Read Grade 7 Chemistry Lesson.doc text version

Metals and Nonmetals

Teacher Notes

Grade: 7 Connections to Texas Essential Knowledge and Skills Knowledge and Skill Student Statement Expectation SCIENCE CONCEPTS 7.7 The student knows that substances have physical and chemical properties. The student is expected to: (B) describe physical properties of elements and identify how they are used to position an element on the periodic table.

SCIENTIFIC PROCESSES

7.1 The student uses scientific inquiry methods during field and laboratory investigations.

The student is expected to: (B) collect data by observing and measuring (C) organize, analyze, make inferences, and predict trends from direct and indirect evidence

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Formative Assessment Student progress and understanding is monitored throughout each activity by teacher observation, questioning, jour nal entries including drawing and writing samples, and recorded observations on data sheets. See Student Data Sheet on page 9.

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Summative Assessment Students will write descriptive comparisons to demonstrate their conceptual understanding of the physical properties of elements and how they are used to position them on the periodic table of elements. See Scoring Rubric on page 18.

Bridging to TAKS in Secondary Science Science Center for Professional Development in Curriculum & Assessment - 2001

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Metals and Nonmetals

Summary: (for teacher use only)

Teacher Notes

A patterning process will be repeated throughout this series of learning experiences to develop a general understanding of the significance of the position of elements on the periodic table. Emphasis for this grade level will be on the METAL - NONMETAL correlation to LEFT - RIGHT position on the table. Common compounds will be analyzed for metal and nonmetal composition, stressing the order of compound formation as METAL - NONMETAL, with the metal listed first. The correlation between elements and compounds is critical to conceptual understanding when students begin to study atomic structure in the 8 th grade and begin practice in writing formulas. This set of lessons attempts to create a strong set of inductive experiences that will create lasting understanding with models and examples that will continue to form a frame of reference in later years. At this age level, the focus is still on the macro level, reserving atomic structure and equations for later study. It is very tempting to start with the symbolic framework of the periodic table, studying electron dot diagrams, isotopes, and ionization assignments for columns, for instance, but this technical approach should come AFTER students become familiar with elements at the macro level. A careful review of the TEKS illustrates the scaffolding that occurs, through its progressive terminology and student skills across grade levels. This seventh grade level is a pivotal stage, and very difficult to stay focused on the macro level when using conventional textbook resources. However, the 7 th grade year provides a wonderful opportunity to explore the everyday uses for elements, incorporating environmental issues, conservation of resources, and relationships to geological topics.

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Metals and Nonmetals

Teacher Notes

Materials Lego® blocks or models formed from paper chart paper markers samples of elements: carbon, iron, copper, sulfur, aluminum, lead electrical conductivity kits magnets heavy duty plastic bags pliers Advance Preparation Construct enough models from Lego® blocks or paper for each small group of students to have one plus four extras for demonstrating an example and a nonexample. Form some of the models using combinations of blocks that are all of an IDENTICAL type (see examples below). Form some of the models using combinations of blocks that are different from each other (see non-examples below). 3 EXAMPLES 3 NON-EXAMPLES

blue blue

blue

yellow

blue

yellow

yellow yellow yellow yellow

green

green

green

green

green green green

blue green

green

blue green

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Metals and Nonmetals

Introduction § §

Teacher Notes

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Place a different model made of Lego® blocks or paper at each student group. Tell students that they will form a working definition of a concept by using the model structures. Show students two different structures: one that represents an EXAMPLE and one that represents a NON-EXAMPLE. (See Advance Preparation on previous page) Have students at each group discuss their model and decide if it is more like the EXAMPLE or the NON-EXAMPLE. Ask for volunteer group to bring their model forward and state whether it best represents an EXAMPLE or a NON-EXAMPLE. By a show of hands, ask the class to indicate if they agree or disagree with the volunteer group's decision. Without comment, place the model beside its matching structure (Example or Non-Example). Call for a volunteer group to submit a model that matches the Example group. Allow the class to indicate with a show of hands if they agree or disagree. Without comment, place the model with its matching structures. Continue the cycle until all models are used. In their small group, have students construct a definition for the "Example" models that would be clear enough to account for all the Examples and Nonexamples presented to this point. Have each group write a consensus definition on chart paper and post for the class to view. Bring out two new models and ask the class to vote on placement: Example or Non-Example. Place the models in the correct category. Ask the class to predict what the Example models might represent with respect to the topic of "Structures of Matter." Guide the group into selecting "ELEMENTS" as the correct answer, or if necessary, just tell them. Refer students back to the posted definitions. Ask which one most clearly defines an element. An element is a pure substance that is composed of the same type of matter throughout and cannot be divided into simpler substances through normal processes.

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NOTE: The instructional strategy described above is known as "concept attainment". It has wide use across multiple content areas. Students generally find the strategy to be very interactive and effective at creating a lasting image for later recall of the critical concept being represented.

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Metals and Nonmetals

Teacher Notes

Experience 1: Observe the physical properties of elements and classify them as metal or nonmetal § § Pass out a simplified, black and white copy of the Periodic Table of Elements. Introduce the table to students and explain that various combinations of elements represented on this table make up ALL the matter in our natural world. Explain that the Periodic Table of Elements is one of the most useful tools that scientists have and that they will study about the table during the next few years of science. In small groups, have students observe and record physical properties of the sample elements. See Student Date Sheet on page 9 . Formative Assessment As a class, work through the first two listed elements as you engage students in the following discussion: Find carbon on your chart and record answers as we observe the physical properties of this element together. ð What should we write in the box to describe the color of carbon? (black) ð The chart states that luster means the way something reflects light. What should we write in the box to describe the luster of carbon? (dull) ð To test the brittleness of carbon, use the pliers to nip one small part of the sample. Did it break easily or not at all? (breaks easily) What should we write in the box to describe the brittleness of carbon? (very brittle; breaks easily) ð Use your magnet to test if carbon is attracted by it. What should we record in the box to describe the magnetic attraction of carbon? (none) ð The chart states that malleable elements can be hammered into thin sheets. What should we record in the box to describe the malleability of carbon? (not malleable) ð Use your electrical conductivity kit to test if carbon allows electricity to move through it. Monitor groups and assist those who need help to build a simple circuit with the materials provided. ð What should we record in the box to describe carbon as a conductor of electricity? (does not conduct electricity) Formative Assessment Find iron on your chart and record answers as we observe the physical properties of this element together. ð What should we write in the box to describe the color of iron? (silverygray) ð The chart states that luster means the way something reflects light. What should we write in the box to describe the luster of iron? (shiny)

Bridging to TAKS in Secondary Science Science Center for Professional Development in Curriculum & Assessment - 2001

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Metals and Nonmetals

Teacher Notes

ð What should we write in the box to describe the brittleness of iron? (not brittle) ð What should we record in the box to describe the magnetic attraction of carbon? (strong magnetic attraction) ð What should we record in the box to describe the malleability of iron? (malleable) ð What should we record in the box to describe iron as a conductor of electricity? (good conductor of electricity) ð Based on your data, in what ways are carbon and iron alike? (both are elements) ð In what ways are they different? (based on observations recorded in the chart, these two elements have properties opposite of each other) § § Have the groups complete the chart for the remaining element samples and answer the questions. Engage the students in the following discussion: ð Read and discuss in your group the two definitions shown on the transparency slide. See Transparency Mastery on page 10. Formative Assessment Compare the two definitions to the two categories you used on your chart: "more like carbon" or "more like iron." ð Would you classify carbon as a metal or a nonmetal? (nonmetal) Why? (it has properties most like those described in the nonmetal definition) ð Would you classify iron as a metal or a nonmetal? (metal) Why? (has properties most like those described in the metal definition) Formative Assessment On your Periodic Table of Elements, color in the key using different colors to represent metals and nonmetals. Based upon your recorded observations, fill in the blocks on the periodic table of the 6 elements you tested using the appropriate colors. (metals: iron, lead, copper and aluminum; nonmetals: carbon and sulfur) ð Do you notice any pattern about the locations of the metals and nonmetals on your table? (metals on left, nonmetals on right; metals left of zigzag line, nonmetals right of zigzag line) ð Do you believe these positions are a coincidence or a real pattern? (acknowledge all answers; lead students to realize that metals really are on left and nonmetals on right)

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Bridging to TAKS in Secondary Science Science Center for Professional Development in Curriculum & Assessment - 2001

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Metals and Nonmetals

Teacher Notes

Experience 2: Use data to classify elements as metal or nonmetal and predict location on the Periodic Table of Elements § Without referring to the Periodic Table of Elements, have students work in small groups to test their understanding of metals and nonmetals by sorting description cards of elements into the two groups (metals and nonmetals). See Element Cards on pages 11-15. After groups have sorted the cards, have students match the elements to their position on the Periodic Table of Elements to see how they cluster (left or right). Formative Assessment As groups are working, monitor and check for understanding. See Teacher Notes for Sorting of Elements on page 16.

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Experience 3: Apply knowledge to new examples of metals and nonmetals and their position on the Periodic Table of Elements § § § Have students locate K and Cl on the Periodic Table of Elements and locate the Element Cards that surround the position of these two on the table of elements. Instruct students to discuss and record the properties of potassium and chlorine based on the cards of the surrounding elements. Facilitate a full group discussion on the accuracy of their predictions using the transparencies for potassium and chlorine. See Transparency Master on page 17. Summative Assessment Have students write a descriptive comparison of metals and nonmetals, based upon the physical properties of the elements, and identify how they are positioned on the periodic table. See Scoring Rubric on page 18.

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Metals and Nonmetals

PROPERTY

Student Data Sheet Sulfur Copper Aluminum

DESCRIPTION

Carbon

Iron

Lead

C

Fe

Pb

S

Cu

Al

COLOR

based on appearance

LUSTER

way it reflects light; shiny or dull

BRITTLENESS

how easily it breaks

MAGNETISM

whether or not it is naturally attracted by magnets

MALLEABILITY

how well it can be hammered into thin sheets

ELECTRICAL CONDUCTOR

how well it allows electricity to move through MORE LIKE CARBON MORE LIKE IRON

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Bridging to TAKS in Secondary Science Science Center for Professional Development in Curriculum & Assessment - 2001

Metals and Nonmetals

Transparency Master

METALS are usually. . . · silver-gray in color · solids at room temperature METALS . . . · reflect light when polished · can be bent or hammered flat (malleable) · generally have high melting points · are good conductors of heat and electricity NONMETALS . . . · exist as solids, liquids, or gases at room temperature · do not reflect light well · are usually brittle, cannot be hammered flat or rolled into sheets · generally have low melting points · are poor conductors of heat and electricity

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Metals and Nonmetals

Element Cards

Hydrogen (H) · Colorless · Gas · Melting Point = -259.14 oC · Poor conductor of heat and electricity · Used in balloons, metal refining

Helium (He) · Colorless · Gas · Melting Point = -272.0 oC · Poor conductor of heat and electricity · Used in balloons, deep sea diving

Lithium (Li) · Silvery, somewhat lustrous · Soft solid · Melting Point = 180.54 oC · Good conductor of heat and electricity · Malleable · Reacts strongly with water · Used in batteries, ceramics, lubricants

Fluorine (F) · Greenish · Gas · Melting Point = -219.62 oC · Poor conductor of heat and electricity · Used in refrigerants

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Metals and Nonmetals

Element Cards

Nitrogen (N) · Colorless · Gas · Melting Point = -209.9 oC · Poor conductor of heat and electricity · Forms most of atmosphere

Oxygen (O) · Colorless · Gas · Melting Point = -2184 oC · Poor conductor of heat and electricity · Supports life, supports burning

Sodium (Na) · Silvery · Soft solid · Melting Point = 97.8 oC · Good conductor of heat and electricity · Actively reacts with water · Used in medicine, agriculture

Magnesium (Mg) · Greyish · Solid · Melting Point = 650.0 oC · Good conductor of heat and electricity · Malleable · Used in airplanes, missiles

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Metals and Nonmetals

Element Cards

Phosphorus (P) · White (can be yellow) · Dull · Solid · Melting Point = 44.1 oC · Poor conductor of heat and electricity · Brittle · Used in fertilizers, detergents

Silicon (Si) · Grey · Solid · Melting Point = 1410.0 oC · Conducts electricity under some conditions · Used in glass, semiconductors

Bromine (Br) · Reddish brown · Liquid · Melting Point = -7.2 oC · Poor conductor of heat and electricity · Poisonous; used in fire retardents, water treatment

Argon (Ar) · Colorless · Gas · Melting Point = -189.3 oC · Glow in high electrical voltage · Used in lighting

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Metals and Nonmetals

Element Cards

Cesium (Cs) · Silver · Soft solid · Melting Point = 28.5 oC · Good conductor of heat and electricity · Explodes violently in water · Used to remove air traces in vacuum tubes

Calcium (Ca) · Silvery · Solid · Melting Point = 839.0 oC · Good conductor of heat and electricity · Malleable · Highly reactive with other elements · Used by life forms for bones and shells Cobalt (Co) · Greyish tinge, lustrous · Solid · Melting Point = 1495.0 0C · Brittle · Naturally magnetic · Conducts heat and electricity · Used in magnets, ceramics, special types of glass

Arsenic (As) · Grey · Solid · Melting Point = 817.0 oC · Conducts electricity under certain conditions · Used in poison, semiconductors

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Metals and Nonmetals

Element Cards

Barium (Ba) · Silver · Solid · Melting Point = 725.05 oC · Good conductor of heat and electricity · Malleable · Used in medical applications, ceramics, polypropylene · Nickel (Ni) · Silvery tinge, lustrous · Solid · Melting Point = 1453.0 0C · Conducts heat and electricity · Naturally magnetic · Malleable · Used in coinage, stainless steel, electroplating, batteries

Rubidium (Rb) · Silver · Solid · Melting Point = 38.89 oC · Conducts heat and electricity · Reacts violently with water · Used as catalyst, in photocells

Krypton (Kr) · Colorless · Gas · Melting Point = -157.2 0C · Poor conductor of heat and electricity · Used in lighting

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Metals and Nonmetals

Teacher Notes

Sorting of Elements (for teacher use only) The packet of element description cards was prepared from several references, so there is some variance in amount and types of characteristics listed for each. There is sufficient detail for each element to accomplish this task, without giving too much information to sort. As you observe the small groups working, you will probably see that they will sort the elements into three or four piles on the first attempt. It is important that they don't use the periodic table as a reference during this activity, to keep the focus on the descriptive qualities. The likely sorting (and answers to sorting questions) will fall into these categories: 1. Clearly metal -- silver-colored solids that conduct electricity 2. Clearly nonmetal -- gas, not silvery, poor conductors, and very low melting points 3. Uncertain -- different color, conduction, luster, or just not enough information The terms "transition" and "metalloid" should be introduced in the de-briefing of this activity to illustrate to students that the characteristics of metals and nonmetals are not clearly defined for all elements. Also, HYDROGEN should be pointed out as an exception to the general guidelines fo r placement on the periodic table at this time. It's placement will be studied further in the future. Some transition metals were included in this packet to provide descriptions for elements seen in class samples (iron and copper) and to show the only three elements that are naturally magnetic (iron, cobalt, and nickel)--located together in the midst of the transition metals. When the cards are arranged in the order of the periodic table at the end of this activity, the metalloids and transition elements will be apparent. Students should develop their understanding of the metal - nonmetal pattern as: · · · Metals - left side of the table, including transition elements Nonmetals - upper right corner area and far right column Metalloids - in a diagonal line sta rting with Boron, moving down and right

At this point, students will have questions about a "clear definition" of a metal. They should know that, as their understanding and knowledge of the structure of elements grows, they will learn more ways that scientists classify the elements, defining a metal based on more than its physical properties that can be observed at this time.

Bridging to TAKS in Secondary Science Science Center for Professional Development in Curriculum & Assessment - 2001

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Metals and Nonmetals

Transparency Master

Potassium · Silvery · Solid · Soft (can be cut with knife) · Melting Point = 63.650C · Good conductor of electricity · Highly reactive in water · Used in glass, soap Chlorine · Green · Gas 0 · Melting Point = -100.98 C · Poor conductor of electricity · Used in water purification, bleaches

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Metals and Nonmetals

Scoring Rubric

SUMMATIVE ASSESSMENT Define "element" and explain how the LEGO structures that we used modeled an element. Use your knowledge of metals and nonmetals to describe and predict typical physical properties of elements by how they are positioned on the periodic table. (Consider the left and right sides of the table as well as the upper and lower portions, for the elements studied in this unit.) The following rubric will be used to assess your answers.

Physical Properties of Elements Metals and Nonmetals (M/NM) Periodic Table Arrangement

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Define an element in clear, concise terms, matching LEGO properties to element properties. Describe 4 or more identifying physical properties for elements

Describe 4 or more characteristics for M/NM, with examples, including exceptions, and relate to everyday uses

Identify how the elements are positioned on the periodic table, using examples, diagrams, or o ther clarifying descriptors

3 2 1

Define an element, including 3-4 identifying properties for elements

Describe 4 or more characteristics for M/NM, with examples, and discuss exceptions

Identify how the elements are positioned on the periodic table, as experienced in class

Define an element and 23 identifying properties for any element

Describe 3-4 Describe 2 or more uses characteristics for M/NM, for the periodic table, with several examples including metal nonmetal.

State the definition of an element

Describe two or less Describe the general characteristics for M/NM, purpose for the periodic with examples table, known at this time

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