I.    7th Grade Science

 

      a. Compounds and Mixtures

      b. Quarter: 1

 

II. Unit #2: Compounds and Mixtures     Unit Length: 6 weeks

                                                            

      a. Unit Introduction: During this unit, students will discover that the basic elements can be chemically combined to form simple compounds and these substances have different properties than those of the elements from which they are made. That many different combinations of elements are possible, making a variety of substances. Additionally, students will discover that substances can be physically combined forming a mixture. Those mixtures of simple substances can be separated using the properties from which they are made. 

                                                                                                                                                                                                                                               

      b. Standards for Unit #:

CT State Grade Level Expectations (Draft)

GRADE-LEVEL CONCEPT  1:u Mixtures are made of combinations of elements and/or compounds, and they can be separated by using a variety of physical means.

GRADE-LEVEL EXPECTATIONS:

 

1.     Everything is made of matter.  Matter has two fundamental properties: it has weight (mass) and it takes up space (volume).

2.     All matter has a variety of properties, some of which are characteristic of the substance.  Characteristic properties do not depend on the amount of the substance (as mass and volume do).  Properties such as magnetic attraction, conductivity, density, pH, boiling point and solubility are characteristic properties that can be used to identify substances. 

3.     Solids, liquids or gases can be combined to form mixtures.  In a mixture, each substance keeps its individual properties.  In some mixtures, each of the components can be seen (for example, rocks, twigs, insects and leaves are visible components of soil); in other mixtures, the individual substances blend so well that they appear to be a single substance (for example, oxygen, nitrogen and carbon dioxide are mixed together to form air).

4.     Mixtures can be separated using different methods, depending on the physical properties of the component substances.  Filtering, evaporating, floating/settling, dissolving, and using magnets are all methods for separating mixtures based on the properties of their components. 

5.     Solutions are mixtures that appear to be single substances because particles have dissolved and spread evenly throughout the mixture.  Not all separation methods are effective for separating the components of solutions. 

GRADE-LEVEL CONCEPT 2: u Pure substances can be either elements or compounds, and they cannot be broken down by physical means.

GRADE-LEVEL EXPECTATIONS:

1.     All matter is made of particles called atoms that are too small to be seen without special magnification.  For example, a gold ring can be broken into smaller and smaller pieces until the pieces are no longer visible.

2.     All matter is made of different combinations of about 100 pure substances called elements.   The smallest particle of an element is an atom.  Iron is an example of an element that is made up of only iron atoms.

3.     Each element has distinct characteristic properties.  The Periodic Table of Elements is used to organize elements based on properties such as their reactivity, state of matter, conductivity or density.  Element names are represented by letter symbols on the Periodic Table.

4.     Some elements, such as iron (“Fe”) and aluminum (“Al”), are classified as metals because they have similar properties.  Individual metallic elements have distinct characteristic properties (for example, sodium (“Na”) is a light, soft metal that is nonmagnetic, while iron is a magnetic metal that is denser than sodium and aluminum).

5.     Some elements, such as carbon (“C”), hydrogen (“H”), oxygen (“O”) and chlorine (“Cl”), are classified as nonmetals.  Carbon is a nonmetal that occurs in several different forms (graphite, diamond, and coal), each of which has distinct properties.  Hydrogen and oxygen are nonmetals that are similar in that they are both gases; however, each gas has distinct characteristic properties.

6.     Atoms can combine chemically to make a molecule of a new substance with new properties called a compound. A molecule is the smallest part of a compound and is made of atoms of different elements in specific amounts.  Unlike mixtures, compounds cannot be separated using the physical properties of the component elements.

7.     Compounds have different properties than the individual elements of which they are made.  For example, table salt (NaCl) is a compound with different characteristic properties than the elements sodium and chlorine from which it is made; water (H20) is a compound with different characteristic properties than the elements hydrogen and oxygen from which it is made.  Different amounts of the same elements can produce compounds with different properties (for example, water (H20) and hydrogen peroxide (H202).

8.     In a chemical reaction, atoms can rearrange to form different molecules of new compounds. During photosynthesis, carbon dioxide (CO2) is taken in by green plants and combined with water (H2O). The carbon, hydrogen and oxygen atoms rearrange to make two new compounds: glucose (made of atoms of carbon, oxygen, and hydrogen) and oxygen gas (made of atoms of oxygen).

9.     In a chemical reaction, the same amount of matter (mass) is present at the start and the end, since the atoms are not created or destroyed but simply rearrange.

 

SCIENTIFIC LITERACY TERMINOLOGY:  Characteristic property, mass, weight, volume, density, solubility, boiling point, mixture, solution, particle, atom, element, molecule, compound, metal, non-metal, chemical reaction    

     

 

c. Essential Questions:

1. How do compounds chemically combine?

2. What is the difference between a physical and a chemical change?

3. How can compounds have different properties than the elements that make them up?

4. How can a mixture be separated by using physical properties?

 

 d. Essential Content/Concepts:

1.  A compound is a substance made of two or more elements that are chemically combined.

2.  A compound is represented by a chemical formula.

3.  The smallest part of a compound is a molecule.

3.  A substance that undergoes a physical change is still the same substance after the change.

4.  A chemical change produces new substances with properties different than those of the original substances.

5.  When elements are chemically combined, they form compounds, such as water and table salt that have properties that are different from the elements of which they are made.

6.  A mixture is made of two or more substances that are not chemically combined.

7.  Mixtures can be separated by physical properties such as particle size, density, solubility, and boiling point.

 

 

e. Essential Skills:

1.  Separate substances in a mixture.

2.  Compare and contrast the properties of water with those of hydrogen and oxygen.

3. Design and conduct appropriate types of scientific investigations to answer different questions.

4. Identify independent and dependent variables, and those variables that are kept constant, when designing an experiment

     

 

 

 f. Vocabulary –

Compound, mixture, chemical change, physical change, solubility, boiling point, substance, molecule, chemical formula, solid , liquid, gas, rate of reaction,

 

g. Science Misconceptions

1. A physical change produces new substances.

2. A chemical change does not produce a new substance.

                           

 

Activities

 

1. Labs:

  1. Rate of Dissolving
  2. Separating Sand, Salt, and Iron Inquiry Lesson
  3. Separating sand, Salt, Iron Lab
  4. NeoSci Elements, Mixtures and Compounds Lab

 

2. Reading for Information    

     a. A $3 Water Purifier That Could Save Lives

     b. Phosphate Mines

    

 

3. Web or Library Research

     a. “Compounds and Mixtures that Innovate” research compounds that have changed or advanced society. Examples are ceramics, plastics, Teflon, concrete, bronze, and steel

 

4. Multimedia Presentations

     a. Discovering the Elements Part II (57:12) United Streaming Videos

 

 

 

IV. Significant Tasks (ST)

Significant Task 2: Separation of a Mixture (Lab packet)

 

 

1.  Significant Task Introduction: The Separation of a Mixture Task will reinforce the experimental process. Using the “Lab Packet” students will identify and define variables for a scientific investigation. Write an appropriate procedure to solve the identified problem and conduct an investigation. Using suitable scientific tools the student will measure and use mathematical operations to calculate volume and density in metric units and record data, drawing conclusions and assessing their validity. Assessment: Lab Packet Rubric

 

 

      b. Length/Timing:  End of Unit 2

 

      c. Essential Questions:

          1. How are variables identified?

          2. Why should procedures be detailed?

          3. What information belongs in a data table?

       

      d. Assessment Tools (AT): Lab Packet

 

     

UNIT RESOURCES:

            Readings, Texts, Materials, Videos

 

 

Example Assessment Questions:

 

  1. Which of the following is a physical change?

a. the souring of milk  b. the burning of oil   c. the melting of ice  d. the rusting of iron

 

  1. Which process involves a chemical change?

a. dissolving sugar in water b. boiling water  c. freezing water  d. electrolysis of water

 

  1. In making an omelet, which process involves a chemical change?
  1. melting butter  b. chopping onions  c. frying eggs  d. adding salt

 

  1. A chemical change always

a. forms one or more substances    c. absorbs heat 

      b. releases heat                               d. absorbs electricity

 

  1. Describe what happens to a substance when it goes through a physical change.

 

 

 

 

  1. A statue on the New Haven Green was originally a copper color. After being exposed to the air, it turned a greenish color. What kind of change happened? Explain your answer