Table of Contents
Key Principles
The Structure of the Course
Annotated Table of Contents
Key Principles
Even a casual perusal of the IPS textbook reveals how different
it is from other textbooks. As a teacher new to the course you may
wonder about the source of the many differences. Most of the characteristic
qualities of IPS are the result of the consistent application
of the following guidelines:
- Have a clear set of objectives. The broad objectives
of IPS can be summarized as the development of laboratory
skills, reasoning skills (e.g. the application of knowledge to
new situations), and communication skills in the context of science
while gaining an understanding of the foundations of physical
science. This guideline had a profound effect on the construction
of the sequence, as will be explained below.
- Start where the students are. At the eighth or ninth
grade level, all students have had some experience with matter
in their daily life. But many of them associate science with a
specialized vocabulary that must be memorized and that is unrelated
to daily life. Therefore, IPS does not have a set of prerequisites
as far as previous science content is concerned. It bases all
new ideas on concrete student experiences in the laboratory, and
it consistently introduces new terms only after the need for them
has been established.
- Give the students the time they need to digest the material.
The application of this guideline negates the a priori
establishment of required coverage. From the development of the
preliminary edition to the latest changes in this edition we allotted
the time for a given topic on the basis of field-testing; a topic
was eliminated if we thought that the time could be utilized more
productively. A corollary to these considerations is the conclusion
that students are better served by studying even a part of the
course thoroughly rather than rushing through all of it.
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The Structure of the Course
IPS has always had a central theme that was not confined
within the boundaries of individual disciplines, primarily chemistry
and physics. As stated in the preface to the text, the central theme
is the study of matter leading to the development of the atomic
model. In broad terms the course divides naturally into three parts.
- Chapters 1-6 provide the empirical framework without which the
atomic model becomes an answer in search of a question. The progression
is from what is around us in the greatest abundance, namely mixtures,
to compounds and elements. In the process, students learn about
the characteristic properties by which substances are recognized
and separated. No distinction is made between physical and chemical
properties.
- Chapters 7-9 introduce the atomic model. Radioactivity was chosen
as the vehicle because the discreteness in radioactive processes
is clearly observable, and because the subject, despite its importance,
is widely neglected. Radioactivity is one of the topics to which
more time was allotted in this edition.
- Chapters 10-12 add the electric dimension to the atomic model,
reinforcing the material learned earlier. In the process, a valuable
foundation is laid for electrochemistry.
The division of the course along these lines provides natural breaking
points for teachers who wish to spread the IPS course over more
than one year.
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Annotated Table of Contents
The Table of Contents annotated with general comments from the
Teachers Guide and Resource Book provides a more detailed picture
of the course. Sections printed in italics are new to the Sixth
Edition. In the comments "you" refers to the teacher.
Click below to go to the desired chapter.
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CHAPTER 1
VOLUME AND MASS |
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1.1 Experiment: Heating Baking Soda
1.2 Volume
1.3 Reading Scales
1.4 Experiment: Measuring Volume by Displacement of Water
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1.5 Shortcomings of Volume as a Measure
of Matter
1.6 Mass
1.7 Experiment:The Equal-Arm Balance
1.8 Experiment: Calibrating the Balance
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1.9 Unequal-Arm Balances
1.10 Electronic Balances
1.11 Experiment: The Sensitivity of a Balance
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Although this chapter is among the shorter ones in the text, it
is of prime importance. Interwoven are two objectives: the development
of the skills related to the balance and the analysis of data, and
the accumulation of evidence leading to a fundamental law of nature,
the law of conservation of mass. It will take the entire chapter
to reach the objectives.
Histograms, which are introduced in this chapter, will be used
throughout the course. The time you invest in teaching how to construct
them will pay handsome dividends later on. Once the students know
how to construct histograms by hand, we recommend that they use
the software to save time and explore various choices available
to them.
Emphasize to students that a single experiment, involving only
one kind of change (such as dissolving salt), is not in itself very
convincing evidence for concluding that mass does not change when
other changes take place. This is why four separate mass-conservation
experiments, all involving different kinds of change, are included
in this chapter. Do not skip any of them; let your students do all
of them to convince themselves of the plausibility of conservation
of mass.
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CHAPTER 2
MASS CHANGES IN CLOSED SYSTEMS |
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2.1 Experiment: The Mass of Dissolved Salt
2.2 Histograms
2.3 Using a Computer to Draw Histograms
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2.4 Experiment: The Mass of Ice and Water
2.5 Experiment: The Mass of Copper and Sulfur
2.6 Experiment: The Mass of a Gas
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2.7 The Conservation of Mass
2.8 Laws of Nature
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Although this chapter is among the shorter ones in the text, it
is of prime importance. Interwoven are two objectives: the development
of the skills related to the balance and the analysis of data, and
the accumulation of evidence leading to a fundamental law of nature,
the law of conservation of mass. It will take the entire chapter
to reach the objectives.
Histograms, which are introduced in this chapter, will be used
throughout the course. The time you invest in teaching how to construct
them will pay handsome dividends later on. Once the students know
how to construct histograms by hand, we recommend that they use
the software to save time and explore various choices available
to them.
Emphasize to students that a single experiment, involving only
one kind of change (such as dissolving salt), is not in itself very
convincing evidence for concluding that mass does not change when
other changes take place. This is why four separate mass-conservation
experiments, all involving different kinds of change, are included
in this chapter. Do not skip any of them; let your students do all
of them to convince themselves of the plausibility of conservation
of mass.
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CHAPTER 3
CHARACTERISTIC PROPERTIES |
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3.1 Properties of Substances and Properties of Objects
3.2 Experiment: Freezing and Melting
3.3 Graphing
3.4 Experiment: Boiling Point
3.5 Experiment: Mass and Volume
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3.6 Density
3.7 Dividing and Multiplying Measured Numbers
3.8 Experiment: The Density of Solids
3.9 Experiment: The Density of Liquids
3.10 The Hydrometer
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3.11 Experiment: The Density of a Gas
3.12 The Range of Densities
3.13 Identifying Substances
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In the daily language one hears statements like "lead is heavier
than iron." Of course, lead is neither heavier no lighter than
iron, just as lead is neither bigger nor smaller than iron. Mass,
volume, and shape are properties of objects. Properties that do
not depend on the amount of a substance are called characteristic
properties.
The characteristic properties discussed in this chapter and in
Chapter 4 have been selected for their usefulness in identifying
substances and separating mixtures. Hence, we concentrate on freezing
point, boiling point, and density in this chapter, and on solubility
in Chapter 4.
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CHAPTER 4
SOLUBILITY |
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4.1 Experiment: Dissolving a Solid in Water
4.2 Concentration
4.3 Experiment: Comparing the Concentrations of Saturated
Solutions
4.4 Experiment: The Effect of Temperature on Solubility
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4.5 Wood Alcohol and Grain Alcohol
4.6 Experiment: Rubbing Alcohol as
a Solvent
4.7 Sulfuric Acid
4.8 Experiment: Two Gases
4.9 Hydrogen
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4.10 Carbon Dioxide
4.11 Experiment: The
Solubility of Carbon Dioxide
4.12 The Solubility of Gases
4.13 Acid Rain
4.14 Drinking Water
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Solubility is a characteristic property of both the solute and the
solvent. It is expressed in a complex unit-grams of solute per 100
cm3 of solvent. If we know the solubility of
a substance in a given solvent and the quantity we want to dissolve,
we can calculate the minimum amount of solvent necessary. Or, if
we know how much solvent we have, we can use the solubility to find
the maximum amount of the solute we can dissolve in it.
Like density, solubility changes with temperature. However, the
solubility of some substances changes rather dramatically with temperature,
whereas the density of solids or liquids changes only slightly.
The dependence of solubility on temperature is very useful in separating
substances in solution.
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CHAPTER 5
THE SEPARATION OF MIXTURES |
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5.1 Experiment: Fractional Distillation
5.2 Petroleum
5.3 The Separation of Insoluble Solids
5.4 Experiment: The Separation of a Mixture of Solids
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5.5 The Separation of
a Mixture of Soluble Solids
5.6 Experiment: Paper Chromatography
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5.7 A Mixture of Gases: Nitrogen and Oxygen
5.8 Low Temperatures
5.9 Mixtures and Pure Substances
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As we mentioned earlier, one of the criteria for selecting characteristic
properties for discussion was their usefulness in separating substances.
Now we will employ these properties for actual separations in the
laboratory, describe some applications of these methods in industry,
and arrive at an operational definition of a pure substance. Reading
through this chapter, you may get the impression that we are leaving
students with a rather vague definition of a pure substance. This
is true. The boundary between a mixture and a pure substance is
not so sharp as may be believed from reading some textbooks. If
your students realize at the end of this chapter that a pure substance
is something that cannot be broken up by any of the methods discussed,
they will have learned their lesson.
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CHAPTER 6
COMPOUNDS AND ELEMENTS |
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6.1 Experiment: The Decomposition of Sodium Chlorate
6.2 Experiment: The Decomposition of Water
6.3 The Synthesis of Water
6.4 Experiment: The
Synthesis of Zinc Chloride
6.5 The Law of Constant Proportions
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6.6 Experiment: A Reaction with Copper
6.7 Experiment: The Separation of a Mixture of Copper Oxide
and Copper
6.8 Complete and Incomplete Reactions
6.9 Experiment: Precipitating Copper
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6.10 Elements
6.11 Elements near the Surface of the Earth
6.12 The Production of Iron and Aluminum
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By definition, pure substances are not broken up into different
components by those separation methods used to separate mixtures.
The aim of this chapter is to show that, in general, pure substances
can, nevertheless, be broken up by other means, such as applying
intense heat or an electric current. Conversely, such pure substances
(compounds) can also be synthesized from other pure substances,
but only by reacting in definite proportions.
Our first step is to decompose two pure substances by using heat
(Experiment 6.1) and electricity (Experiment 6.2). In each case,
new pure substances are produced that are quite different from the
original substances. We then reverse our method of attack and synthesize
compounds. The examples used are chosen to illustrate one of the
basic differences between compounds and mixtures: unlike mixtures,
compounds can be synthesized only by reacting them in definite proportions.
Early difficulties in the formation of the law of constant proportions
sprang in part from the difficulty of determining when a reaction
was complete. The reaction between copper and oxygen (Experiments
6.6 and 6.7) illustrates this circumstance: The investigation into
what has happened leads to an understanding of complete and incomplete
reactions.
Experiment 6.9 ends the sequence of experiments that started with
Experiment 6.6 and continued in Experiment 6.7; copper was made
to form a series of pure substances and was then recovered, suggesting
that the copper was there all along. The section leads into the
operational definition of elements (Section 6.10). The reasoning
used in the definition of an element is reinforced with two historical
examples. Be sure to spend enough time on this section.
Sections 6.11 and 6.12 balance the preceding discussion of scientific
methodology with a discussion of the abundance of elements near
the surface of the earth, and a description of the industrial process
of producing iron and aluminum. You can assign these sections for
reading, and follow up with a brief class discussion.
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CHAPTER 7
RADIOACTIVITY |
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7.1 Radioactive Elements
7.2 Radioactive Decomposition
7.3 Experiment: Radioactive Background
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7.4 Experiment: Collecting Radioactive Material on a Filter
7.5 Experiment: Absorption and Decay
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7.6 Radioactivity and Health
7.7 A Closer Look at Radioactivity
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Radioactivity, though often in the news, is a topic that mystifies
the public. Some students may have heard of alpha, beta, or gamma
rays before, but have no first-hand experience with any phenomena
related to them. In this course the distinction is irrelevant, and
should be avoided.
The objectives of this chapter are quite modest: learning the basics
about counting radioactive decays and noting the discreteness of
the process. Tying this discreteness to change of one element into
another suggests a particle model of matter. More than that, the
counting of radioactive decays provides us with a direct way of
counting the number of atoms in a measurable sample of an element,
thereby providing a means of finding the mass of atoms.
Unlike in other chapters, the three experiments in Chapter 7 are
to be done by the class as a whole rather than by pairs of students.
The reason is simple: it is unlikely that you will have enough Geiger
counters. However, if you have more than one counter, divide the
class into smaller groups and have them work in parallel. The class
will have the advantage of seeing that while the details vary, the
general trend is the same.
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CHAPTER 8
THE ATOMIC MODEL OF MATTER |
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8.1 A Model
8.2 Experiment: A Black Box
8.3 The Atomic Model of Matter
8.4 "Experiment": Constant Composition Using Fasteners
and Rings
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8.5 Molecules
8.6 Experiment: Flame Tests of Some Elements
8.7 Experiment: Spectra of Some Elements
8.8 Spectral Analysis
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8.9 "Experiment": An Analog for Radioactive Decay
8.10 Half-Life
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We now introduce the atomic model of matter, which will continue
to be at the center of our attention through Chapters 9, 11, and
12.
After a brief introduction to the meaning of a "model,"
the class applies the idea to a Black Box, which provides an opportunity
to make testable predictions (Experiment 8.2).
Sections 8.3-8.6 sum up key observations made earlier in the course
in the context of the atomic model. The law of Conservation of mass
and the law of Constant Proportions are given special attention.
The class experiments with spectra of atoms and is shown evidence
that the spectra present properties of the individual atoms rather
than properties of the elements in bulk.
Finally, the atomic model is used to predict the existence of a
Half-Life for radioactive elements.
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CHAPTER 9
THE SIZES AND MASSES OF MOLECULES AND ATOMS |
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9.1 The Thickness of a Thin Layer
9.2 Experiment: The Thickness of a Thin Sheet of Metal
9.3 Scientific Notation
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9.4 Multiplying and Dividing in Scientific Notation: Significant
Digits
9.5 Experiment: The Size and Mass of an Oleic Acid Molecule
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9.6 The Mass of Helium Atoms
9.7 The Mass of Polonium Atoms
9.8 The Size of Atoms
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This chapter greatly strengthens the atomic model of matter introduced
in Chapter 8. The ability to ascribe a mass and a size to atoms
in effect clinches the argument for the acceptance of the model.
However, the chapter does make heavier demands on your students'
mathematical skills than other chapters in the book.
Even though the steps of the experiments are conceptually very
simple, it takes a relatively long chain of operations with powers
of 10 to get the desired results. The details should be treated
only with a class that can go through the rather complex arithmetic
without losing sight of the physical content. With students who
are weak in mathematics, it may be advisable to treat the chapter
lightly. Carry them through a limited number of calculations on
the chalkboard, with the main goal being a basic understanding of
the method used to find the masses and sizes of atoms. For suggestions
on how to do this, see comments on Sections 9.6 through 9.8.
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CHAPTER 10
ELECTRIC CHARGE |
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10.1 Introduction
10.2 A Measure for the Quantity of Charge
10.3 Experiment: Hydrogen Cells and Light Bulbs
10.4 Experiment: Flow of a Charge at Different Points in
a Circuit
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10.5 The Conservation of Electric Charge
10.6 The Effect of the Charge Meter on the Circuit
10.7 Charge, Current, and Time
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10.8 Experiment: Measuring Charge
with an Ammeter and a Clock |
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In this chapter we introduce a model of electric charge flow, the
law of conservation of charge, and two methods for measuring charge.
The emphasis throughout this chapter and the next is on electric
charge rather than on electric current. It is important to keep
this in mind, even though from the end of this chapter on, we shall
measure moving charge indirectly by measuring current and time.
(See Section 10.8.)
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CHAPTER 11
ATOMS AND ELECTRIC CHARGE |
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11.1 The Charge per Atom of Hydrogen and Oxygen
11.2 Experiment: The Electroplating of Zinc
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11.3 The Elementary Charge
11.4 The Elementary Charge and the Law of Constant Proportions
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11.5 Experiment: Two Compounds of Copper
11.6 The Law of Multiple Proportions
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At the end of the preceding chapter we established a method of measuring
electric charge with an ammeter and a clock. We shall now use this
method to find the quantity of charge needed to plate out a single
atom of an element from a solution. The comparison of these charges
will lead us to the existence of a natural unit of charge, the elementary
charge. From this, the idea of "atoms" of electricity
can be related very directly to the law of constant proportions
studied in Chapters 6 and 8.
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CHAPTER 12
CELLS AND CHARGE CARRIERS |
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12.1 Experiment: The
Daniell Cell
12.2 Experiment: Zinc and Copper in Different Solutions
12.3 Flashlight Cells
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12.4 Unintentional Cells and Corrosion
12.5 The Motion of Electric Charge Through a Vacuum
12.6 Electrons
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12.7 Atoms and Ions
12.8 The Motion of Charge Through a Circuit
12.9 The Direction of Electric Current
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The first topic in this chapter is the Daniell cell and an investigation
of the basic reactions that make it work: dissolving zinc and plating
out copper. We then demonstrate that similar reactions occur in
other cells, both desirable ones and undesirable ones such as those
causing corrosion.
By now we have added a great deal to the phenomenological knowledge
of the students. We have shown how to use that knowledge to expand
the atomic model of matter to relate charge per atom to constant
composition, multiple proportions, and simplest formulas. However,
we have not shown how to connect the phenomena involving electric
charge with the mechanism of compound-forming (chemical) properties
of atoms. To be able to do that we need electrons. We use the passage
of charge through a vacuum tube to introduce electrons. In a sense,
the vacuum tube fulfills in this chapter a similar function to that
of radioactivity in Chapter 7. Using the vacuum tube to make the
existence of electrons plausible corresponds to using radioactivity
to make the existence of atoms plausible. Electrons and atoms are
then related through the introduction of positive and negative ions
to account for the movement of charge through a solution.
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