkali metals, alkaline earth
metals, transition metals, III A – VI A are sometimes referred to as the metalloids because
they exhibit properties of both metals and nonmetals in varying amounts, next are the
halogens and finally, the noble gases.
 Hydrogen and Helium are special elements. Hydrogen can be associated with two groups –
I A and VII A. Helium is different from all other elements because it can only have two
electrons in its outermost shell. Even though it only has two valence electrons it is in Group
VIII A because its outer shell is full and it is considered electronically stable.
 Interestingly as you move down in a group of elements the nuclear charge is increasing and
in addition, as you move downward the valence shell is moving farther away from the
positive nucleus. What effect does this have on atoms toward the bottom of the group or
family? Even though the nuclear charge is increasing as you move downward there are
more electrons between the valence electrons (outermost) and the nucleus, therefore, these
inner electrons shield the valence electrons from the attractive influence of the positive
nucleus thus the energy needed to remove a valence electron decreases.
Generally speaking, there are noticeable trends as you proceed toward the left in a period or as
you proceed down within a group:
1. The metallic strengths increase and nonmetallic strengths decrease.
2. The atomic radius of atoms (distance from the nucleus to outermost occupied regions)
increases.
3. The ionization potential energy (energy required to remove and electron from the atom)
decreases.
4. The electronegativity (electron attracting ability of an atom) decreases.
46
Reflection of Activities
5E Unit
Engage:
Explore:
Explain:
Extend:
Evaluation: Occurred throughout
47
Day Three: Chemical Bonding
Investigating Phenomena
1. You will need a light bulb from a flashlight, a 1.5 volt battery, three wires about 30 cm in
length, and some masking tape. You are making the contraption on pg. 16 of (Stop
Faking It!: Chemistry Basics). Once you have created this, place the two open ends into
a glass of water. Does the water conduct electricity? How do you know?
2. Dissolve a bunch of salt in the water. Test the saltwater to see if it conducts electricity.
What do you think is going on?
3.
a.
b.
c.
Using the Stop Faking It! Book, pgs. 60-63, answer the following:
What is an ion?
What is an ionic bond?
What is a covalent bond?
4. Blow up a balloon and tie it off. Put the balloon next to a stream of running water. Notice
anything?
5. Rub the balloon on your hair or a sweater, then put the balloon next to a stream of
running water. Notice anything? What do you think is going on?
48
6. 6. Using the Stop Faking It! Book, pgs. 63-69, answer the following:
a. What is a polar covalent bond?
b. What is a nonpolar covalent bond?
c. What is electronegativity?
d. What is the significance of a sea of electrons?
49
NEOCEx Lesson Plan Chemical Bonding
This activity was developed as a part of activities funded by the Northeast Ohio Center of
Excellence for Mathematics and Science Education
Course: Chemistry
Students:
High School/Introductory College Chemistry Students
Prepared by: Diana Williams
Date Developed:
August 2005
Last Updated:
August 2006
Concepts and Objectives: Chemical Bonding
Primary: Students will demonstrate an understanding of the chemical and physical properties
of different types of chemical bonds, including ionic, covalent, metallic, and network covalent
bonds.
Supporting: Students will develop an understanding of the structure and properties of matter,
the properties of materials and objects, chemical reactions and the conservation of matter.
Specific Learning Objectives: Students will
1. Describe the formation of the different types of chemical bonds.
2. Compare and contrast the physical characteristics of chemical bonds
3. Predict the type of bonding in compounds given physical characteristics.
Standards:
National:
Physical Science CONTENT STANDARD B: As a result of their activities in grades 9-12, all
students should develop an understanding of
•
•
•
•
•
•
Structure of atoms
Structure and properties of matter
Chemical reactions
Motions and forces
Conservation of energy and increase in disorder
Interactions of energy and matter
State: Ohio
Physical Science: Students demonstrate an understanding of the composition of physical
systems and the concepts and principles that describe and predict physical interactions and
events in the natural world. This includes demonstrating an understanding of the structure and
properties of matter, the properties of materials and objects, chemical reactions and the
conservation of matter. In addition, it includes understanding the nature, transfer and
conservation of energy; motion and the forces affecting motion; and the nature of waves and
interactions of matter and energy. Students demonstrate an understanding of the historical
perspectives, scientific approaches and emerging scientific issues associated with the physical
sciences.
50
Grade 9: Nature of Matter
Benchmark B. Explain how atoms react with each other to form other substances and how
molecules react with each other or other atoms to form even different substances.
6. Explain that the electric force between the nucleus and the electrons hold an atom
together. Relate that on a larger scale, electric forces hold solid and liquid materials
together (e.g., salt crystals and water).
7. Show how atoms may be bonded together by losing, gaining or sharing electrons and
that in a chemical reaction, the number, type of atoms and total mass must be the same
before and after the reaction (e.g., writing correct chemical formulas and writing
balanced chemical equations).
Common Student Misconceptions
•
•
•
•
•
"Bonding must be either ionic or covalent." It is a common student misconception
that a bond between two atoms, A-B, is either purely covalent or purely ionic. No
compound is 100% ionic. The best way to teach bonding is to show that there is a
gradual progression from 100% pure covalent bond (homonuclear) to one that is about
98% ionic.
“Molecules are glued together”: forces of attraction hold molecules together, not glue.
"Covalent bonds must be weak because covalent compounds are generally soft
with low melting points (< 300 ∞C)." Actually, this is a case of confusing
intermolecular with intramolecular bonding.
“The chemical bond is a physical thing made of matter”: Chemical bonds are not
made of a separate form of matter, but the electrons that are shared and forces of
attraction.
“Electrons know which atom they came from”: There are not different kinds of
electrons for different atoms. Atoms do not "possess" their specific electrons. Electrons
are the same and can be transferred from one atom to another.
Prior Knowledge: Students should have a good understanding of atomic theory and periodicity.
Pre-Assessment: Check student understanding with an informal activity. Show bonding table
(appendix 1) and ask students to identify the areas they already understand.
51
Lab: Comparing Physical Properties to Bond Types
Experiment adapted from savitapall.com
Introduction
Solid crystals consist of a regular array of particles located at the lattice points in a threedimensional lattice work. A compound is defined as the chemical combination of two or more
elements. A chemical bond is the "glue" that holds atoms of different elements together. Bonds
can be classified into two general types: ionic and covalent.
The units which occupy the lattice points in an ionic crystal are alternately spaced positive and
negative ions. The force of attraction between the oppositely charged ions constitutes an ionic
bond. Some substances are composed of molecules rather than ions. Molecules are neutral
species composed of atoms which are held together by covalent bonds. Covalent bonds are the
result of an attraction between the positive nuclei of two atoms and the negative electrons
shared by the two atoms. When molecules of gases condense, they form molecular liquids and
molecular crystals. In these crystals the lattice points are occupied by molecules. The
molecules in a molecular crystal are composed of atoms which are held together by covalent
bonds.
Properties such as melting point, boiling point, solubility, electrical conductivity, and color are
some of the properties that can be used to distinguish between the different bond types. This
experiment investIgates some physical properties of two solids – one a typical ionic compound
and the other a typical covalent compound
Materials:
Chemicals:
naphthalene, C10H8 (use ~ 0.1 g sample for each trial)
sodium chloride, NaCl
copper strips or squares
quartz crystals (silicon dioxide)
trichlorotrifluoroethane (TTE) C2Cl3F3 or cyclohexane
water
Equipment:
goggles
Bunsen burner, or candle
matches or lighter
test tubes
test tube holder
test tube rack
disposable squeeze pipets or small graduated cylinders
conductivity testers
52
Procedure:
1. Hardness:
a. Test the hardness of each compound by rubbing a small sample between your
fingers.
b. Record the hardness as soft and waxy, brittle and granular, hard and malleable, or
hard and glassy.
c. Wash your hands after testing.
2. Appearance and volatility:
a. Place a small sample of each of the four compounds in separate test tubes.
b. Observe the appearance of each sample. Note the odor of each. If you detect an
odor, assume that the substance is volatile. If there is no odor, assume that it is
nonvolatile.
c. What deduction can you make about the type of forces between each type of
substance?
3. Melting point:
a. Heat each test tube from step 2 in turn, and record the time it takes for any change
to occur. Do not heat for more than 1 minute, record the qualitative melting time for
any substance that did not melt as >1 minute.
b. How is “melting time” related to the melting point of a substance?
c. Which type of compound(s) seem to have the higher melting point?
4. Solubility in water:
a. Place a sma11 amount of each of the four substances in separate test tubes. The
naphthalene and the sodium chloride should be about equal in mass.
b. Add approximately 5 mL of water to each tube.
c. Shake each test tube vigorously and describe the solubility of each compound in
water.
d. For any soluble substance, save the solution for conductivity testing.
5. Solubility in TTE:
a. Place a sma11 amount of each of the four substances in separate test tubes. The
naphthalene and the sodium chloride should be about equal in mass.
b. Add approximately 2 mL of TTE to each test tube in the fume hood
c. Shake the test tube and describe the solubility of each substance in TIE.
d. For any soluble substance, save the solution for conductivity testing.
e. When finished dispose of the contents of your test tube in the organic waste
container in the fume hood.
6. Conductivity:
a. Using the conductivity tester, observe the conductivity of each compound in the
solid state and in solution.
b. Any substance that was soluble in TTE must be tested in the fume hood.
Data Analysis:
1. Use your knowledge of the periodic table, bond types and electronegativities to classify
the substances as either covalent, ionic, metallic or network covalent.
2. Explain in terms of type and relative strengths of bonds, the presence or absence of
odors of each of the substances.
3. Explain in terms of type and relative strengths of bonds the difference in melting point of
each of the substances.
4. Are you comparing the relative strengths of covalent and ionic bonds when you are
comparing relative melting points of NaCl and C10H8? Explain.
5. Did either of the crystals appear to be soft or waxy? How do you account for any
observed differences in hardness of the crystals?
6. How do you explain the conductivities observed during the procedure?
Conclusion:
In your conclusion summarize the physical properties of a substance as related to bond type.
53
Properties of Chemical Bonds
Ionic
Covalent
Metallic
Network
Covalent
Bond Formation
Elements
Involved
Type of Structure
Physical State
Melting/Boiling
Point
Solubility in
Water
Electrical
Conductivity
Other Properties
Example
54
Teacher Background:
Intramolecular forces involve the bonding between atoms in a molecule or compound. The
bonding involves electrons and the way they are shared or transferred. The properties of
elements can be generally explained in terms of electron occupancy at the highest energy level
in the atom. These electrons are usually called valence electrons. Elements whose atoms have
relatively few valence electrons are typically metals, while those with relatively large numbers of
valence electrons are typically nonmetals. This is particularly true for the representative
elements (main group elements). For example, alkali metal and alkaline earth elements are
typically metals whereas oxygen family elements and halogens are typically nonmetals.
Atoms form molecules and gain stability (lowered potential energy) through covalent bonding by
sharing one or more electron pairs. Electron pair sharing is typical of nonmetals and is best
illustrated for the hydrogen molecule, a case of "equal sharing." Two isolated hydrogen atoms
have only one electron each. As the atoms approach each other, the electron of one atom is
attracted by the nucleus of the other atom, and vice versa. This mutual attraction by two nuclei
for an electron pair gives rise to the covalent bond, with an excess of attraction over repulsion.
Only "like" atoms (e.g., same electronegativity) form such equal-sharing, nonpolar bonds. Most
covalent bonds are not "equal sharing" since there is frequently a difference in electronegativity.
In these cases the bond is called a polar covalent bond. This means that the bond has a
positively charged and negatively-charged end. However, the charges are not nearly as large as
the charges on ions in ionic solids. It is common practice to show the bonding in molecules in
terms of Lewis-dot formulas, named in honor of G.N. Lewis. In these formulas, the elemental
symbols represent the nucleus and all the electrons except valence electrons. These are
represented as dots-one dot means one electron, two dots two electrons, and so on. The
structures are consistent in most simple cases with the octet rule.
Properties of covalent bonds:
•
•
•
•
•
•
Compounds that contain only covalent bonds are called molecular compounds: made of
nonmetals
May be a diatomic molecule: molecule containing only two atoms
o Six naturally occurring in their normal state made of only one type of atom:
o HBrONClIF: hydrogen H2; bromine Br2, oxygen O2; nitrogen N2; chlorine Cl2;
iodine I2; and fluorine F2
Molecular compounds have lower solubility, lower melting points, lower boiling points,
and are very poor conductors of electricity as compared with ionic compounds
They exist as individual molecules rather than as part of a crystal lattice: each formula
unit represents a single entity that is not strongly bonded to other molecules of the same
type
Ionic compounds by contrast do not exist alone as their formula units might seem to
imply: they exist only as large groups in a crystalline arrangement
Molecular compounds have lower melting and boiling points precisely because they
consist of separate molecular units; the atoms are still bound strongly together but the
molecules are not bound to one another
Now consider the opposite extreme. When a metal and nonmetal form a compound, most often
the nonmetal attracts electrons more strongly than the metal (i.e., it has a larger
electronegativity). In such a case the electron pair is "taken over" by the more electronegative
atom to form a negatively charged ion. The metal atom, by virtue of losing an electron, acquires
a positive charge to form a positively charged ion. This is essentially what happens between an
55
alkaline metal and a halogen. If two electrons are "transferred" as between an alkaline earth
element and an oxygen family element, then 2+ and 2- ions are formed. In such cases the
bonding is called ionic bonding and the stability (lowered potential energy) is due to the mutual
attraction between oppositely charged ions in the solid crystals these compounds form.
Properties of ionic bonds:
•
•
•
•
•
•
Most are crystalline solids: brittle, cleavable
Exist in lattice structures: rigid, regular pattern
Many are salts
Strong bonds: high melting and boiling point
Most are soluble in water:
o ionize (dissociate) completely
o become aqueous solution
Conductors of electricity
o do not conduct electricity as a solid
o do conduct electricity when molten or in aqueous solution
The bonding categories considered thus far-covalent and ionic-explain the structure and
properties of many substances. But metals, covalent network solids, and molecular solids are
somewhat unique and require additional attention.
Covalent-network solids are covalently bonded compounds that do not contain individual
molecules, but can be pictured as continuous, three-dimensional networks of bonded atoms.
These are giant molecular lattice structures. This implies that strong covalent bonding holds
their atoms together in a highly regular extended network. The bonding between the atoms goes
on and on in three dimensions. Melting requires the separation of the species comprising the
solid state, and boiling the separation of the species comprising the liquid state. Because of the
large amount of energy needed to break huge numbers of covalent bonds, all giant covalent
network structures have high melting points and boiling points and are insoluble in water.
Diamond, graphite (allotropes of carbon) and quartz (silicon (IV) oxide, SiO2) are examples.
Bonding in metals, called metallic bonding, involves valence electrons. These electrons are
loosely held by any one atom and collectively form a "sea of valence electrons" that can be
used to explain many metallic properties, e.g., metallic luster, malleability, electrical conductivity,
etc. The electrons are loosely held since each atom has several unoccupied valence orbitals; it
is relatively easy for the electrons to move about. In this manner the electrons allow atoms to
slide past each other and be "worked" (hammered) into shapes and drawn into wires (evidence
of malleability and ductility). The mobile electrons in appropriate circumstances move and
conduct electricity and heat.
56
CHEMICAL REACTIONS
•
•
•
•
•
Chemical reactions occur all around us, for example in health care, cooking, cosmetics,
and automobiles. Complex chemical reactions involving carbon-based molecules take
place constantly in every cell in our bodies.
Chemical reactions may release or consume energy. Some reactions such as the
burning of fossil fuels release large amounts of energy by losing heat and by emitting
light. Light can initiate many chemical reactions such as photosynthesis and the
evolution of urban smog.
A large number of important reactions involve the transfer of either electrons
(oxidation/reduction reactions) or hydrogen ions (acid/base reactions) between reacting
ions, molecules, or atoms. In other reactions, chemical bonds are broken by heat or light
to form very reactive radicals with electrons ready to form new bonds. Radical reactions
control many processes such as the presence of ozone and greenhouse gases in the
atmosphere, burning and processing of fossil fuels, the formation of polymers, and
explosions.
Chemical reactions can take place in time periods ranging from the few femtoseconds
(10-15 seconds) required for an atom to move a fraction of a chemical bond distance to
geologic time scales of billions of years. Reaction rates depend on how often the
reacting atoms and molecules encounter one another, on the temperature, and on the
properties--including shape--of the reacting species.
Catalysts, such as metal surfaces, accelerate chemical reactions. Chemical reactions in
living systems are catalyzed by protein molecules called enzymes.
Specific Instructional Strategies:
Time Frame: The lesson can be accomplished in one 70 – 90 minute or two 50-minute time
frames.
Engage: Perform simple experiments with compounds representing the types of chemical
bonds. This can include visual observation of physical characteristics, solubility, melting point,
and conductivity.
1. Class Discussions Collaborative Teamwork: have the students break up into small groups
to discuss observations and answer the following questions taken from the experiment:
a. Use your knowledge of the periodic table, bond types and electronegativities to
classify the substances as covalent, ionic, metallic or network covalent.
b. Explain in terms of type and relative strengths of bonds, the presence or absence of
odors of each of the substances.
c. Explain in terms of type and relative strengths of bonds the difference in melting
point of each of the substances.
d. Are you comparing the relative strengths of covalent and ionic bonds when you are
comparing relative melting points of NaCl and C10H8? Explain.
e. Did either of the crystals appear to be soft or waxy? How do you account for any
observed differences in hardness of the crystals?
f. How do you explain the conductivities observed during the procedure?
2. Students Presentations: The students will report out and explain observations.
57
Management and Safety Issues:
• Demonstration and laboratory activities may involve dangerous chemicals.
• If a hood is not available for student use, the solubility of the compounds in the organic
solvent should be done as a demonstration by the instructor.
• Follow all safety precautions and chemical disposal procedures.
Equity:
Instruction is differentiated according to learner needs to enable all learners to meet or exceed
the expectation of the course objective.
Strategies may include:
• Offer students a variety of presentation modes.
• Provide students with focus activities such as KWL, question of the day, puzzles or
quizzes.
• Provide students with graphic organizers.
• Provide the students the opportunity to work together in small cooperative groups.
o This may include flexible grouping or jigsaw.
• Provide students with mentoring/peer coaching.
• Provide students with computer based learning centers.
• Provide students with additional professional tutoring as needed.
Assessment:
Informal: Through group presentation; bell quiz; classroom participation system.
Formal:
1. Students submit observations of demonstration/experiments and answers to questions.
2. Students complete and turn in chemical bond table.
3. Quiz/test: Students will describe the formation of the different types of chemical bonds.
Students will compare and contrast the physical characteristics of chemical bonds and
predict the type of bonding in compounds given physical characteristics.
Applications:
Chemical bonding plays a key role in experimenting with solvents and adhesives (think post-it
notes!) and is important in the fabric and polymer industry.
58
References:
Gregory, Gayle H. Chapman, Carolyn. Differentiated Instructional Strategies, One Size Doesn’t
Fit all. 2002. Corwin Press, Inc. Thousand Oaks, California.
http://www.chemsoc.org/pdf/LearnNet/rsc/miscon.pdf
http://educ.queensu.ca/~science/main/concept/chem/c07/C07CDTL1.htm
http://intro.chem.okstate.edu/ChemSource/Bond/bonding.html
http://www.savitapall.com/
Ohio Department of Education
Silberberg. Chemistry, The Molecular Nature of Matter and Change. 4th ed., 2006. McGraw
Hill, Boston.
59
Conservation of Matter
Taken from Stop Faking It! Chemistry Basics
You will need a votive candle, a small pan of water, and a glass that is large enough to fit over
the candle. Put about a centimeter’s depth of water in the pan and place the candle in the water.
Light the candle and place the glass upside down in the pan over the candle. As the candle
goes out, what do you notice?
Use pgs. 76-81 and describe what is going on. Use the following vocabulary in your description:
chemical equation, reactant, product, law of conservation of mass, balanced equation, and air
pressure.
60
Back to the beginning – what was going on it those initial chemical reactions we performed?
Instance
1. Adding
vinegar to baking
soda
Explanation using chemical symbols and balanced equations
2. “Pouring” the
contents onto a
candle
3. Burning a
wooden match
4. Lighting a
match under an
inverted cup
5. Burning
Epsom salts
61
Reflection of Activities
5E Lesson
Engage:
Explore:
Explain:
Extend:
Evaluation: Occurred throughout
62
Day Four: Acids and Bases
Acids and Bases at Home
Taken from the Ohio Department of Education, Instructional Management System lesson plans
(https://ims.ode.state.oh.us/ODE/IMS/Search/GSASearchResults.asp)
1. Discuss pre-assessment questions in class. Begin to construct a K-L-H chart (what I know,
what I learned and how I can find out more) during the discussion that can be referenced
and completed throughout the learning cycle.
2. Demonstrate the use of litmus paper and pH paper in the class. Test an acid, base, distilled
water and de-ionized water.
3. Give each person 10 to 12 strips of pH paper to use at home.
4. Have students test 10 different substances at home. All students must test vinegar, baking
soda and eight other household substances of their choosing from the following list:
ketchup, mustard, cooking oil, salad dressing, fruit juices, cola, ashes, hand soap, coffee,
milk, fertilizer, glass cleaner, dill pickles, potatoes, eggs, cottage cheese and soil. A student
may test a substance that is not listed with prior permission from the teacher. For a teacher
reference sheet, see Attachment D, pH of Common Substances.
5. Have students test a solution of the substance. To test a liquid, pour out a small sample into
a clean container and insert the strip. To test a powder, break off a small piece and mix it
with water to form a solution or a diluted mixture and then test it with a strip.
6. Have students record the brand names of the substances that are tested and their pH
levels.
7. Have students record the information in a table with the pH test strip attached alongside the
data. Tell students to cover the strip with clear tape (package tape) to minimize color loss.
Alternatively, the data can be presented in bar graph format.
8. Compile the results in class and compare readings where there is duplication of testing.
Instructional Tip:
Test results of the same brands should have consistent results. If not, try to determine why
(e.g., bad data, improper procedure, carelessness). Be sure to use a pH paper that has a
separate color for each specific pH.
9. Construct a chart and place the results of the testing on the chart to show whether each
tested material is an acid or a base.
Acid______|_________________|__________________|______Base
0
7
14
10. Ask questions that help students evaluate the results of the testing. For example: What
kinds of materials are in the basic range? Acidic range? Ask students to update their K-L-H
charts to include what I know and learned about acids, bases and the pH scale.
11. As a transition to the following demonstration, ask students to compare the acidity of apples
to carrots where the pH difference is 1.
12. Perform a demonstration that illustrates the nonlinearity of the pH scale. Show through a
series of dilutions that a 10-fold change in concentration results in a pH change of one. See
Attachment E, pH of HCl and NaOH Solutions for a table of the concentrations and expected
pH values after each dilution.
63
13. Give students a copy of the blank table. As each dilution is made, fill in the new
concentrations and the measured pH in a table on the board or overhead. Ask students to
fill in their tables at the same time.
Instructional Tip:
Even if students don’t understand the concept of molarity, they can understand that it is a
method chemists use to express the concentration of solutions.
a. Start with 100 mL of 0.1 M HCl in a beaker that is labeled in large letters (0.1M and
10-1M).
b. Measure the pH of the solution using a pH meter and pH paper or universal
indicator.
c. Dilute the solution by pouring 10 mL of the 0.1 M solution into a 100 mL graduated
cylinder and adding 90 mL of distilled water. Pour the new solution into a clean 250
mL beaker, labeled with the new concentration (0.01 M and 10-2 M), and stir.
Measure the pH by the same method used in step one.
d. Continue the dilution process five more times, labeling new solutions with the new
concentrations.
Instructional Tip:
After the first two dilutions, ask students to predict the pH of the new solutions before they are
tested.
e. Repeat the process with 0.1 M NaOH.
14. Ask questions to help students conclude the relationship between concentration and pH.
For example: What happens to the concentration of the acid as water is added to it? What
happens to the pH of the acid as water is added to it? What is the relationship between the
concentration of an acid and the pH? What is the relationship between the concentration of
a base and the pH? Refer to the question about the relative acidity of apples and carrots.
(Since there is a pH difference of one, the acid concentration in an apple is 10 times greater
than in a carrot.)
15. Discuss with the students the use of diluted and concentrated solutions in real-life
applications. Some common examples may include: the dilution of one cup of concentrated
car wash solution in one gallon of water; the dilution of concentrated floor cleaner in water;
mixing fertilizer for gardens; or the use of various pH ranges in soaps and shampoos.
16. Have students update their K-L-H charts for the final time.
64
Homework / Discussion Questions
1. What is pH? Describe the pH scale.
2. What is a hydronium ion?
3. How can the pH of a solution be determined?
4. What are the properties of acids?
5. What are the properties of bases?
6. What compounds are formed when an acid reacts with a base?
7. Describe properties of acids and bases that can cause harm or injury to self, others
and/or the environment.
8. Which solution is more acidic, one with a pH of 2 or another with a pH of 6?
65
The Chemistry of Hair
Taken from http://www.sciencenetlinks.com/lessons.cfm?BenchmarkID=8&DocID=18
Purpose
Students will do hands-on activities and read information online in order to answer the central
question of this lesson: How does understanding the chemistry of hair care, including the role of
pH, help in the development of better hair-care products?
Context
It is important for high-school students to begin to appreciate the importance of scientific
research. Increased scientific knowledge is what continues to spur technology; at the same
time, as the base of scientific knowledge increases, technology advances. In this lesson,
students will investIgate how scientific research helps to develop the most effective types of
hair-care products.
The ultimate goal of this lesson is for students to answer the central question: How does
understanding the chemistry of hair care, including the role of pH, help in the development of
better hair-care products? In order to do this, students will do hands-on activities with shampoo
and hair samples, as well as read an online article about the pH of hair care products.
This lesson is most appropriate for an introductory chemistry course. Prior to this lesson,
students should have been introduced to acids, bases, and the pH scale. This lesson
complements previous instruction on acids and bases by providing a real-world context in which
students investIgate the impact of scientific research on hair-care products.
Planning Ahead
Materials:
 Effect of pH on Hair Resilience student sheet
 Effect of pH on Hair Resilience: Answer Key
 Shampoo samples—each student should bring one sample from home
 Supplies to test pH (e.g., pH strips or probes)
 Hair samples (Each group will need 20 strands of the same hair; strand length should be
approximately 6 inches. You could obtain these from a hairdresser, or students could
use their own hair.)
 Wooden splints
 Petri dishes
 Tape
 Paper towels
 Standard pH solutions (neutral; pH 2.0; pH 6.0; pH 10.0; pH 12.0)
 Microscopes
 Safety goggles
66
Motivation
First, ask the following questions to focus students on the topics of hair and hair care:





Have you ever wondered why your hair looks good one day and terrible the next?
Is there anything that you try to do to fix your hair on a "bad hair day?"
What are some of the products you use on your hair on a regular basis?
How do these products impact the condition of your hair?
Have you ever done something to your hair that really changed it?
Then help students focus on the science of hair care by asking this question:

What do you think acids and bases might have to do with hair care products?
Briefly review acids, bases, and pH and continue talking about these in terms of hair care. Ask
the following questions:






What is pH?
What are acids?
What are bases?
What are some methods to test pH?
What role do you think pH plays in terms of hair care?
Do you think it's more likely that an acidic, basic, or neutral product is best for your hair?
Finally, write the central question for this lesson somewhere where all students can see it: How
does understanding the chemistry of hair care, including the role of pH, help in the development
of better hair-care products? Let students know that the rest of this lesson will involve
experimenting and reading information online to answer this question.
Development
The Development is divided into three sections, all outlined for the students on the student
sheet. Distribute the Effect of pH on Hair Resilience
(http://www.sciencenetlinks.com/pdfs/hair_actsheet.pdf) student sheet at this time.
67
Part I: Determining the pH of Shampoo Samples
This part relies on shampoo samples that the students brought in from home. List the names of
the shampoos and have students vote to decide the favorite brands of the class.
Break students into lab groups. Give each lab group a set of shampoo samples for which they
will determine pH; distribute the samples so they all get tested. Students will record the pH of
their samples on their student sheets.
Note: Have students determine pH by using a method familiar to them. For example, using pH
strips or probes. Also, it would be a good idea to have students wear safety goggles during this
activity.
After the pH of all samples has been recorded, ask the following questions:


Were most shampoos acidic or basic? (Most should've been acidic.)
What about the shampoos you voted as your favorites? Were they acidic or basic?
Based on this activity, ask students to come up with an initial answer to the central question of
the lesson: How does understanding the chemistry of hair care, including the role of pH, help in
the development of better hair-care products?
Part II: Treating Hair Samples in Solutions of Varying pH
This part of the lesson involves testing hair samples in solutions of different pH. Distribute a hair
sample to each group (20 strands of the same type of hair; they will eventually divide the
sample into 4 groups of 5 strands each) and have students complete the activity by following the
procedure on the student sheet.
Note: The test is subtle but shows expected results if done correctly. Observations of hair in
each pH sample should include:




pH 2.0: hard; smooth; not resilient; breaks easily
pH 6.0: not as hard; smooth; very resilient; resists breaking
pH 10.0: rough; not very resilient; tends to break easily
pH 12.0: very rough; not resilient; tends to break very easily
When all students are finished with the activity, discuss the questions they answered on their
student sheets (refer to Effect of pH on Hair Resilience: Answer Key
(http://www.sciencenetlinks.com/pdfs/hair_teachsheet.pdf) for the questions from the student
worksheet with suggested responses).
68
Part III: Online Exploration of Hair Care
In this section of the lesson, students will go to the Exploratorium's website, Better Hair Through
Chemistry (http://www.exploratorium.edu/exploring/hair/). Here they will read the introduction,
page two, and page three and answer questions on their student sheets. When they're finished,
discuss the questions in class (refer to Effect of pH on Hair Resilience: Answer Key for the
questions from the student worksheet with suggested responses).
Assessment
Ask students the following questions:


What is your final answer to the central question: How does understanding the chemistry
of hair care, including the role of pH, help in the development of better hair-care
products? (Students should understand that a pH that is too high or too low can
adversely affect hair resilience. They should be able to explain that researchers continue
to test substances to attempt to determine desirable characteristics, including desirable
pH.)
Describe how scientific research plays a role in the development of hair-care products
over time. (Students should understand that research provides new information that
leads to the development of better hair-care products over time. They should understand
that this research is ongoing, partly accounting for the new hair-care products they see
advertised.)
Students could create an advertisement for a shampoo. This could be a shampoo that's
currently on the market, or one that they create. The focus of the advertisement should be on
the science of the shampoo: What about the chemistry of the shampoo makes it good?
Students should include the following in their advertisements:



Name of the shampoo
Information about the chemistry of the shampoo (e.g., pH), and how this impacts the
quality of the shampoo
Sufficient background information about the chemistry (e.g., pH), so that general
audiences can understand the advertisement
Extensions
Students can read articles about the science of hair care, including How Hair Coloring Works
(http://www.howstuffworks.com/hair-coloring1.htm), at How Stuff Works.
Students can further explore the impacts of shampoos, dyes, and permanents at the American
Chemical Society website: Hair and the Products We Use (Part 1 http://www.chemistry.org/portal/a/c/s/1/feature_ent.html?id=cc8f8c92cca911d5ea024fd8fe80010
0 and Part 2 http://www.chemistry.org/portal/a/c/s/1/feature_ent.html?id=6748ced4cca911d5ea024fd8fe8001
00).
69
Effect of pH on Hair Resilience
Student Sheet
There are three components to this lesson, outlined below. Complete the activities in order to
answer the central question of this lesson: “How does understanding the chemistry of hair care,
including the role of pH, help in the development of better hair care products?”
Part I: Determining the pH of shampoo samples
Using the shampoo samples given to you by your teacher, determine the pH of each of the
samples. You can determine pH by using a method familiar to you, such as using pH strips or
probes. Record the pH of your shampoo samples below:
Shampoo
pH
70
Part II: Treating hair samples in solutions of varying pH
Complete the following activity in your lab group and answer the questions that follow.
Procedure:
1. Obtain 4 wooden splints; 4 test dishes; 20 strands of the same type of hair; and 4 strips of
tape.
2. Clean the 4 dishes in pH neutral solution and rinse thoroughly with distilled water. (Be sure to
clean all glassware after each use so that the samples are not contaminated.)
3. Label the test dishes pH 2.0, pH 6.0, pH 10.0, and pH 12.0. Add 10 mL of the appropriate pH
solution to each of the dishes.
4. Tape 5 strands of hair to each splint with one end fastened, and the other end free to be
immersed in the test solutions. Label the ends of each splint with pH 2.0, pH 6.0, pH 10.0, and
pH 12.0.
5. Put each splint into the corresponding solution. Allow the hair to be exposed for 10 minutes.
6. Remove the hair sample and rinse with distilled water. Allow the strands to air dry.
7. Grasp the ends of the pH 2.0 sample and pull gently. Record observations of the following in
the data table: texture (e.g., rough, smooth) and resilience (hairs’ ability to stretch and contract
without breaking).
8. Observe the hair under the microscope. Sketch what you see and record notable
observations in the table (e.g., texture, smoothness).
9. Repeat for other samples.
pH Treatments
pH 2.0
Texture
Resilience
Sketch of Hair
pH 6.0
pH 10.0
pH 12.0
71
Analysis questions:
1. The hair sample treated in what pH was the most resilient after treatment?
2. The hair sample treated in what pH was the least resilient after treatment?
3. Based on test results, what seems to be the best pH range for hair?
4. Describe further research that would better determine the optimal pH range for hair care
products.
5. How would you answer the central question of the lesson now: “How does understanding the
chemistry of hair care, including the role of pH, help in the development of better hair care
products?”
72
Part III: Online exploration of hair care
Go to the Exploratorium’s website, Better Hair Through Chemistry
(http://www.exploratorium.edu/exploring/hair/). Read the introduction, page two, and page three
and answer the following questions:
1. What are some factors that impact the condition of hair?
2. What could be causing your hair to be limp?
3. What are the differences between hair follicles and hair shafts?
4. When you cut yourself, can your skin heal? If so, why?
5. If you damage your hair (e.g., by using the wrong types of hair care products) can it heal?
6. What is the outermost layer of the hair shaft called?
7. What is the role of the cuticle?
8. What happens to cuticles in acidic solutions?
73
9. What happens to cuticles in basic solutions?
10. What happened to the author’s hair when she put it in an acidic solution? In a basic
solution?
11. Does that match what happened to your hair in this lesson’s activity?
12. According to the article, how does shampoo work?
13. Which is better for your hair, detergent or soap? Why?
14. What does rinsing in acidic solution (e.g., vinegar) do for your hair?
15. Does this article support the results of your in-class activities? Why or why not?
74
The Acid Stomach
Taken from http://www.sciencenetlinks.com/lessons.cfm?BenchmarkID=8&DocID=380
Purpose
To develop an understanding of how aspirin works and how understanding it's interaction with
other chemicals in the body aided doctors in medical research.
Context
This lesson is intended for a high-school, introductory chemistry class or health class. To
complete the lesson, students must understand acids and bases. The lesson does provide for
instruction in acids and bases if it is necessary. The lesson begins with an article on the history
of the development of aspirin. Students will then complete a lab that compares the reaction of
regular aspirin, buffered aspirin, and enteric aspirin in neutral, acidic, and basic solutions. They
will then analyze the results of the experiment to gain insight into how this information was used
by researchers to solve some of the problems associated with aspirin.
Planning Ahead
Materials:
 Acid Stomach student E-Sheet
Note: In the Going Online and Understanding What You Learned sections of the E-Sheet,
students will answer questions using an online tool. As an alternative, students can answer
the same questions on the printable Aspirin Article
(http://www.sciencenetlinks.com/pdfs/acid1_actsheet.pdf) and Understanding What You
Learned student sheets (http://www.sciencenetlinks.com/pdfs/acid3_actsheet.pdf)
Simulated Stomach Lab Data Sheet (http://www.sciencenetlinks.com/pdfs/acid2_actsheet.pdf)
 Safety goggles
 9 plastic cups
 Aspirin, Buffered Aspirin, Enteric Aspirin
 600 mL water
 300 mL vinegar
 45 g baking soda
 Stop watch or a clock with a second hand
Motivation
Using the Acid Stomach student E-Sheet
(http://www.chemistry.org/portal/a/c/s/1/acsdisplay.html?DOC=vc2%5C1rp%5Crp1_aspirin.html
) , students should read Product report on aspirin from the American Chemical Society site.
Discuss students' answers to these questions found on the E-Sheet:
 What do willow tree bark extract, oil of wintergreen, and aspirin have in common? (What
these compounds have in common is their anti-inflammatory properties and they are some
of the oldest and most frequently used drugs.)
 The study of the chemistry of medicinal plants began in the 1800s. Why would it have been
difficult to identify the active ingredients in those plants? (Chemical techniques of the day
were relatively simple. In the bark of the willow tree, there would be hundreds of different
compounds. Separating them from one another and identifying their effects in the body
would have been very difficult with the limited knowledge and techniques.)
 What were some of the drawbacks to salicylic acid as a pain reliever? (Salicylic acid is very
irritating to the stomach. It can cause severe heartburn.)
75





Felix Hoffman, who worked for the Bayer Company, invented aspirin in 1899. How did he
make it? (By reacting acetic acid with salicylic acid to produce acetylsalicylic acid.)
What are some of the benefits of aspirin? (It relieves fever, pain, and inflammation, prevents
some types of heart attacks, and inhibits clotting.)
How does aspirin work? (Aspirin stops the production of hormone-like compounds called
prostaglandins. Aspirin interferes with the action on cyclooxygenase, which is the enzyme at
the beginning of prostaglandin synthesis.)
What are some strategies for reducing stomach irritation caused by aspirin? (Buffered
aspirin is a combination of aspirin with some other compounds to reduce acidity. Enteric
aspirin is coated with a substance that allows the pill to pass through the stomach without
being dissolved, thereby eliminating stomach irritation.)
What are some other medical discoveries that have been found as a result of our
understanding of how aspirin works? (A specific prostaglandin that promotes coagulation of
blood and another that inhibits it have been identified. A new group of prostaglandins that
are related to the inflammation of asthma has also been discovered.)
Be sure that students save their answers to these questions because they will revisit them in the
Assessment.
Development
Review acids/bases with your students. Depending on the level of the students, you could have
them read: About Acids
(http://www.chemheritage.org/EducationalServices/pharm/tg/asp/acid.htm) as a review of
acids/bases. This site is also very useful as a review for you if one is needed. You should use
your discretion as how to best utilize this site.
After students have reviewed acids and bases, introduce the lab portion of the lesson by saying,
"We will do an activity to better understand how buffered aspirins work."
Then refer students back to the E-Sheet, which will direct them to Simulated Stomach
(http://www.chemistry.org/portal/a/c/s/1/acsdisplay.html?DOC=vc2%5C12do%5Cdo12_aspirin.h
tml). Before they begin the lab, pass out the Simulated Stomach Lab Data Sheet
(http://www.sciencenetlinks.com/pdfs/acid2_actsheet.pdf) and instruct them to record their
observations in the data tables found there.
In doing this lab, students should find that when the three types of aspirin are dropped in water,
the buffered aspirin may quickly begin to bubble and disintegrate. The enteric aspirin will
eventually begin to disintegrate in the water, but it takes a very long time for the coating to
dissolve and will not likely happen during a class period. In the acidic solution, the buffered
aspirin very quickly begins to bubble vigorously. The regular aspirin disintegrates in the acidic
solution just the way it does in water. The enteric aspirin can soak in the acidic solution for
several hours without dissolving. In the basic solution (baking soda), all three types of aspirin
will dissolve relatively quickly, although the enteric aspirin still takes longer than the other two.
(In these solutions, vigorous bubbling—probably more than seen in any case previously—
should be seen in all cases as the acidic proton on aspirin reacts with the bicarbonate ion to
produce carbonic acid, which breaks down to carbon dioxide gas and water.)
Assessment
Have students answer these questions either online or on the printable student sheet,
Understanding What You Learned (http://www.sciencenetlinks.com/pdfs/acid3_actsheet.pdf).
The first four questions are repeats of some of the questions found in the Motivation.
76








What were some of the drawbacks to salicylic acid as a pain reliever? (Salicylic acid is very
irritating to the stomach. It can cause severe heartburn.)
What are some of the benefits of aspirin? (It relieves fever, pain, and inflammation, prevents
some types of heart attacks, and inhibits clotting.)
How does aspirin work? (Aspirin stops the production of hormone-like compounds called
prostaglandins. Aspirin interferes with the action of cyclooxygenase, which is the enzyme at
the beginning of prostaglandin synthesis.)
What are some strategies for reducing stomach irritation caused by aspirin? (Buffered
aspirin is a combination of aspirin with some other compounds to reduce acidity. Enteric
aspirin is coated with a substance that allows the pill to pass through the stomach without
being dissolved, thereby eliminating stomach irritation.)
How would knowledge of the way aspirin reacts in acidic, basic, and neutral (water)
solutions help in solving the problem of stomach irritation? (The stomach is an acidic
environment. Knowing how aspirin reacts in an acid helped doctors find ways to reduce the
acidity [Buffered Aspirin]. It also helped them to devise a way for the aspirin to not react at
all in the stomach [Enteric Aspirin].)
How has the understanding of aspirin's molecular structure and its interaction with other
chemicals in the body aided doctors in medical research? (Investigation of aspirin
interactions led to a better understanding of the varied roles of prostaglandins.
Prostaglandins are the cause of some types of inflammation.)
What differences, if any, did you observe in the tablets while in water? In vinegar? In baking
soda solution? (See description of lab above.)
Enteric aspirin is designed to remain intact until it reaches the small intestine. What could
you hypothesize about the pH of the small intestine? (Because enteric aspirin does not react
in the acid, but very quickly dissolves in the basic solution, we might hypothesize that the pH
in the small intestine is basic.)
Extensions
These sites can be used to extend the ideas and concepts in this lesson:
Aspirin Adventures:
http://www.chemheritage.org/EducationalServices/pharm/tg/asp/stuff/welcom.htm
77
Aspirin Article
Copied from:
http://www.chemistry.org/portal/a/c/s/1/acsdisplay.html?DOC=vc2%5C1rp%5Crp1_aspirin.html
Aspirin
By Gail Marsella
Scene One: The year is 1614; the place is now eastern Massachusetts. Four members of the
Wampanoag tribe have developed high fevers. The shaman ventures out into the forest, where
he carefully collects some leaves, roots, and bark from a willow tree. He returns home, grinds
up the plant material, and brews it in water. The patients drink the hot herbal tea, and bathe in a
cooled solution of the ground bark. Within hours, the fevers are lower, and the sick people are
resting comfortably.
Scene Two: The year is 1846; the place is London, England. On the day of the Prince's annual
ball, the Grand Duchess is suffering from severe arthritic joint pain. She sends for her doctor,
and is given oil of wintergreen to swallow. In a short time the inflammation in her joints lessens,
and she can move without pain. The duchess attends the ball, and fulfills her social obligations.
Scene Three: The year is 1999. A high school student, diligently studying for an exam, develops
a headache after several hours of intense concentration. She goes to the medicine cabinet,
takes out a bottle marked "aspirin", and swallows two pills with a glass of water. In less than an
hour, her headache is gone.
Taking medicine to relieve pain, fever, and inflammation is a ritual that has been repeated
through most of recorded history. Willow tree bark extract, oil of wintergreen, and aspirin are
similar in molecular structure and metabolic effect. All three belong to a group of chemicals
called salicylates, and are some of the oldest and most frequently used drugs. Willow trees
contain salicin, oil of wintergreen is methyl salicylate, and aspirin is acetylsalicylic acid (see
Figure).
78
Salicylates have been used as painkillers since ancient times.
Salicin can be extracted from the bark of willow trees, and methyl
salicylate is found in wintergreen plants or teaberry. Aspirin was
first prepared by the acetylation of salicylic acid.
Painful Discoveries
Many cultures have a history of herbal medicine. Studying the chemistry of medicinal plants,
however, began in the 1800s. Imagine the difficulties the early chemists faced! Identifying the
active ingredient in a mound of willow tree bark was a formidable task. From the hundreds of
chemicals contained in the bark, it was nearly impossible to purify the single chemical capable
of relieving pain and fever.
In 1859 German chemist Hermann Kolbe synthesized salicylic acid in his laboratory by heating
phenol with carbon dioxide. Unfortunately, salicylic acid is irritating to the stomach�so much so
that many patients preferred their aches and fever to the severe heartburn caused by the
remedy. So the search was on for a chemical that was similar to salicylic acid�but without the
side effects.
79
In 1899, another German named Felix Hoffman suggested acetylsalicylic acid as a good
alternative to salicylic acid. He had been searching for a drug that would give his elderly father
relief from arthritis, and he stumbled upon acetylsalicylic acid after trying phenyl salicylate and
sodium salicylate without success. The new drug was named aspirin. Hoffman was an
employee of the Bayer Company, which marketed the new remedy with great success. Today,
Americans swallow nearly 50 million tablets a day.
Aspirin can be made by reacting acetic acid with salicylic acid to produce acetylsalicylic acid,
the same procedure used by Dr. Hoffman nearly a century ago. When acetylsalicylic acid ages,
it may decompose and return to salicylic acid and acetic acid. If you have an old bottle of aspirin
around the house, open it and take a sniff. It may smell like vinegar, because vinegar is dilute
acetic acid.
Something for Everyone
Researchers have been puzzled by the many and varied actions of aspirin. This one drug not
only relieves fever, pain, and inflammation, but also inhibits blood clotting. It helps prevent some
types of heart attacks if taken regularly. None of these effects seems to be very closely related.
Despite its many years of use, aspirin's mode of action is only partly understood.
Unlike many painkillers that act directly on the nervous system, aspirin seems to relieve pain
primarily by stopping the production of hormone-like chemical messengers called
prostaglandins. They are produced in small quantities by the same tissue as the one they act
upon, and degrade within a few minutes. During their short lifetime they exert a powerful
influence on the body. Prostaglandins regulate digestion, kidney output, reproduction, blood
circulation, and some nervous system functions.
Aspirin interferes with the action of one particular enzyme, cyclooxygenase, which acts at the
beginning of a chain of prostaglandin synthesis. As a result, all the prostaglandins produced by
this chain of reactions are suppressed. Aspirin's numerous effects reducing fever, enlarging
blood vessels, reducing clotting of the blood come from altering the balance of prostaglandins,
even though aspirin itself disturbs only a single reaction.
Stomach Upset
"Over-the-counter" drugs do not require a doctor's prescription but that doesn't mean they're not
potent medicines. Aspirin is an effective painkiller and fever reducer, but it causes side effects in
some people. The most common complaint is an upset stomach. One strategy for reducing
stomach irritation is to combine the aspirin with a buffer a combination of chemicals that reduces
acidity. The resulting product, "buffered aspirin", is a genuine improvement for the small
percentage of people who are susceptible to this kind of stomach irritation, but it has no value to
the rest of us.
For patients who are under a doctor's orders to take aspirin around the clock every day,
stomach irritation can become a serious issue. Drug companies introduced specially coated
aspirin tablets that pass through the stomach without dissolving. This coating resists gastric
acid, but dissolves quickly in the basic environment of the small intestine. Called "enteric"
aspirin, these tablets effectively eliminate stomach irritation. However, they cannot work until the
stomach contents are passed to the intestine several hours after the tablet is ingested.
80
The discovery that aspirin works by inhibiting prostaglandin opened new avenues of medical
research. A specific prostaglandin that promotes coagulation of the blood and another that
inhibits coagulation have been identified. Following the clue that aspirin reduces most forms of
inflammation but not the inflammation of asthma unearthed a new group of prostaglandins.
Researchers have learned a lot from the once-mysterious ingredient of the bark of the willow
tree.
Reference
Roueche, B. The Medical Detectives; Plume: New York, 1991.
81
All rights reserved. Science NetLinks Student Sheets may be reproduced for educational purposes.
Aspirin Article Student Sheet
1. What do willow tree bark extract, oil of wintergreen, and aspirin have in common?
2. The study of the chemistry of medicinal plants began in the 1800s. Why would it have been
difficult to identify the active ingredients in those plants?
3. What were some of the drawbacks to salicylic acid as a pain reliever?
4. Felix Hoffman, who worked for the Bayer Company, invented aspirin in 1899. How did he
make it?
5. What are some of the benefits of aspirin?
6. How does aspirin work?
7. What are some strategies for reducing stomach irritation caused by aspirin?
8. What are some other medical discoveries that have been found as a result of our
understanding of how aspirin works?
82
Simulated Stomach
Copied from:
http://www.chemistry.org/portal/a/c/s/1/acsdisplay.html?DOC=vc2%5C12do%5Cdo12_aspirin.ht
ml
By David Robson
OBJECTIVE
You can see the difference between regular, buffered, and enteric (coated) aspirin by testing the
tablets in neutral, acidic, and basic solutions. Your stomach is acidic, but your small intestine is
basic. These chemical opposites are separated by the pyloric valve, which opens only briefly to
transfer partially digested food from the stomach to the intestine.
MATERIALS
•
•
•
•
•
•
safety goggles
9 plastic cups
600 mL water
300 mL vinegar
45 g baking soda
stop watch
PROCEDURE
1. Add 100 mL of water to each of three labeled plastic cups.
2. Record the time. Simultaneously add a regular aspirin tablet to one cup, a buffered
aspirin tablet to the second, and an enteric aspirin tablet to the third.
3. Record any changes in the tablets at 30-s intervals until no further change is evident.
4. Repeat steps 1-3 using vinegar in each cup instead of water.
5. Repeat steps 1-3 again, using 15 g of baking soda in 300 mL of water in each cup.
FOLLOW-UP
1. Why did you run the activity in water? In vinegar? In baking soda solution?
2. What differences, if any, did you observe in the tablets while in water? In vinegar? In
baking soda solution?
83
All rights reserved. Science NetLinks Student Sheets may be reproduced for educational
purposes.
Simulated Stomach Lab Data Sheet
Use this sheet to record your observations from the Simulated Stomach lab.
http://www.chemistry.org/portal/a/c/s/1/acsdisplay.html?DOC=vc2%5C12do%5Cdo12_aspirin.ht
ml
Aspirin in Water
Time
Regular
30 sec
Buffered
Enteric
Buffered
Enteric
60 sec
1 min,
30 sec
2 min
2 min,
30 sec
3 min
3 min,
30 sec
4 min
Aspirin in Vinegar
Time
Regular
30 sec
60 sec
1 min,
30 sec
2 min
2 min,
30 sec
3 min
3 min,
30 sec
4 min
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Aspirin in Baking Soda Solution
Time
Regular
30 sec
Buffered
Enteric
60 sec
1 min,
30 sec
2 min
2 min,
30 sec
3 min
3 min,
30 sec
4 min
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Understanding What You Learned
1. What were some of the drawbacks to salicylic acid as a pain reliever?
2. What are some of the benefits of aspirin?
3. How does aspirin work?
4. What are some strategies for reducing stomach irritation caused by aspirin?
5. How would knowledge of the way aspirin reacts in acidic, basic, and neutral solutions help in
solving the problem of stomach irritation?
6. How has the understanding of aspirin’s molecular structure and its interaction with other
chemicals in the body aided doctors in medical research?
7. What differences, if any, did you observe in the tablets while in water? In vinegar? In baking
soda solution?
8. Enteric aspirin is designed to remain intact until it reaches the small intestine. What could you
hypothesize about the pH of the small intestine?
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Wrap Up/Review of the Week
Look back to the academic content standards we list on pages 4-5. Assign each team various
indicators and link the indicators to the activities of the week along with strengths and
weaknesses of the lesson.
Indicator
Activities
Strengths
Weaknesses
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