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					Middle School Science                                                Physical and Chemical Changes
Movement of Energy Through Living and Non-Living Systems;                             Unit Outline
Matter, Its Structure and Changes; From Atoms to the Universe


                                    SC070300 Unit Outline

   Movement of Energy Through Living and Non-Living Systems;
   Matter Its Structure and Changes; From Atoms to the Universe

                       Unit 3: Physical and Chemical Changes

                                                Abstract
In this physical science unit students explore physical and chemical changes in matter and learn
to distinguish between them. Through observation and experimentation they learn that chemical
changes create new products and that only the motion and arrangement of molecules are altered
during physical changes.




January 29, 2004                                                       SCoPE SC070300 Page 1 of 6
Middle School Science                                                   Physical and Chemical Changes
Movement of Energy Through Living and Non-Living Systems;                                Unit Outline
Matter, Its Structure and Changes; From Atoms to the Universe

Lesson 1 – What Sort Are You? (SC070301)
Students sort a set of objects several times, using different properties each time. They develop an
understanding of different sorting methods and define physical properties.

Lesson 2 – Does Density Matter? (SC070302)
Students find the mass and volume of boxes containing different substances. They calculate the
density of the boxes. Students examine density as a characteristic physical property.

Lesson 3 – Mystery Objects (SC070303)
Students analyze the properties of soda pop cans to investigate how floating and sinking depend
on density. They reinforce their understanding that a physical property can be used to identify a
substance.

Lesson 4 – Mystery Liquids (SC070304)
In this lesson students transfer their understanding of density to liquids. Students identify water
by density and distinguish it from three other liquids using this physical property.

Lesson 5 – What is Matter Made Of? (SC070305)
Students learn how atoms and molecules make up all of the substances they see around them.
They relate the arrangement and motion of molecules to the physical properties of water.

Lesson 6 – Mixing It Up (SC070306)
In the first part of this lesson students make and separate mixtures. They verify that mixing is a
physical change that does not change the properties of the substances by separating the
substances. In the second part, students investigate several mixtures and relate their properties to
the size of particles in the mixture. They find examples of mixtures in everyday life.

Lesson 7 – Dissolved But Not Forgotten (SC070307)
Students explore the physical change of dissolving by making and separating solutions of salt,
sugar, and baking soda in water. They consider what molecules of a solution would be like and
how they would move.

Lesson 8 – Molecules in Changes of State (SC070308)
Students learn to explain the physical changes of evaporation, condensation, melting, and
freezing in terms of molecules. They melt various substances, investigate ways to speed up the
evaporation of rubbing alcohol, distill water, and create a “mini-water cycle.”

Lesson 9 – Investigating Powders (SC070309)
Students use indicators on four powders to investigate chemical changes. Through their
investigation, they observe both physical and chemical properties. Students learn that substances
react differently, and in characteristic ways, to chemical indicators.




January 29, 2004                                                          SCoPE SC070300 Page 2 of 6
Middle School Science                                                 Physical and Chemical Changes
Movement of Energy Through Living and Non-Living Systems;                              Unit Outline
Matter, Its Structure and Changes; From Atoms to the Universe

Lesson 10 – Sorting Liquids by a Chemical Property (SC070310)
Students use pH paper on several solutions as a chemical indicator for the strength of acids or
bases. These tests are additional evidence that substances have chemical properties as well as
physical properties.

Lesson 11 – Do Molecules Change Their Nature? (SC070311)
Students see additional instances of chemical changes. They identify chemical properties and
review the distinction between chemical changes and physical changes, both in terms of the
production of new substances and changes in molecules.

Lesson 12 – Rusty or Shiny? (SC070312)
Students investigate variables that effect chemical change. They reinforce the idea that chemical
changes produce permanent alternations in molecules and in chemical properties. Students also
review their understanding of a controlled experiment, variables and scientific method by
practicing experimental design.

Michigan Science Benchmarks
Design and conduct scientific investigations (I.1.MS.2).
Key Concepts: The process of scientific investigations – test, fair test, hypothesis, theory,
evidence, observations, measurements, data, conclusion. Forms for recording and reporting data
– tables, graphs, journals.

Real-World Contexts: Any in the section on Using Scientific Knowledge; also, recognizing
differences between observations and inferences; recording observations and measurements of
everyday phenomena.

Use metric measurement devices to provide consistency in an investigation (I.1.MS.4).
Key Concepts: Documentation – laboratory instructions. Measurements units – milliliters, liters,
millimeter, centimeter, meter, gram.

Measurement Tools: Balancing devices, measuring tape, thermometer, graduated cylinder.

Real-World Contexts: Conducting investigations, following or altering laboratory instructions for
mixing chemicals.

Evaluate the strengths and weaknesses of claims, arguments, or data (II.1.MS.1).
Key Concepts: Aspects of arguments such as data, evidence, sampling, alternate explanation,
conclusion; interference, observation.

Real-World Contexts: Deciding between alternate explanations or plans for solving problems;
evaluating advertising claims or cases made by interest groups; evaluating sources of references.




January 29, 2004                                                       SCoPE SC070300 Page 3 of 6
Middle School Science                                               Physical and Chemical Changes
Movement of Energy Through Living and Non-Living Systems;                            Unit Outline
Matter, Its Structure and Changes; From Atoms to the Universe

Describe and compare objects in terms of mass, volume, and density (IV.1.MS.1).
Key Concepts: Units of density – grams per cubic centimeter or grams per milliliter.

Measurement Tools: Balance, measuring cup or graduated cylinder, metric ruler.

Real-World Context: Common objects and substances.

Describe common physical changes in matter: evaporation, condensation, sublimation,
thermal expansion and contraction (IV.2.MS.1).
Key Concepts: States of matter – solid, liquid, gas. Processes that cause changes of state of
thermal effects: heating, cooling. Boiling. Mass/weight remains constant during physical
changes in closed systems.

Real-World Contexts: States of matter – solid, liquid, gas. Changes in state, such as water
evaporating as clothes dry, condensation on cold window panes, disappearance of snow or dry
ice without melting; expansion of bridges in hot weather, expansion and contraction of balloons
with heating and cooling; solid air fresheners.

Describe common chemical changes in terms of properties of reactants and products
(IV.2.MS.2).
Key Concepts: Common chemical changes – burning, rusting iron, formation of sugars during
photosynthesis, acid reacting with metal and other substances. Mass/weight remains constant in
closed systems.

Real-World Contexts: Chemical changes – burning, photosynthesis, digestion, corrosion, acid
reactions, common household chemical reactions such as with alkaline drain cleaners.

Explain physical changes in terms of the arrangement and motion of atoms and molecules
(IV.2.MS.3).
Key Concepts: Molecular descriptions of states of matter. Changes in state of matter – melting,
freezing, evaporation, condensation; thermal expansion and contraction. Speed of molecular
motion – moving faster, slower, vibrate, rotate, unrestricted motion; change in speed of
molecular motion with change in temperature.

Real-World Contexts: See examples of physical changes of matter.




January 29, 2004                                                      SCoPE SC070300 Page 4 of 6
Middle School Science                                                        Physical and Chemical Changes
Movement of Energy Through Living and Non-Living Systems;                                     Unit Outline
Matter, Its Structure and Changes; From Atoms to the Universe


National Science Education Standards

                                      Key ideas related to this unit

 National Science Education Standards                      When students first begin to understand
                                                           atoms, they cannot confidently make the
 o A substance has characteristic                          distinction between atoms and molecules or
   properties, such as density, a boiling                  make distinctions that depend upon it –
   point, and solubility, all of which are                 among elements, mixtures, and compounds,
   independent of the amount of the                        or between "chemical" and "physical"
   sample. A mixture of substances often                   changes. An understanding of how things
   can be separated into the original                      happen on the atomic level – making and
   substances using one or more of the                     breaking bonds – is more important than
   characteristic properties.                              memorizing the official definitions (which
                                                           are not so clear in modern chemistry
 o Substances react chemically in                          anyway). Definitions can, of course, be
    characteristic ways with other substances              memorized with no understanding at all.
    to form new substances (compounds)
    with different characteristic properties.              Going into details of the structure of the
    In chemical reactions, the total mass is               atom is unnecessary at this level, and
    conserved. Substances often are placed                 holding back makes sense. By the end of the
    in categories or groups if they react in               8th grade, students should have sufficient
    similar ways; metals is an example of                  grasp of the general idea that a wide variety
    such a group.                                          of phenomena can be explained by
Project 2061 Benchmarks for Science                        alternative arrangements of vast numbers of
Literacy                                                   invisibly tiny, moving parts. Possible
                                                           differences in atoms of the same element
The structure of matter is difficult for this              should be avoided at this stage. Historically,
grade span. Historically, much of the                      the identical nature of atoms of the same
evidence and reasoning used in developing                  element was an assumption of atomic theory
atomic/molecular theory was complicated                    for a very long time.
and abstract. In traditional curricula too,
very difficult ideas have been offered to                  When isotopes are introduced later, to
children before most of them had any                       explain subsequent observations, they can be
chance of understanding. The law of definite               a surprise and a lesson in the nature of
proportions in chemical combinations, so                   progress in science. The alternative –
obvious when atoms (and proportions) are                   teaching atoms' variety at the same time as
well understood, is not likely to be helpful at            the notion of their identity – seems likely to
this level. The behavior of gases – such as                be prohibitively confusing to most students.
their compressibility and their expansion
with temperature – may be investigated for                 To that end, students should become
qualitative explanation; but the mathematics               familiar with characteristics of different
of quantitative gas laws is likely to be more              states of matter – now including gases – and
confusing than helpful to most students.                   transitions between them. Most important,


January 29, 2004                                                               SCoPE SC070300 Page 5 of 6
Middle School Science                                                         Physical and Chemical Changes
Movement of Energy Through Living and Non-Living Systems;                                      Unit Outline
Matter, Its Structure and Changes; From Atoms to the Universe
students should see a great many examples                  • Atoms and molecules are perpetually in
of reactions between substances that                       motion. Increased temperature means
produce new substances very different from                 greater average energy of motion, so most
the reactants. Then they can begin to absorb               substances expand when heated. In solids,
the rudiments of atomic/molecular theory,                  the atoms are closely locked in position and
being helped to see that the value of the                  can only vibrate. In liquids, the atoms or
notion of atoms lies in the explanations it                molecules have higher energy, are more
provides for a wide variety of behavior of                 loosely connected, and can slide past one
matter. Each new aspect of the theory should               another; some molecules may get enough
be developed as an explanation for some                    energy to escape into a gas. In gases, the
observed phenomenon and grasped fairly                     atoms or molecules have still more energy
well before going on to the next.                          and are free of one another except during
                                                           occasional collisions.
By the end of the 8th grade, students should
know that                                                  • Scientific ideas about elements were
                                                           borrowed from some Greek philosophers of
• All matter is made up of atoms, which are                2,000 years earlier, who believed that
far too small to see directly through a                    everything was made from four basic
microscope. The atoms of any element are                   substances: air, earth, fire, and water. It was
alike but are different from atoms of other                the combinations of these "elements" in
elements. Atoms may stick together in well-                different proportions that gave other
defined molecules or may be packed                         substances their observable properties. The
together in large arrays. Different                        Greeks were wrong about those four, but
arrangements of atoms into groups compose                  now over 100 different elements have been
all substances.                                            identified, some rare and some plentiful, out
                                                           of which everything is made. Because most
• Equal volumes of different substances                    elements tend to combine with others, few
usually have different weights.                            elements are found in their pure form.




January 29, 2004                                                               SCoPE SC070300 Page 6 of 6

				
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