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Content Benchmark P.8.A.4
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Physical Science
Matter
  P.8.A.1
  P.8.A.2
  P.8.A.3
  P.8.A.4
  P.8.A.5
  P.8.A.6
  P.8.A.7
  P.8.A.8
Force and Motion
Energy
Content Areas
Nature of Science (NOS)
Life Science
Earth Science
Physical Science

Students know atoms often combine to form molecules, and that compounds form when two or more different kinds of atoms chemically bond. E/S

Molecules
An understanding of the nature of molecules provides an essential conceptual framework for future understanding of the physical and chemical properties of matter, and the physical and chemical changes that occur in matter. Atoms of most elements do not exist independently. They either form molecules or ions.

A molecule is the smallest particle of a substance that exists independently and retains the properties of that substance. A molecule is formed when two or more atoms chemically combine. Elements and compounds can form molecules. A compound is a molecule that contains at least two different elements or kinds of atoms. All compounds are molecules, but not all molecules are compounds. For example, molecular hydrogen (H2) is not a compound, and other molecular elements include oxygen (O2), nitrogen (N2), fluorine (F2), chlorine (Cl2), bromine (Br2), and iodine (I2).  Water (H2O), carbon dioxide (CO2) and glucose (C6H12O6) are compounds because each is made from more than one element.  Remember, the smallest unit of each of these substances is a molecule. Figure 1 is a diagram of a water molecule that contains one oxygen atom and two hydrogen atoms chemically bonded by sharing electrons.


Figure 1. Model of a water molecule
(From http://www.historyoftheuniverse.com/shelmod6.html)

To learn more about the difference between molecules and compounds, go to http://education.jlab.org/qa/compound.html

 
Ions
Ions are electrically charged atoms or molecules. If an atom or molecule has gained electrons, it has a negative charge. If an atom or molecule has lost electrons, it has a positive charge. The following diagram shows sodium (Na+) having a positive charge because it has given an electron to the chlorine, and thereby, gives the chorine (Cl-) a negative charge. The resulting opposite charges of the ions causes the formation of a bond between the two ions.


Figure 2.  A model of the ionic bond between sodium and chlorine in table salt.

For an animation of the formation of an ionic bond between sodium and chlorine visit http://www.promotega.org/UGA06004/ionic_bonds.html

 
Ionic Compounds
Metals often react with nonmetals to form ionic compounds. Ionic compounds have positive and negative ions formed by gaining or losing electrons, which in turn, forms neutral atoms and molecules. For example 2Na + Cl2 → 2NaCl. This equation can be restated as two atoms of sodium react with one diatomic molecule of chlorine to form two ions of sodium chloride. Individual molecules do not exist in ionic compounds. Instead the positive and negative ions are arranged in a specific pattern to form a unit called a crystal.

 

Figure 3. Sodium Chloride, an ionic compound
 (From http://www.americanchemistry.com/s_chlorine)

 
Molecular Compounds
Nonmetals combine with each other to form covalent compounds that exist as neutral molecules. For example 2H2 + O2 → 2H2O. This equation can be restated as two diatomic molecules of hydrogen react with one diatomic molecule of oxygen to form two molecules of water. In covalent bonding, electrons are shared. The electron clouds of the bonded atoms overlap. Figure 4 is the diagram of another covalent compound, methane, showing the sharing of electrons between one carbon atom and four hydrogen atoms.

gcsechem_106.gif

Figure 4.  A model of covalent bonding in methane molecule.
Each hydrogen atom can share one electron and the carbon atom can share four electrons.
(From http://www.bbc.co.uk/schools/gcsebitesize/science/images/gcsechem_106.gif)

To learn more about chemical compounds and covalent bonds, go to http://www.elmhurst.edu/~chm/vchembook/143Aioniccpds.html


Chemical Formulas
Chemical formulas can be subdivided into empirical formulas, molecular formulas, and structural formulas. Empirical formulas are based on the mass of the elements represented in the formula. This type of formula shows the relative number of atoms of each element in a compound. For example, in the ionic compound of sodium chloride (NaCl) the ratio of sodium (Na+) ions to Chlorine (Cl-) ions is one to one. Now consider the molecular compound glucose. The empirical formula for glucose is CH6O. This formula is written to indicate there is one carbon atom and one oxygen atom for every six atoms of hydrogen.

The molecular formula for glucose however, is C6H12O6. Molecularformulas show the actual number of atoms of each element in a molecule of a compound. Middle school students should become familiar with molecular formulas. Being able to identify the kinds and numbers of atoms in a molecular formula will allow them to take greater conceptual strides in understanding chemical formulas when they enter high school.

For a guide on determining molecular formula, go to http://pages.towson.edu/ladon/empiric.html

The third type of chemical formula the structural formula shows the number of atoms, their placement in a molecule, and the bonds between. The structural formula for glucose is shown in figure 5.

Structural Formula for Glucose
Figure 5.  Structural formula of a glucose molecule
(From http://www.purchon.com/biology/sugars.htm#glucose)

For more information about chemical formulas, go to http://www.science.uwaterloo.ca/~cchieh/cact/cl20/formula.html


Coefficients and Subscripts in Molecular Formulas
Three molecules of carbon dioxide are represented by the molecular formula 3CO2. In this formula the coefficient is represented by the number 3 preceding the C. The subscript is the small number two to the lower right of the O. With this molecule, there are three molecules, as indicated by the coefficient: with a total of three carbon atoms and six oxygen atoms (3 groups of oxygen pairs).  Students benefit greatly from both building and drawing molecules and matching them to their correct molecular formulas. Once they have mastered this they are ready to build models for chemical reactions.

More information about coefficients and subscripts, and their use in balancing chemical equations, can be found at
http://dbhs.wvusd.k12.ca.us/webdocs/Equations/Balance-Equation.html


Properties of Matter
Atoms are recycled. They come together and bond to form molecules. When those molecules decompose, the same atoms rearrange with other atoms to form new molecules. The chemical make-up of a substance formed when bonding occurs determines what the physical and chemical properties of that substance will be.  The properties or characteristics of matter are generally divided in two groups: physical and chemical. Whereas chemical composition cannot directly be observed, we can use our senses to observe properties. From our observation of the properties of a substance, we can infer the chemical nature of the substance.


Physical Properties of Matter
Physical properties do not change the chemical structure or composition of matter. Altering physical properties will not change the basic nature of the atom or molecule. Physical properties can be determined both quantitatively and qualitatively. Quantitative properties can be measured and include quantities such as distance, mass, and time. Qualitative properties are those that can be observed using our senses of smell, taste, sight, hearing, and touch. Examples of qualitative properties include odor, color, and texture.

Groups of elements are often categorized by their common properties. For example, metals are generally described by their tendency to share the physical properties of a shiny luster, ductility, malleability and being good conductors of heat and electricity.  The table below provides a partial list of common physical properties of matter. This list has been limited to those properties most likely to be observed and discussed within the middle school classroom.


Common physical properties of matter


Mass

Volume

Density/Specific gravity

Melting/Freezing point

Boiling/Condensing point

Texture

Color

Odor

Solubility/Dissolving

Polarity

Appearance

Specific heat

Conductivity

Viscosity

Surface tension

Malleability

Ductility

Electrical conductivity

Thermal conductivity

Hardness

Luster

Elasticity

Attraction or repulsion of magnets

Ability to transmit light (transparency/translucency/opacity)



Chemical Properties of Matter

Chemical properties do change the chemical structure of matter. More specifically, chemical properties refer to the ability of matter to undergo chemical reactions to form new substances. Below is a list of some common chemical properties of matter.

Chemical Properties of Matter

Reactivity with water

Reactivity with oxygen

Reactivity with metals

pH/reactivity with acid or base

Electromotive force

Flammability/Heat of combustion

Oxidation

Reduction



Physical Changes
Physical changes take place without any change in molecular composition. The same elements or compounds are present before and after the change. The same molecules are present through out the change. Physical changes are related to physical properties.

Changes in the state of matter are physical changes. To learn more about the states of matter and how the change from one state to another, go to MS TIPS Benchmark P.8.A.1. Another form of physical change is the separation or combination of substances without affecting their chemical composition. You can stir, crush, cut, tear, dissolve, and smash a substance without changing the fundamental composition of the substance, the molecule being that substance in the case of bonded atoms.


Chemical Changes

Chemical changes alter the composition of the original matter. A different arrangement elements or compounds are present at the end of the chemical change. In other words, in a chemical change, a chemical reaction has occurred. The atoms in molecules/compounds are rearranged to make new and different molecules/compounds.

Some chemical changes are reversible, but more often, they are difficult to reverse or cannot be reversed. Chemical changes may also be accompanied by such characteristics as a color change, different odor being given off, and light being emitted. Other characteristics can be popping or fizzing sounds due to the release of gas and/or the release or absorption of heat. Endothermic reactions are those that absorb or require heat, such as baking a cake or photosynthesis. Exothermic reactions release heat to the surroundings, such as the reaction between calcium chloride and water or when a substance is burned.

The rate at which a chemical reaction occurs can be affected by a number of variables including temperature, concentration, amount, surface area, stirring, and the presence or absence of a catalyst. Catalysts are substances that can either increase or decrease the rate at which a chemical reaction occurs without being changed by the chemical reaction. Enzymes are examples of catalysts that facilitate chemical reactions in the human body and other living organisms.

To learn more about the difference between chemical and physical changes, go to http://www.chem4kids.com/files/matter_chemphys.html


Chemical Reactions and Changes in pH (acids, bases, and neutralization).

Acids and bases are most commonly identified by their properties. The following table summarizes these properties.

Acids

Bases

Taste sour

Taste bitter

Turn blue litmus red

Turn red litmus blue

Have a pH below 7

Have a pH above 7

Are corrosive

Are corrosive

Conduct electricity

Conduct electricity

Generate H+ ions in solution

Generate OH- ions in solution

React with metals

Feel slippery

As an acid dissolves in water, its molecules separate and hydrogen ions (H+) are produced. The H+ ions then combine with water (H2O) to form hydronium ions (H3O+). As a base dissolves in water, its molecules separate and hydroxide ions (OH-) are produced.  Pure water (HOH) is neutral. The following equation shows the reaction between hydronium and hydroxide ions to produce pure water:  H3O+ + OH- → 2H2O.

To learn more about how acids and bases react in water, go to http://www.iun.edu/~cpanhd/C101webnotes/chemical%20reactions/acidbase.html

Some common acids include vinegar and citric acid. Common bases include ammonia and baking soda. Care should be taken to ensure that students understand that not all substances that contain H are acids, and not all substances that contain OH are bases. For example, sugar (C6H12O6) contains H and OH, but because sugar molecules do not ionize in water, they are not acidic or basic. The following diagram shows the dissolving of an acid and a base and subsequent formation of ions in water.

Hydrochloric acid (HCL)
dissolved in water
Sodium hydroxide (NaOH)
dissolved in water 

H+         Cl-
 Cl-   H+     

H+       Cl-

Na+     OH-  
      OH-  
Na+
   Na+  OH-

A substance that changes color in the presence of an acid or base is an indicator. Indicators vary in their ability to react with concentrations of acids or bases. Litmus is a common indicator used to identify acids and bases. Litmus turns blue in the presence of a base and red in the presence of an acid.  Some common household substances can be used as acid-base indicators, including:  (1) red cabbage juice, (2) beet juice, (3) grape juice, (4) berry juices, and (5) red onion juice. These substances work as indicators because they contain anthocyanin pigments that dissolve in water and their color is dependent upon the level of acidity.  Anthocyanin pigments in plants are generally not seen due to the presence of chlorophyll which is green except in the fall when chlorophyll breaks down and their red, blue and purple colors become visible.

More about natural acid and base indicators are found at
http://antoine.frostburg.edu/chem/senese/101/acidbase/faq/natural-indicators.shtml

Indicators can identify substances as acids or bases but to determine how acidic or basic a solution is the pH scale is used. pH stands for power of hydrogen and is a measure of the concentration of hydronium ions (H3O+) in a solution. The pH scale ranges from 0-14. A pH of 7 is neutral (neither acid nor base). A pH below 7 is acid and a pH above 7 is base. The scale is logarithmic, so each number represents a difference 10 times greater or smaller than the previous number. For example, a solution with a pH of 8 would be 10 times more basic than a neutral solution with a pH of 7. Figure 6 summarizes the pH scale, some common examples of substances at each pH level, and the affects of an acid or base on the environment.


Figure 6. The pH scale with some common substances.
(From http://www.elmhurst.edu/~chm/vchembook/184ph.html)

Chemical reactions can result in pH changes.  A neutralization reaction takes place when acids and bases react with each other to produce a salt and water. The H+ ions of the acid and the OH- ions of the base react to form water. Acids can be added to bases to lower the pH and bases can be added to acids to raise the pH. Many commercial chemicals are designed to affect pH changes. For example, antacids are used to raise the pH in the stomach. Acid is also used to neutralize lime deposits on and in pipes.


Acid Rain

One way humans affect chemical changes in the environment is by the burning of fossil fuels. The burning of high-sulfur coal releases sulfur dioxide (SO2) into the atmosphere. When sulfur dioxide dissolves in water sulfuric acid (H2SO3) forms. Oxides of nitrogen (NOx) are released into the atmosphere from vehicle engines and power plants. When nitrogen dioxide dissolves in atmospheric water vapor, nitric acid forms.  These acids return to the earth in precipitation (rain, snow or fog) and cause a decrease in the pH of bodies of water and soil, which in turn adversely affects living organisms. These acids also dissolve the calcium carbonate in the limestone of statues, monuments and buildings, causing physical damage.

To learn more about acid rain, go to http://www.epa.gov/acidrain/

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Content Benchmark P.8.A.4

Students know atoms often combine to form molecules, and that compounds form when two or more different kinds of atoms chemically bond. E/S

 
Common misconceptions associated with this benchmark

1. Students commonly fail to differentiate between atoms and molecules and also, between elements and compounds.

Students need to explore atoms, molecules, elements and compounds in-depth in order to confidently differentiate among these fundamental substances. The smallest particle of an element, and also that retains the properties of that element, is an atom. The smallest particle of a compound, and also that retains the properties of that compound, is a molecule. The atoms of many elements form diatomic molecules. For example, a diatomic molecule of oxygen (O2) contains two oxygen atoms that are covalently bonded. Atoms combine to form molecules and elements combine to form compounds. The concept map below summarizes the relationship between the fundamental building blocks of matter.

 
                                     
For a listing of this misconception and other student misconceptions about matter, visit the Operation Physics American Institute of Physics website at http://www.amasci.com/miscon/opphys.html


2. Students frequently fail to relate the properties of pure substances to the behavior of
certain types of particles.

During typical science lab investigations into chemical changes, students use their senses to observe the signs of chemical change. Often, the investigation is followed by making a list of the chemical and physical properties observed. Students then memorize the list of properties without making the connection between those properties and what is happening at the particle level during the reaction. Lesson plans should consistently be designed to lead students to make connections between what they observe about a substance and what is happening at the particle level. Having students memorize physical and chemical properties of matter without making this connection often results in their viewing the study of atoms and molecules as independent of the properties of matter they observe in their daily interactions with substances and chemical reactions.

More information about this misconception, along with a free on-line publication dealing with chemistry misconceptions, can be found at http://www.rsc.org/education/teachers/learnnet/miscon2.htm


3. Students often incorrectly think that the formation of new substances just happens rather than resulting from particle rearrangement.

Students often mistakenly perceive the products of a chemical reaction as existing in addition to the reactants, rather than being formed by the rearrangement of the atoms and molecules of the reactants. For example, students might view the reactants of the photosynthesis process (water and carbon dioxide) as existing independently of the products of the reaction (glucose and oxygen). They believe that the glucose and oxygen are formed from different atoms than those that compose the water and carbon dioxide. Using models to build the reactants of a chemical reaction atom by atom and then rearranging those atoms to build the products provides students with concrete evidence of particle rearrangement.

For more details on misconceptions associated with chemical reactions, go to http://educ.queensu.ca/~science/main/concept/chem/c07/C07CDTL1.htm


4. Students perceive particles as being created or destroyed during chemical changes.

The Law of Conservation of Mass is very difficult for students to understand. Many students memorize the definition, but do not apply it to specific chemical changes. For example, when things burn or an explosion occurs, students often incorrectly believe that matter is destroyed. In addition to building the reactants out of atom models and rearranging them to form the products, some chemical reactions can be conducted on a balance to show that mass is conserved. For example, putting a balloon containing baking soda over a flask containing vinegar and then tipping the balloon up so the baking soda falls into the vinegar. Since the reactants and products are contained within a closed system the balance will show no change in mass.

More information about misconceptions related to the conservation of mass and chemical reactions can be found at http://intro.chem.okstate.edu/ChemSource
/ChemRx/chemrx11.htm#Com

For a more detailed discussion of the Law of Conservation of Mass refer to
MS TIPS Benchmark P.8.A.5.


5. Students often believe that all acids are strong and will burn through things

Students often think of acids only in terms of chemicals used in a laboratory. They also think of acids in terms of their ability to “eat” through skin, clothing, metal, and wood, etc. Although acids do react with metals and are defined as corrosive, students need to understand that acids are defined by the presence of H+ ions and vary in concentration. 

For teacher tips on addressing student misconceptions related to the behavior of acids and bases visit http://www.okstate.edu/jgelder/acidPage10.html#teacherlab


6. Many students think that with acids and bases, strength and concentration mean the
same thing.

Acids and bases are defined as strong or weak based on the number of molecules that separate and ionize when dissolved in water. More specifically, strength refers to the number of H+ and OH- ions present in the solution. Hydrochloric acid is a strong acid and citric acid is a weak acid. Sodium hydroxide is a strong base and ammonia is a weak base. Concentration refers to the amount of acid or base that is dissolved in water.

An excellent site that discusses student difficulties with acids and bases, and more generally, chemical reaction is found at
http://www.education.vic.gov.au/studentlearning/
teachingresources/science/scicontinuum/l5physchem.htm

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Content Benchmark P.8.A.4

Students know atoms often combine to form molecules, and that compounds form when two or more different kinds of atoms chemically bond. E/S

Sample Test Questions

1st Item Specification: Understand physical and chemical properties

Depth of Knowledge Level 1

  1. Which of the following is a chemical property of matter?
    1. Melting
    2. Magnetism
    3. Flammability
    4. Density
  1. Which of the following is a physical property of matter?
    1. Melting
    2. Flammability
    3. Reacting with water
    4. Fizzing in vinegar

Depth of Knowledge Level 2

  1. Maria is conducting an investigation to identify the properties of an unknown powder. She mixes the powder with vinegar. Which of the following observations made by Maria shows a physical and a chemical property of the white powder?
    1. The powder is white and has a grainy texture before the reaction.
    2. The vinegar begins fizzing when the powder is added and the temperature is lower.
    3. The vinegar is clear and the powder is white before they are combined.
    4. The vinegar is a liquid and the powder is a solid before they are combined.
  1. Luann is conducting an investigation to compare two liquids. One of the liquids is water, the other is alcohol. Luann’s data are shown on the table below.

Luann’s data

Liquid A

Liquid B

Clear

Clear

Colorless

Colorless

Boils at 100°C

Boils at 79°C

Extinguishes a flame

Burns

Which two properties above most likely identify the water?

  1. Clear and burns.
  2. Boils at 79°C and burns.
  3. Colorless and clear.
  4. Colorless and boils at 100°C.
  1. Jose is conducting an experiment to investigate the properties of an unknown powder. Jose’s observations are listed on the data table below:

 

Observations of unknown powder

1

The powder melts when heated.

2

The powder has large, white, crystals.

3

The powder dissolves in water.

4

The powder reacts with acid.

Which of the following shows a physical and a chemical property of the powder?

    1. The powder melts when heated and dissolves in water.
    2. The powder dissolves in water and reacts with acid.
    3. The powder melts and has large, white crystals.
    4. The powder dissolves in water and has large, white, crystals.

 
2nd Item Specification: Understand physical and chemical changes and identify evidence of chemical changes (e.g., releasing heat, absorbing heat, and producing gas).

Depth of Knowledge Level 1

  1. Which of the following is evidence that a chemical change has occurred?
    1. Water bubbling when it starts to boil.
    2. Detergent removing grease from a dish.
    3. Sugar turning black when it burns.
    4. Oil and vinegar separating in salad dressing
  1. Which of the following is the BEST example of a chemical change?
    1. Apples turning brown as they decompose or rot.
    2. Sugar cubes dissolving when they are put in water.
    3. A glass breaking when it falls from a table.
    4. Melted butter turning to solid when it cools.

Depth of Knowledge Level 2

  1. Which of the following is evidence that a chemical change is occurring?
    1. Cherry drink mix is added to water and the resulting solution is red.
    2. A white powder is added to cool tap water in a beaker and the beaker gets hot.
    3. Water is added to coffee until the solution becomes clear.
    4. Water is added to sand and the sand looks darker
  1. Use drawings #1-4 to answer the question below.

 

Which drawing is most likely a compound produced by a chemical change?

    1. Drawing 1
    2. Drawing 2
    3. Drawing 3
    4. Drawing 4
  1. Marianne and Paul conducted several physical and chemical tests on a piece of metal in their science class. Their observations appear on the data table below.

Observations of metal during physical and chemical tests

Flattened into a thin sheet when pounded with a hammer.

Melted when placed in a hot flame.

Produced bubbles of gas when dropped into acid.

Conducted electricity when attached to a battery.

Produced salt when combined with a nonmetal.

Which of the following identifies both a physical AND a chemical change to the metal?

    1. Flattening into a thin sheet and melting.
    2. Melting and conducting electricity.
    3. Conducting electricity and producing bubbles of gas.
    4. Producing bubbles of gas and producing salt.


3rd Item Specification: Given a chemical formula, identify the number and type of atoms in a molecule.

Depth of Knowledge Level 1

  1. Which element is contained in all of the following chemical compounds?

Compounds:  CO2, NaHCO3, C6H12O6 and C4H10.

  1. Hydrogen.
  2. Oxygen.
  3. Carbon.
  4. Sodium
  1. The chemical formula for two molecules of water is 2H2O. Identify the kinds and numbers of atoms in two water molecules.
    1. Two hydrogen atoms and one oxygen atom.
    2. Two hydrogen atoms and two oxygen atoms.
    3. Four hydrogen atoms and four oxygen atoms.
    4. Four hydrogen atoms and two oxygen atoms

Depth of Knowledge Level 2

  1. The formula for two molecules of the simple sugar glucose is 2C6H12O6. Two molecules of glucose contain
    1. 2 kinds of atoms and 24 total atoms.
    2. 3 kinds of atoms and 2 total atoms.
    3. 3 kinds of atoms and 48 total atoms.
    4. 24 kinds of atoms and 3 total atoms.
  1. One molecule of iron oxide or rust contains two atoms of iron and three atoms of oxygen. Which of the following formulas represents rust?
    1. 2FeO2
    2. Fe2O3
    3. FeO
    4. HOI

  2. Which of the following pairs of compounds contain the same number of atoms, but different kinds of atoms?
    1. CO2 and CaCl2.
    2. CO2 and CO.
    3. MgCO3 and 2CaCO3.
    4. C4H10 and C5H12.

4th   Item Specification: Understand that chemical reactions can result in a pH change (acids, bases, and neutralizations).

Depth of Knowledge Level 1

  1. Pure water is neutral and has a pH of 7. When lemon juice is added to water the pH will become lower than 7 and turns litmus paper red. Lemon juice is
    1. a salt.
    2. an acid.
    3. a base.
    4. neutral.
  1. Which of the following is evidence that a chemical change has occurred?
    1. A change in acidity
    2. A change in shape
    3. A change in size
    4. A change in mas

Depth of Knowledge Level 2


  1. Lee has three clear liquids, labeled liquid A, B, and C. One is an acid, one is a base, and one is pure water, but he is not sure which is which. Lee has made the following observations about the three liquids.
  • liquid B does not change the color of litmus paper.
  • When liquids A and B are mixed, the solution turns litmus paper pink.
  • When liquids A and C are mixed, the solution does not change the color of litmus paper.
  • Which of the following statements is true about the liquids?

      1. Liquid C is an acid and liquid A is water.
      2. Liquid B is an acid and liquid C is water.
      3. Liquid A is an acid and liquid B is a base.
      4. Liquid A is an acid and liquid B is water.
    1. Marla’s teacher gave her some baking soda. She added a liquid to the baking soda and a reaction occurred. She asked Marla to find out if the liquid was an acid or a base. Marla tested the new substance with litmus paper. She decided that an acid had reacted with the baking soda. Which of the following evidence would support Marla’s conclusion that an acid was present?

      1. The new substance did not change the color of litmus paper.
      2. The new substance turned the litmus paper pink.
      3. The new substance turned the litmus paper blue.
      4. The new substance turned the litmus paper white.

    Constructed Response P.8.A.4

    1. Matthew’s teacher gave him a piece of iron and asked him to determine some physical and chemical properties of the metal. Matthew’s observations are on the table below:

    Physical and chemical properties of iron

    Conducts electricity.

    Reacts with acid.

    Reacts with oxygen in the air to form rust.

    Attracts to a magnet.

    Matthew’s teacher wants him to organize the properties as either physical or chemical. Below is the data table Matthew made for this purpose.

    1. Identify the properties as physical or chemical by writing each one on the Matthew’s data table.

    Physical properties

    Chemical properties

     

     

     

     

     

     

    1. Justify why you categorized each property as either a physical and chemical property

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    Content Benchmark P.8.A.4

    Students know atoms often combine to form molecules, and that compounds form when two or more different kinds of atoms chemically bond. E/S

    Answers to Sample Test Questions

    1. C, DOK level 1
    2. A, DOK level 1
    3. B, DOK level 2
    4. D, DOK level 2
    5. B, DOK level 2
    6. C, DOK level 1
    7. A, DOK level 1
    8. B, DOK level 2
    9. B, DOK level 2
    10. C, DOK level 2
    11. C, DOK level 1
    12. D, DOK level 1
    13. C, DOK level 1
    14. B, DOK level 2
    15. A, DOK level 2
    16. B, DOK level 1
    17. A, DOK level 1
    18. D, DOK level 2
    19. B, DOK level 2

    Constructed Response 3-point Answer and Score Rubric:

    Physical properties

    Chemical properties.

    Conducts electricity

    Reacts with acid.

    Attracted to a magnet

    Reacts with oxygen in the air to form rust.


     3 points

    Response addresses all parts of the question clearly and correctly.

    Physical properties are characteristics of a substance that do not involve a chemical change, or change in the structure of the molecules and/or compounds. Chemical properties are characteristics of a substance that describe the substance’s ability to participate in chemical reactions. The structure of the molecules and/or compounds is changed. Reacts with acid and reacts with oxygen are chemical.

    Attracted to a magnet and conducts electricity are physical. Physical properties do not change the structure of matter. (The iron is not changed into a new substance.) Chemical properties do change the structure of matter. (A chemical change occurs or the iron combines with other atoms to make a new substance)

    2 points

    Response addresses all parts of the question and includes only minor errors.

    1 point

    Response does not address all parts of the question.

    0 points

    Response is totally incorrect or no response provided.


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    Content Benchmark P.8.A.4

    Students know atoms often combine to form molecules, and that compounds form when two or more different kinds of atoms chemically bond. E/S


    Intervention Strategies and Resources

    The following is a list of intervention strategies and resources that will facilitate student understanding of this benchmark.

    1. Structure of Matter

    TutorVista has a comprehensive website that covers many chemistry topics, including chemical and physical changes and acid-base reactions. The site is intended as a tutorial for high school students, but much of the information is appropriate for middle school. The site could be used to supplement homework and prepare students for quizzes and tests.

    To access the chemistry section of the site, including excellent animations, visit
    http://www.tutorvista.com/content/chemistry/chemistry-i/
    chemical-reactions/chemical-reactionsindex.php


    2. Matter Lesson Plans

    The Mathematics and Science Activity Center has a database rich in information and lesson plans about the structure and nature of matter. This site has the added dimension of accessing information specifically by state.

    For access to these lessons visit http://edinfo.securesites.net/math_science/


    3. Visual Approach to Teaching Ionic Compounds

    David Harazin from Jamieson Elementary School in Chicago, Illinois offers a lesson plan for teaching an understanding of how ionic compounds form. This lesson is very visual and easy to understand and implement.

    For access to this lesson plan that uses a visual approach to understand atomic structure and bonding visit http://www.iit.edu/~smile/ch9308.html


    4. Graphic Representation of Covalent Bonding

    The National Health Museum has an excellent graphics gallery that provides easily understood examples of ionic and covalent bond formation.

    To access this website for information about bonding, plus free PowerPoint templates and downloadable demonstrations visit http://www.accessexcellence.org/RC/VL/GG/ecb/covalent_ionic_bonds.php


    5. Physical and Chemical Properties

    Indiana University Northwest provides a basic review of the meaning of the physical and chemical properties of matter. A highlight of this website is an image of the periodic table that can be clicked on to access the elements and their individual properties.

    The Indiana University website address is
    http://www.iun.edu/~cpanhd/C101webnotes/matter-and-energy/properties.html

    Elmhurst College offers a website known as The Virtual Chembook. This site provides a concise review of physical and chemical properties and physical and chemical changes. Very clear and informative pictures are also included.

    The website can be accessed at http://www.elmhurst.edu/~chm/vchembook/105Achemprop.html


    6. Physical and Chemical Changes Activities and Resources

    Saskatchewan Schools in California have a colorful and interactive lab with video clips and extensions.

    To access their chemistry section visit http://www.saskschools.ca/curr_content/science9/chemistry/lesson8.html

    Quia website has flashcards, a word search, and matching and concentration games to help reinforce vocabulary related to physical and chemical properties and changes.

    Visit the website at http://www.quia.com/jg/540845.html

    The State of Utah, Office of Education offers several activities that include video clips, animations, and pictures related to physical and chemical properties and changes. This site is targeted specifically for middle school physical science students.

    To access these activities visit http://www.schools.utah.gov/curr/science/c
    ore/8thgrd/sciber8/matter/html/intro.htm


    7. Acid & Base pH Lab

    Hampshire County Schools in West Virginia offers an acid and base lab using household substances. A variety of techniques including a lab activity, Venn diagram and a concept map to teach the concepts of acid, base, and pH are presented. A data table is also included.
    Access this activity at http://rms.hamp.k12.wv.us/alkire/pHlab.html

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