Introduction Unit Framework Title Exploring Change

Title: Exploring Change Subject: Chemistry Topics: Atomic structure, bonding, properties of matter, conservation of matter, chemical

formulas, stoichiometry, acids and bases Grade: High School Designers: Laura Kornagay, Bobby Timms, Miriam Jordan, Cheryl Thomasson

Georgia Department of Education Kathy Cox, State Superintendent of Schools

GeorgiaStandards.Org

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Introduction Unit Framework Title Exploring Change Unit Framework Annotation This unit is designed to build the enduring understanding that atomic structure dictates bonding, which in turn determines the structure of molecular and ionic compounds, diatomic elements, and allotropes, and that these structures determine the compounds’ properties. The unit builds on bonding and conservation of mass to begin the study of patterns of reactions, balancing chemical equations and stoichiometric calculations related to the reactions. Both manipulatives and traditional lab activities are integral parts of the exploration in this unit. This unit integrates the understandings from “Finding Order” and “Finding Patterns” to explore how atoms and ions bond and the changes that occur when bonds are broken or formed.

• IUPAC conventions for writing formulas and naming compounds are taught. • The mole concept is extended to compounds and balanced equations in this unit. • Stoichiometry is introduced and used to make calculations consistent with the conservation of matter. • Acids and bases are explored as specific categories of compounds.

The instruction, tasks, and assessments in this unit are suggested but should be adjusted, omitted, or enhanced as needed for specific class situations. Some classes may need more time, practice, or instruction for some concepts. Others may need less. Fore these reasons, the number of days required may need adjustment.

Approximate Duration for the Unit Framework 5 weeks-variable (Depending on the needs of the students, the actual time needed for practice, informal assessment, and adjusting instruction may be more than 5 weeks.) Authors Laura Kornagay, Bobby Timms, Miriam Jordan, Cheryl Thomasson Email Address

Standards Focus Content Standards SC1. Students will analyze the nature of matter and its classifications. SC1b. Identify substances based on chemical and physical properties. SC1c. Predict formulas for stable ionic compounds (binary and tertiary) based on balance of charges. SC1d. Use IUPAC nomenclature for both chemical names and formulas: • Ionic compounds (Binary and tertiary) • Covalent compounds (Binary and tertiary) • Acidic compounds (Binary and tertiary) SC2. Students will relate how the Law of Conservation of Matter is used to determine chemical



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composition in compounds and chemical reactions. SC2a Identify and balance the following types of chemical equations: • Synthesis • Decomposition • Single Replacement • Double Replacement • Combustion SC2b. Experimentally determine indicators of a chemical reaction: specifically precipitation, gas evolution, water production, and changes in energy to the system. SC2c. Apply concepts of the mole and Avogadro’s number to conceptualize and calculate •Empirical/molecular formulas, •Mass, moles and molecules relationships SC2d. Identify and solve different types of stoichiometry problems, specifically relating mass to moles and mass to mass. SC3. Students will use the modern atomic theory to explain the characteristics of atoms. SC3e. Compare and contrast types of chemical bonds (i.e. ionic, covalent). SC7. Students will characterize the properties that describe solutions and the nature of acids and bases. SC7b. Compare, contrast, and evaluate the nature of acids and bases: Integrated Characteristics of Science Standards SCSh1a Exhibit curiosity, honesty, openness, and skepticism in their own scientific activities. SCSh2. Students will use standard safety practices for all classroom laboratory and field investigations. SCSh3. Students will identify and investigate problems scientifically. SCSh4. Students will use tools and instruments for observing, measuring, and manipulating SCSh5. Students will demonstrate the computation and estimation skills necessary for analyzing data and developing reasonable scientific explanations. SCSh6a. Write clear, coherent laboratory reports related to scientific investigations. SCSh6b. Write clear, coherent accounts of current scientific issues, including possible alternative interpretations of the data. SCSh8b. Scientific researchers are expected to critically assess the quality of data including possible sources of bias in their investigations’ hypotheses, observations, data analyses, and interpretations. SCSh8e. The ultimate goal of science is to develop an understanding of the natural universe which is free of biases. SCSh8f Science disciplines and traditions differ from one another in what is studied, techniques used, and outcomes sought. Complementary Standards SC1b. Identify substances based on chemical and physical properties SC5. Students will understand the rate at which a chemical reaction occurs can be affected by changing concentration, temperature, or pressure and the addition of a catalyst



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Understanding and Goals

Unit Understandings, Themes, and Concepts determines • A chemical bond is a force holding atoms/ions in a combined state. • The bond may be ionic or covalent, or may be categorized along a continuum between ionic and

covalent. • Atomic structure dictates bonding, which in turn determines the structures of compounds (and

diatomic molecules of elements), and structures determine the compounds’ properties. • In a chemical change, bonds are broken and new bonds are formed, matter is conserved, and energy

is always involved. • Indicators of chemical change include color change, formation of a precipitate or water, evolution of

a gas, and changes in energy. (See teacher note below.)* • Most reactions can be described by five basic patterns of reactions. • Chemical formulas reflect the conservation of matter in bonding and can be determined

experimentally. *Teacher Note: The same indicators may be observed in numerous physical changes. However, the important difference here is that the color change, the odor produced, the precipitate formed, or the gas evolved, results because a new product was formed in the reaction; whereas these indicators in a physical change result because the same substance is in a different state or condition. Point out this crucial difference throughout this unit. An example of this would be that when silver nitrate and sodium chloride react, the products are silver chloride ( a white precipitate), and sodium nitrate. The new precipitate indicates a chemical reaction. When sand and water are mixed and agitated, the sand is suspended in the water. Over time the sand settles (precipitates to the bottom) but it is still sand. This is a physical event. Students should understand that energy is involved in both physical and chemical changes. Essential Questions What determines how elements are attracted to each other in compounds? How do elements bond? (What is a chemical bond, anyway?)

How are properties related to bonding? How are formulas written to reflect the composition of compounds? How are ionic and molecular compounds named? How do groups of atoms form polyatomic ions and why do they act as a single unit when bonding with other ions?

How can you tell if a chemical change has taken place? What are indications that chemical reactions have taken place?

How are formulas determined experimentally? What do glucose, acetic acid, and formaldehyde have in common? (How can you determine if the molecular formula is a multiple of the empirical formula?)

Where do acids and bases fit into the organization of compounds? How are formulas for acids and bases written and how are they named?

Balanced Assessments



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Method types

Informal Observations

Dialogue and Discussion

Selected Responses

Constructed Responses

Self-Assessments

Monitor progress during formula writing practice Monitor practice during mole conversions

Student/teacher Peer conferencing Whole group discussion Discuss bonding; monitor student understanding through questioning Discussion during acid/base lab—check for understanding Discuss physical and chemical properties; monitor student understanding through questioning

Teacher prepared items on quizzes and summative test to assess specific unit content

Writing: How is salt different from sugar? Graphic organizer: properties of acids & bases Formula construction Ionic/covalent properties Indications of chemical reaction lab Formula of a hydrate lab Quizzes on formula writing /naming, empirical/ molecular formulas Formula—mole conversions Empirical formula of magnesium oxide calculation Balance equations identify reactions

Analysis of reactions task

Practicing mole conversions Practicing writing formulas Practice balancing equations

Unit Performance Task(s) Unit Performance Task Titles Task 1: “Water” You Thinking? Task 2: Reaction Types Concept Map Performance TaskTask 3: Analysis of Reactions ( from bag reactions) Description/Directions: Task 1- “Water” You Thinking: Student writes an analytical essay to explain how atoms and ions bond. The title alludes to the uniqueness of the bonding in and between water molecules and should prompt the students to consider the range of possibilities that exist in bonding.



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Task 2: Students summarize the understandings of this unit on a concept map of reaction types. Task 3: Students prepare an analysis of all the reactions that occur in the “Bag Reactions” task. Follow the links given above or go to the appendix of this unit for details and description. Rubric for Performance Task Reaction Types Concept Map

Student Work Sample with Teacher Commentary

Sequence of Instruction and Learning

Teacher Activities Model how the octet rule applies to ionic and covalent bonds. Discuss bonding: have students brainstorm what they already know about bonding; use this activity to lead into discussion. Model the balance of charge with ion manipulatives and demonstrate how formulas are determined. Model and discuss polyatomic ions. Explain and model IUPAC nomenclature. Demonstration: burn magnesium to form magnesium oxide; discuss the energy involved. Provide safety instruction and enforcement. Monitor and assess group work. Orchestrate lesson on dihydrogen monoxide. Review what was learned from the properties of acids & bases lab—discuss in further detail. Model the stoichiometry for determining empirical formula from experimental data. Discuss the difference in empirical and molecular formulas.

Student Activities Valence graphic organizer Octet game-crazy eights Formula construction task Polyatomic Ion Bee Practice formula writing and compound naming Graphic organizer: properties of ionic and covalent compounds Ionic/covalent properties lab Calculate the ionic character of a compound Discrepant event with water Indicators of chemical change lab Properties of acids & bases lab

Empirical formula lab (MgO) Calculate empirical formula from data Determine molecular formula from data



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Discuss hydrate compounds. Demonstrate reactions that provide obvious examples of the evidence of chemical change. Demonstrate, discuss and model the balanced equations for examples of the five types of reactions Provide instruction and guided practice for balancing equations and working stoichiometry problems.

Formula of a hydrate lab Recognize reaction types, predict products and balance equations

Sequence of Activities, Tasks, and Assessments for Unit Teacher Note: Tasks in the unit are linked to their descriptions in the appendix. Throughout this unit, students will have laboratory experiences. Lab activities always require strict adherence to lab safety. Train students in safety and review before each lab experience. Safety reminders ( ) are included but do not take the place of a school’s comprehensive safety plan which must be maintained and enforced in the laboratory and classroom.

Day

1

EQ: What determines the ways that elements are attracted to each other? How do elements bond to form compounds? Understandings: • A chemical bond is a force holding atoms/ions in a combined state. • The bond may be ionic or covalent, or may be categorized along a continuum between

ionic and covalent. • Atomic structure dictates bonding, which in turn determines the structures of

compounds (and diatomic elements and allotropes), and structures determine the compounds’ properties.

• In a chemical change, bonds are broken and new bonds are formed. Energy is always involved.

Activate this lesson by having students review the valence electrons of the

representative elements on the periodic table and complete the graphic organizer. Introduce (or review) the octet rule. Model examples of how this applies to ionic and

covalent compounds. Use transparencies or a computer simulation to illustrate the difference in an atom and an ion of the same element, the transfer of electrons, and the sharing of electrons.

Examples of internet resources are: Octet rule exceptions and examples and http://ithacasciencezone.com/chemzone/lessons/03bonding/dogbonds.htm Play the Octet game to practice the concept of the octet rule.

Summarize by having students total their points and clear up any questions about the correctness of their “melded” compounds.

Day EQ: What determines the ways that elements are attracted to each other?

http://www.800mainstreet.com/4/0004-005-ion-octet.html

http://ithacasciencezone.com/chemzone/lessons/03bonding/dogbonds.htm



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2 • What is a chemical bond, anyway? • How are ionic and molecular compounds named? Understandings: •In a chemical change, bonds are broken and new bonds are formed, matter is conserved, and energy is always involved. •Indicators of chemical change include color change, formation of a precipitate or water, evolution of a gas, and changes in energy. (See teacher note related to this element at end of the Unit themes, understandings and concepts).*

Activate this lesson with a simple demonstration of a compound forming where the energy

change is dramatic. Burn a strip of magnesium ribbon, making sure that the students observe the strip of magnesium before the reaction and the white powder after the reaction. Make sure students realize that oxygen from the air is the second reactant.

Teacher note: Observe strict fire safety. Clean the magnesium ribbon with steel wool prior to the demonstration for best results and do not allow students to observe the white flame directly. Shield the actual flame from direct view. Elicit responses from the class about what they think is happening. Clarify as needed. Write the formula, for the product, MgO, on the board. The equation for the reaction can be given and discussed as a preview to the study of reactions. 2Mg + O2-- 2MgO Discuss conceptually the net exothermic nature of the reaction. Point out that energy is

required to change magnesium atoms into magnesium ions, and to change molecules of oxygen to separate atoms of oxygen. However, a greater amount of energy is released as the electrons from magnesium are gained by the oxygen atoms to form the stable compound, magnesium oxide. The ionic bonds in the compound are the force of attraction between the ions of opposite charge.

Introduce the IUPAC conventions for naming binary ionic compounds and continue the lesson with the use of models. See for the formula model construction activity. Commercial versions of this activity are available or they can be made. This activity allows students to understand that when ions combine, the charges have to “balance”

for them to form a compound. It also leads directly to formula writing. Go over the transition metals that have more than one common charge and relate this to their

electron structure, and the filling inner orbitals. Have students practice writing formulas and names for compounds that contain these transition metals.

Summarize lesson with a formative assessment giving students a new group of

compounds for which they must write the formulas. Check these quizzes before the class meets again in order to adjust or re-teach as needed before assigning a summative assessment.

Resources: Predicting formulas for ionic compounds Naming ionic compounds

Day

3 EQ: How do groups of atoms form polyatomic ions and why do they act as a single unit when bonding with other ions? Understandings:

http://www.800mainstreet.com/4/0004-0010-formula-ionic.html

http://www.800mainstreet.com/4/0004-0011-naming-ionic.html



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•A chemical bond is a force holding atoms/ions in a combined state. •The bond may be ionic or covalent, or may be categorized along a continuum between

ionic and covalent. •Atomic structure dictates bonding, which in turn determines the structure of

compounds (and diatomic elements and allotropes), and structures determine the compounds’ properties. Introduce some familiar tertiary ionic compounds: baking soda, Epsom salt, chalk, etc.

Write their formulas on the board, explaining how the polyatomic ion is bonded in the compound. Explain that the atoms within the polyatomic ion are bonded covalently to each other, but that overall they have (or lack) at least one extra electron, and act as a single unit in the role of a negative or positive ion in the compound.

Instruct students in the IUPAC conventions for writing these formulas and naming these compounds. Students practice writing formulas and naming tertiary compounds.

Homework (can be differentiated): Assign the making of flashcards for the polyatomic ions that students will be required to remember, or use frequently.

Ticket-out-the-door: Write formulas for one binary compound, one compound containing one polyatomic ion, and one formula for a compound that contains two different polyatomic ions.

Resource: Polyatomic

Day

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EQ: Why is salt different from sugar? (How are properties related to bonding?) Understanding: Atomic structure dictates bonding, which in turn determines the structure of compounds (and diatomic elements and allotropes) and structures determine the compounds’ properties.

Activation activity: Polyatomic ion formula bee. Self-assessment or formative assessment on formula writing. Resource: Polyatomic ions Performance task -Properties of compounds Prelab: Preface this lab with safety instruction and a mini-lesson on any equipment,

techniques, or procedures that students will need. Post lab: Students complete a lab report.

Teacher note: Resource for ionic compound properties: Atoms and subatomic particles

http://www.800mainstreet.com/4/0004-009-Polyatomicions.html

http://www.800mainstreet.com/4/0004-004-Properties.html



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Day 5

EQ: Why is salt different from sugar? (How are properties related to bonding?) Understanding: Atomic structure dictates bonding, which in turn determines the structure of compounds (and molecules of elements), and structures determine the compounds’ properties.

Activate this lesson by having students recall the properties of ionic and covalent compounds and discuss. Then students create their own graphic organizer to summarize this information.

Ask “What causes the differences? Entertain any observations made by the class. Review (from day 1) the nature of the covalent bond. Compare the force of attraction

found between ions in ionic compounds with the attraction for shared electrons in covalent compounds to guide the discussion about the differences in the general properties of ionic and covalent compounds.

Introduce the table of electronegativities and model the use of this table to predict the character of the bonds in a compound. If not already covered in the discussion of covalent bonding, explain the bonding of the seven diatomic elements. ( hydrogen, nitrogen, oxygen, fluorine, chlorine, bromine, and iodine).

Students practice using the table and predicting whether a given bond is ionic, polar covalent, or pure covalent.

Summarizing task: For the compounds used in the Properties of Compounds Lab, calculate their degree of ionic character and rank them from most ionic to pure covalent. Write a summarizing paragraph relating this new information to the properties that were observed in the lab.

Day 6

EQ: What makes dihydrogen monoxide so unique? Understanding: Atomic structure dictates bonding, which in turn determines the structure of compounds, (and diatomic elements and allotropes), and structures determine the compounds’ properties.

Activate this lesson by reporting to the class some “astounding” properties of dihydrogen monoxide (also known as hydrogen hydroxide):

• Is present in cases of excessive sweating and vomiting • A major component of acid rain • Can cause severe burns in the gaseous state • Accidental inhalation can kill you • Primary contributor to erosion • Decreases effectiveness of automobile brakes • Is associated with major cyclonic events • May dissolve metal ions especially in the presence of road salt • Reacts violently with certain metals, such as sodium and potassium

Ask students if they have ever come in contact with this compound. If the students have not already realized that the compound in question is water, ask them to write the formula for it using the rules they have learned.

Once the identity of the compound is understood, ask students to list the beneficial functions of water. List these on the board.



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Using this list, discuss the unique properties of water and how these properties are related to the functions of water. Discuss the polar covalent bonding and hydrogen bonding and how these relate to capillarity, temperature regulation in the body and in the environment, and water’s ability as a solvent.

Students carry out the discrepant event with water to reinforce and summarize the properties of water.

To extend and differentiate this lesson, as time allows, or to consider for a project near the end of the year, the Dihydrogen Monoxide Environmental Issue Project can be done.

Teacher Note: See http://www.dhmo.org/ for more on this project. StudentsDihydrogen Monoxide Environmental Issue Project really get into this lesson on the importance of nonbiased data!

Day 7

EQ: How are ionic and molecular compounds named? Understanding: Science disciplines and traditions differ from one another in what is studied, techniques used, and outcomes sought.

Activate this lesson by reviewing how ionic compounds are named. Review the rules for naming a compound containing a metal that can have more than one common charge.

Provide more practice as needed. Introduce the IUPAC nomenclature for covalent compounds. (Remind students that

water is a notable exception.) Model the naming process. Students practice. Monitor, adjust, re-teach, differentiate. Ticket-out-the-door: Give students a mix of formulas for ionic and covalent compounds

for which the students will write the names. Also assign the names of some compounds for which the students will write the formulas.

Teacher note: Most texts provide flowcharts that are good graphic organizers for naming and formula writing. These can also be found on the internet.

Day 8,9

EQ: Where do acids and bases fit into the organization of compounds? How are formulas for acids and bases written and how are they named? Understanding: Atomic structure dictates bonding, which in turn determines the structure of compounds (and molecules of elements), and structures determine the compounds’ properties.

Introduce the ionic nature of acids and bases. Ask students to refer to their data from the properties of compounds lab. Were the NaOH and the HCl solutions conductors or nonconductors? What does that indicate about the kind of compounds they are?

Discuss the traditional definition of acid and base, emphasizing the role of the dissociated ions in solution. (Review the basics of solutions if needed.)

Demonstrate the physical and chemical properties of acids and bases. Students record their observations on a graphic organizer or VENN diagram to

summarize these properties. Students conduct an exploratory lab on properties of acids and bases. Test a series of

aqueous solutions using litmus, or other indicators; check conductivity; mix equal volumes, 10 mL, of 0.l M HCl with 0.1 NaOH. Test the resulting solution with the

http://www.dhmo.org/



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indicator(s). Resource: Most lab books have a version of this lab. Teacher note: Acids, bases, pH, etc. will be covered in greater depth in a subsequent

unit, but are introduced here in the context of bonding, properties and formulas.

Teacher note on safety: Review and require students to follow all appropriate lab safety rules, including the wearing of goggles and aprons, clothing safety and the handling of corrosive chemicals. Students must be thoroughly knowledgeable about the use of safety equipment including the shower, eyewash, sinks, and fire extinguisher.

Day

10

EQ: How are formulas for acids and bases written and how are they named? Understanding: Atomic structure dictates bonding, which in turn determines the structures of compounds (and diatomic elements and allotropes), and structures determine the compounds’ properties.

Activate this lesson by having students summarize what they learned about acids and based in the lab. (Informal assessment)

Clarify and re-teach as needed. Explain how acid formulas are written and how they are named. Connect the tertiary

acids back to their corresponding polyatomic ions. Model the use of a flowchart for naming acids and bases. (found in most texts or on-

line). Students practice this skill; teacher monitors, facilitates, adjusts, and re-teaches. Students summarize by writing the formulas and names for three binary acids,

Two tertiary acids, and one base.

Day 11, 12 Time needed to teach this lesson will vary based on the needs of the class.

EQ: How are empirical formulas determined experimentally? Understanding: Chemical formulas reflect the conservation of matter in bonding and can be determined experimentally.

Activate lesson with a review of the mole concepts (see unit, Finding Order). Model the calculation of gram formula mass. Review and practice dimensional analysis.

Students practice. Monitor, assist, adjust, re-teach as needed. Lab: Students will experimentally determine the empirical formula of a compound. A

suggested lab that is found in many chemistry resources is the determination of the empirical formula of magnesium oxide. Students carry out the lab. Based on the mass of the original magnesium and the mass of the product, magnesium oxide, students will determine the empirical formula for this compound.

Teacher note on safety: Review and require students to follow all appropriate lab

safety rules, including the wearing of goggles and aprons, clothing safety, procedures for handling chemicals, fire safety, and lab burner safety. Students must be thoroughly knowledgeable about the use of safety equipment including the shower, eyewash, sinks, and fire extinguisher.

Model the stoichiometry for determining the empirical formula from the mass data



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obtained in the lab. The students calculate their own data. Collect data from all groups on a master data

table for the class to analyze. Model stoichiometry for percent composition problems. Graphic organizers for working

the problems will be useful. Students practice a variety of examples. (There may me a need for differentiating the

problems as students progress in their understanding.) Students turn in their percent composition problems for formative assessment.

Day

13

EQ: What do glucose, acetic acid, and formaldehyde have in common? (How can you determine if the molecular formula is a multiple of the empirical formula?) Understandings:

• Chemical formulas reflect the conservation of matter in bonding and can be determined experimentally.

• Atomic structure dictates bonding, which in turn determines the structures of compounds (and diatomic elements and allotropes), and structure determines a compound’s properties.

Activate lesson with by asking students to list what they know about these three

compounds. Then inform the class that all three have the same empirical formula, CH2O.

Build on the understandings developed thus far in this unit to discuss the importance of recognizing that properties are tied to structure, and that the true molecular formula can be a multiple of the empirical formula.

Teach the stoichiometry for determining molecular formula. Students practice. Monitor, assist, adjust, re-teach as needed. Students turn in work for formative assessment. Homework Practice and study for quiz on determining formulas from empirical data.

Day 14

Give quiz on formula writing and naming and calculating empirical formulas and

molecular formulas. Assign the performance task, “Water” you thinking? Introduce this task by reviewing the

nature of water and the way its atoms are bonded in the molecule and how the water molecule is attracted to other molecules. Explain that the title draws on this understanding about water. See task details in appendix. Students will work on this task after the quiz.

Day 15

EQ: How are formulas written to reflect the composition of compounds?

Understanding: Chemical formulas reflect the conservation of matter in bonding and can be determined experimentally.

Activate this lesson by using copper(II) sulfate pentahydrate to demonstrate what happens when hydrates are heated. Show what happens when water is added to the anhydrous form. Discuss how hydrate formulas are written and how they are named.

Lab: Empirical formula of a hydrate (A version of this lab is found in many lab books.)



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Teacher note on safety: Review and require students to follow all appropriate lab safety rules, including the wearing of goggles and aprons, clothing safety, procedures for handling chemicals, fire safety, and lab burner safety. Students must be thoroughly knowledgeable about the use of safety equipment including the shower, eyewash, sinks, and fire extinguisher.

Day 16

Use this day for students to review, get help, or complete labs, in preparation for a summative assessment over bonding, compounds (naming and writing formulas), and acids and bases.

Day 17

Summative assessment on bonding and formulas; “Water” You Thinking Task is due.

Day 18

EQ: How can you tell if a chemical change has occurred? Student writes an analytical essay to explain how atoms and ions bond. The title alludes to the uniqueness of the bonding in and between water molecules and should prompt the students to consider the range of possibilities that exist in bonding.

l if a chemical change has taken place?

What are indications that chemical reactions have taken place? Understandings:

• Matter is neither gained nor lost in a chemical reaction but atoms and ions are rearranged into different patterns, bonds are broken and /or formed, and energy is stored or released.

• Evidence or indicators of chemical change include color change, formation of a

precipitate or water, evolution of a gas, and changes in energy. * See teacher note found at end of the “Unit Understandings, Themes, and Concepts”.

Begin this lesson with a DO NOW: (A DO NOW is a task that is assigned for students to do immediately when the bell rings. It should be self explanatory, freeing up the teacher for other routine tasks. The DO NOW is usually written on the board or projected. It is productive way to use the first moments of class in a way that will focus the lesson. In this case, the compounds that are the focus of the DO NOW will be used during this lesson.) The DO NOW: The teacher lists these compounds’ names on the board before class begins, with this instruction to the students: Copy this list in your notebook and write the correct formula for each compound. Also list any properties you know for each compound. • The list: sodium hydrogen carbonate, calcium chloride, water. Launch this lesson by talking about the compounds that the students have experienced thus far. Students are developing understandings about the structure and formulas of compounds and it should be clear that they are formed by dynamic chemical changes. • Briefly review the results of the empirical formula labs. • Explain that now the focus of study will shift to understanding chemical changes both

experimentally and mathematically. Activate this lesson with a series of demonstrations that illustrate the indications of chemical reaction. Include reactions that produce light and are exothermic (combustion of magnesium)



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and that produce light without obvious heat (stir commercial product containing luminol, available from lab supply companies, into water or demonstrate a light stick); produce heat, but not light (CaCl2 and H2O ); absorb heat (Ba(OH)2 + NH4Cl); reactions that involve dramatic color change (KMnO4 and NaHSO3); produce odors (Ba(OH)2 + NH4Cl); produce a gas (decompose H2O2); and that produce a precipitate (AgNO3 and NaCl ). •Students create a data table to use during the demonstrations. The data table should include the

formulas for the reactants and products and their observations for each reaction. • Teacher note: write out the substances’ name on the board, but do not give the formulas.

Students will write the formulas for practice. Omit this step for any compounds where the student would not be expected to know how to write the formula, for example the compounds in a light stick.

• After demonstrating a reaction write out the word equation and have students translate it into

the chemical equation by writing the correct formulas and symbols. • Model balancing the equation, explaining each step. Pick the reactions you want to balance

on the board to illustrate the process of balancing equations. • Discuss Law of Conservation of Matter and why we need to balance equations. Stress that

the coefficients can be interpreted as formula units or as moles. • Students summarize their observations to be turned in for assessment. • Teacher note: Do not get bogged down today in balancing equations. Today’s goal is to

familiarize students with the process. For some it may be a review. The next lesson will focus more on mastering the balancing of equations.

Teaching strategy: To reinforce the understanding of the indicators of chemical change, immediately begin the exploratory activity, Reaction in a Bag. Explain that the students will set up a reaction in a bag that they can consider to be a reaction system. Have students summarize this lesson by writing the word equation for the reaction, and the balanced chemical equation. (Give students the names of the final products for this task. Once they have the correct formulas the equation will be balanced).

Teacher Note on Safety: Review and require students to follow all appropriate lab safety rules, including the wearing of goggles and aprons, clothing safety and the handling of corrosive chemicals and how to waft to detect odors. Students must be thoroughly knowledgeable about the use of safety equipment including the shower, eyewash, sinks, and fire extinguisher.

EQ: How are atoms and ions rearranged in a chemical change? What are the types of chemical reactions and why is it useful to classify reactions?



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Days 19, 20

Understandings: • Matter is neither gained nor lost in a chemical reaction but atoms and ions are

rearranged into different patterns, bonds are broken and /or formed, and energy is stored or released.

• Most reactions can be described by one of five basic patterns and are identified as synthesis, decomposition, single replacement, double displacement, or combustion.

• A system is all the components that define what is being observed or studied. Teacher Note: This lesson will consist of demonstration and lecture on the types of chemical reactions. Demonstrate the reactions of each type; then model balancing the equation. Give students models for balancing the equations. The following are some possible demonstrations and discussion points. Model and exercise appropriate lab safety throughout this lesson. If you are not familiar with a demonstration seek more information and instruction before doing the demonstration in your classroom. Students should take careful notes as the demonstrations proceed. If needed provide a guided note taking sheet. Activating strategy: The first demonstration is a good hook; it is showy enough to get the class involved. For this first demonstration write the balance equation on the board. The students will not be able to write the product formula without further explanation. See the explanation below. Use the accepted terminology for reactants, products, yields, subscript, and coefficient. Demonstration 1: Synthesis Reactions: Burn steel wool in oxygen. 3Fe+ 2O2 ------- Fe3O4 (s) Teacher note: Carry out this reaction in a gas collecting bottle full of oxygen behind a shield. Fill bottle from an oxygen cylinder and leave inverted on a glass plate until ready to use. If an oxygen cylinder is not available in the science department, it may be possible to obtain the oxygen from a tank in the vocational department where welding or automotive courses are taught. A third option is to first generate and collect the oxygen in the lab as a demonstration of the decomposition of potassium chlorate or hydrogen peroxide. Then go back to this reaction. Hold the steel wool with tongs until it is red hot in a burner flame and then plunge it into the waiting oxygen bottle. Use extreme care. The bottle will sometimes crack. Do not substitute any other kind of container for the gas collecting bottle. After the demonstration probe for understanding. Ask students to explain what happened. (Two substances were chemically united into one substance, new bonds were formed, etc.) Probe with questions about the energy involved, and the evidences of reaction. (New product is visible, energy was released.) Ask the students about the mass of the reactants and the products. Ask the students to propose a way to determine if the mass of the reactants and product are equal. Have them discuss their ideas. Next, show students steel wool that has been allowed to set in a moist environment for several days. 4Fe + 3O2--- 2Fe2O3 (rust)



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Explaining the results and balancing the equations: At this point the teacher can go into more detail about the Fe++ and Fe+++ ions and the energy differences involved in the formation of the two iron oxides demonstrated in this lesson. A third iron oxide, FeO, oxidizes to Fe2O3 when exposed to air. The Fe3O4 produced in the first demonstration can be thought of as a combination of Fe2O3 and FeO and can be called Iron (II, III) oxide. Demonstration 2: Decomposition Reactions Decompose hydrogen peroxide rapidly by using manganese dioxide as a catalyst. Pour 250 mL of H2O2 into a graduated cylinder that has a thin layer of MnO2 on the bottom. 2H2O2 2H2O + O2 Discuss the reaction, have students write and balance the equation. Discuss the role of the catalyst in this reaction and expand the discussion to the role of catalysts in general. Teacher note: There are several very dramatic versions of this type of reaction. 30% hydrogen peroxide can be decomposed, but handle with caution. (A local source of 30% hydrogen peroxide is a beauty supply store where it is sold as a bleaching agent.) This demonstration is called “elephant toothpaste” and there are numerous versions of it on the internet. This demonstration is a good place to introduce the topics of kinetics, oxidation/reduction, catalysts and gas production or limiting reagents. Details of the reaction are found at:http://www.carolina.com/chemistry/experiments/elephant.asp Resources: classes.mhcc.edu/enh/ch223_mr/s3/Sp02/toothpaste_JPG.html Another variation is to chop up some liver (chicken, beef, or pork) and put into a graduated cylinder. Pour hydrogen peroxide onto the liver. The Hydrogen peroxide will decompose rapidly in the presence of the catalase enzyme which is abundant in the liver. This approach is very messy but has a certain “yuck appeal”. It is also a great opportunity to connect this course to a vital biochemical process. For background, refer to a biology text. A

Demonstration 3: Synthesis Decomposition Pop the top on a soft drink. Pour some into a beaker. Ask students where the bubbles come from. Explain that under pressure, the CO2 that is forced into the solution tends to combine chemically (but loosely) with the H2O forming carbonic acid. When the pressure is reduced (you reduce the stress on the system when you pop the top, and one of the products escapes), the carbonic acid decomposes. H2CO3 CO2 + H2O In the unopened can, at any given instant, both reactions are occurring in a state of equilibrium, so that this is a reversible reaction.

http://www.carolina.com/chemistry/experiments/elephant.asp



17

CO2 + H2O H2CO3 This is an opportunity to help students build conceptual understanding of a chemical system, equilibrium, reversible reactions, Le Chatelier’s Principle, and properties of gases which are covered in greater detail in later lessons. Demonstration 4: Single Replacement Mg + 2HCl ---- MgCl2 + H2 Have students discuss the reaction, write and balance it. Then ask students to think back to what they learned about trends on the periodic table and predict what would happen if iron were used instead of magnesium. Discuss the activity series and how to use it to predict whether a single replacement reaction will happen. If time permits, use one class period for an activity series lab. Demonstration 5: Double Replacement K2Cr2O7(aq) + 2AgNO3(aq) --- Ag2Cr2O7(s) + 2KNO3(aq) This demonstration is most effective on a light box or overhead projector. Use a dilute solution of potassium dichromate. Use just enough to get a pale orange solution. Add silver nitrate solution using a plastic pipette. This reaction produces a vivid brick red precipitate, silver dichromate. Follow up this double replacement by stirring a small amount of NaCl into the beaker that contains the silver dichromate. Ag2Cr2O7(s) + 2NaCl(aq) --- Na2Cr2O7(aq) + 2AgCl(s) The sodium dichromate will be light yellow and the silver chloride will be a white precipitate. Allow the precipitate to settle to show the class. Discuss the ionic nature of this reaction and demonstrate how this type of reaction can be represented in ionic form. Introduce the idea of net ionic equations and illustrate with these reactions. Demonstration 6: Combustion Define combustion as exothermic, rapid oxidation. Burn several different hydrocarbon compounds to illustrate combustion where water and carbon dioxide are formed. Light a paraffin candle, light a lab burner, strike a match. Since paraffin is a mixture of alkanes, its formula is represented as CnH2n+2. The generic equation for the combustion of an alkane compound is:



18

CnH2n+2 + __O2 --- __ CO2 + __ H2O Explain that the combustion of methane, the simplest alkane, which is often added to propane, would react with oxygen in the following way. CH4 + 2O2 --- CO2 + 2 H2O Propane which is the gas used in many labs, would react in this way: C3H8 + 5O2 --- 3CO2 + 4H2O Have students list all the similarities of these reactions. Have the students develop the definition of combustion of a hydrocarbon based on these similarities. After this definition is established, the following applications and extensions can be addressed.

• Explain the difference in complete combustion and incomplete combustion of a hydrocarbon. Discuss the conditions under which each occurs. (Incomplete combustion occurs at lower temperatures and when the oxygen supply is the limiting reagent. Under these conditions carbon monoxide is produced. This is a real world application of the effect of a limiting reagent and/or the effect of temperature on a reaction.)

• Compare cellular respiration to combustion of sugar as an extension and connection to

biology. Point out that not all combustion reactions are hydrocarbon combustions. The burning of steel wool was a combustion reaction as well as a composition reaction. Another demonstration of combustion of a non-hydrocarbon is the burning of sulfur in an oxygen bottle; set this up the same way as the steel wool was set up for the first demonstration. Have students extend their definition to compounds that are not hydrocarbon compounds. Summarizing Task: List several reactions on the board. Have students write the word equation, the chemical equation and then practice balancing these. The final step is to identify what kind of reaction each is. Examples: Combustion of magnesium Addition of zinc to hydrochloric acid The reaction between lead nitrate and potassium iodide Formation of calcium oxide and carbon dioxide from calcium carbonate. Resource for many other demonstration options: Links - Demonstration Experiments - Chemistrywww.uni-regensburg.de/Fakultaeten/nat_ Fak_IV/Organische _Chemie/Didaktik/ Keusch/link.htm

http://www.uni-regensburg.de/Fakultaeten/nat_Fak_IV/Organische_Chemie/Didaktik/Keusch/link.htm

http://www.uni-regensburg.de/Fakultaeten/nat_%20Fak_IV/Organische%20_Chemie/Didaktik/



19

Day 21,22

E.Q. How are atoms and ions rearranged in a chemical change? What is a balanced chemical equation and what does it tell us? What are the types of chemical reactions and why is it useful to classify reactions? Understandings:



Activate this lesson with this hook: Have students go back to their notes from Day 18. Review the reactions and ask students to determine what kind of reactions they were. Teach the details of balancing equations. There are many useful website resources. One such source that can be used to teach and reinforce conservation of matter, the types of reactions and the skills of balancing a chemical equation is: http://dbhs.wvusd.k12.ca.us Use distributed practice; monitor and adjust instruction so that all students develop this skill and understanding. Summarize lesson with a brief formative assessment over balancing equations. Homework: Give students sets of reactions to write the formulas, determine the kinds of reactions and balance the equations. This assignment could be differentiated in level of complexity and length. Also assign a quiz over balancing equations to be given during the next class.

Day 23

E.Q. How are atoms and ions rearranged in a chemical change? What is a balanced chemical equation and what does it tell us? What are the types of chemical reactions and why is it useful to classify reactions? Understandings:



Today students will carry out a laboratory exercise to gain first hand experience with the five types of reactions. There are various versions of this lab available in most lab books or on-line. http://www2.ucdsb.on.ca/tiss/stretton/chem3/Lab_5_Reaction_Types.htmlhttp://intranet.landmark.edu/ctolman/chem/reactions.htm Homework: Assign performance task, Analysis of Reactions to be turned in on Day 25.

http://dbhs.wvusd.k12.ca.us-/

http://www2.ucdsb.on.ca/tiss/stretton/chem3/Lab_5_Reaction_Types.html

http://intranet.landmark.edu/ctolman/chem/reactions.htm



20

Teacher note on safety: Review and require students to follow all appropriate lab safety rules, including the wearing of goggles and aprons, clothing safety, procedures for handling chemicals, fire safety, and lab burner safety. Students must be thoroughly knowledgeable about the use of safety equipment including the shower, eyewash, sinks, and fire extinguisher.

Day 24

This day will be used for students to complete lab work and reports. Time can be used to review the understandings of this unit, and to work on the performance task, Analysis of Reactions. Teacher will conference with individuals to facilitate this task.

Day 25 Summative Assessment: Test over compounds, reactions, and equations.

Constructed response item to include is the Reaction Types Concept Map.

Misconceptions Students may think that if a balanced chemical equation can be written, the reaction can occur. Students may think of these pairs of words as synonyms:

• atom and element • molecule and compound

Students may think that the elements are found in their elemental form in nature. Language Chemical bond; ionic bond; covalent bond; molecule; formula; ion; cation; anion; precipitate; empirical formula; molecular formula; subscript, hydrate, anhydrous, reactant, product, yield, coefficient Web Resources:

http://ithacasciencezone.com/chemzone/chelinks.htm. This website has a wealth of links and resources for this unit as well as for other chemistry topics.

Ionic bonding and properties: Atoms and subatomic particles United streaming has several video clips available on chemical reactions (including teacher

guides and black line masters for students). www.unitedstreaming.com .Schools/ systems can obtain access and passwords. http://www.visionlearning.com/library/x_linker.php?moid=2117&l= This site gives a

comprehensive treatment of the topics in this unit. http://www.800mainstreet.com/4/0004-0010-formula-ionic.html for Day 2 and other helps. http://www.dhmo.org www.cci.unl.edu/Chemistry/DoChem/DoChemKeys.html http://129.93.84.115/Chemistry/DoChem/DoChem096.html http://www.chemtopics.com/unit02/unit2f.htm http://www.thecatalyst.org/ http://filebox.vt.edu/users/ckeel/lps.htm http://www.chemreview.net/download_instructions.htm

http://ithacasciencezone.com/chemzone/chelinks.htm

http://www.800mainstreet.com/4/0004-002-Periodic.html

http://www.unitedstreaming.com/

http://www.visionlearning.com/library/x_linker.php?moid=2117&l=

http://www.800mainstreet.com/4/0004-0010-formula-ionic.html


http://www.cci.unl.edu/Chemistry/DoChem/DoChemKeys.html

http://129.93.84.115/Chemistry/DoChem/DoChem096.html

http://www.chemtopics.com/unit02/unit2f.htm

http://www.thecatalyst.org/

http://filebox.vt.edu/users/ckeel/lps.htm

http://www.chemreview.net/download_instructions.htm



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Other Resources

The formula construction materials are available from various chemistry supply companies in kits, but can be homemade.

Most lab books have an empirical formula lab, and a formula of a hydrate lab available.



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Appendix PERFORMANCE TASKS FOR UNIT THREE

Properties of Compounds Give students labeled samples of ionic and covalent compounds. Do not indicate whether they are ionic or covalent. Some examples include sugar, salt, vinegar, dilute HCl, dilute NaOH, and oil (if you don’t mind getting messy!). Student pairs or teams will design procedures for testing and recording data on the properties such as conductivity, solubility, hardness, brittleness, and melting point. After teacher approval, students will carry out their procedures, and collect their data. In order to analyze their data, students should research the general properties of ionic and covalent compounds. After doing this, each sample should be identified as ionic or covalent. Students incorporate all these steps into a complete lab report. Teacher notes: a. All safety rules must be strictly enforced, including the wearing of goggles and aprons, fire, heat,

and electrical safety, and safe handling of chemicals and glassware. I mini-lesson on some of the necessary techniques, equipment, and procedures should precede this lab.

b. Conductivity testers can be constructed using 9-volt batteries, and LED bulbs.

c. Construct rubric and discuss with students during the pre-lab.

Dihydrogen Monoxide Environmental Issue Project This project can be done if time allows and could be a project done near the end of the year. It impresses on students the importance of multiple data sources and careful data analysis. Students research DHMO and write a persuasive letter with a petition to ban DHMO. They must get at least 10 adults to sign their petition. Only after obtaining signatures do they reveal the common name for DHMO. This can be done by sending an “official memo” from the chemistry department explaining that DHMO is really water, and that the students were conducting an exercise in the importance of basing judgments on thorough data. Students love to pull this one on teachers and administrators. As this activity gets repeated, successive groups of students will have to seek out the new teachers and other adults to find those who do not already know about DHMO. For more on DHMO go to http://www.dhmo.org/




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Valence Graphic Organizer

Group 1

Group 2

Group 13

Group 14

Group 15

Group 16

Group 17

Group 18

Number of valence electrons for the atoms of this group

Common charge of the ions of this group

Common valence

Lewis dot structure of the atoms of this group

Lewis dot structure of the ions of this group

The Octet Game- Crazy Eights This card game is meant to be used as an activating strategy to initiate instruction on bonding and the octet rule. It is also useful to reinforce or re-teach this concept with students who need more instruction. To win this game, a player must “go out” by melding all cards in pairs, triplets, or quads where the total number of electrons equals eight, or multiples of eight. Each meld total could be 8, 16 or 24. (No meld can contain more than two elements in this game and each meld must be composed of one red element and one blue element, but up to five cards may be used to make the meld; the more cards the more points!) Examples: A meld could be one Na card and one Cl card. (pair)

A meld could be two Na cards and one O card. (triplet) A meld could be one Al card and three F cards. (quad)

Make cards representing elements of groups 1, 2, 13, 15, 16, and 17; A template is given below. To use the template, enlarge, and cut out. Laminate if possible so that the cards will last longer. Make one deck of cards per group of four. The cards should be printed with the red or blue lettering as shown here in order to follow the game rules. If that is not possible, then the cards should be marked in some way to distinguish the metals from the nonmetals. A deck needs to have 54 cards, (four sets of the template per deck). How to play: The dealer deals six cards to each player. The deck is placed in the center of the table and the top card is turned up to begin the discard pile. The players then meld any sets of eight that they receive in their hand. Play proceeds by the player to the right of the dealer may either pick up the discard card, or draw from the deck. The player then discards. Play continues around the table, until one player can meld all cards and “go out”. In going out the player may choose to discard one card, or meld all cards. Score: 10 points for going out; 10 points for a meld that contains 2 cards; 20 points for a meld of three cards; and 20 points for a meld of four cards. Player with the highest score at the end of a set amount of time wins, or agree to play to a certain number of points. (First player to score 100 points wins).

CARD TEMPLATES

Na

1e-

Li

1e-

K

1e-

Be

2e-

Mg

2e-



24

-P

P

P

P

P

Al

3e

Ca

2e-

Sr

2e-

B

3e-

Ba

2e-

Formula Models Give students a list of compounds and a set of paper ion/atom models. The student will construct models of the ionic and/or covalent compounds on the list. The student will write the correct formula, if given the name, or write the correct name when given the ions or elements in the compound. The specifics for modeling ionic compound are given below. Models for covalent compounds can also be constructed by writing the oxidation numbers on the models. Ion Models: Reproduce these ion models, making at least one sheet per student pair. Laminate if possible and then have students cut them out. Make an enlarged demonstration set out of poster board or card stock. Glue flexible magnet tape to the backs, or use magnetic sheets from the craft store. These can be used to model the makeup of ionic compounds on a metallic backed board or surface in the classroom.

N

5e-

O 6e-

F

7e-

P

5e-

S 6e-

Cl

7e-

Br

7e-

I

7e-



25

Ways to use these manipulatives: 1. Give the students names of compounds such as:

Sodium chloride ( Do not give the formula.) Student pairs then check their graphic organizer, if needed, to determine the charges of the required ions. The pair then constructs the model of the compound, and writes the formula, based on the number of each ion used. The teacher monitors to facilitate and check for accuracy. Continue this procedure, giving compounds that require more thought, and more ions!

Sample list: calcium fluoride, magnesium oxide, lithium oxide, sodium bromide, strontium chloride, aluminum sulfide, potassium nitride. At this point, two pairs may realize they must share to demonstrate a correct model of the compound unless extra copies of the ions are available.)

2. Place a model on the board, such as:

Have students list the names and formulas for as many compounds as they can, that have this

2-

3-

1+ !

3+ !

!

!

2+ !

!

1-

2-

3-

1-

1+ !

2+ !

! 3+ !

!

!

+2 !

! -1

-1



26

same pattern of balanced charges. This task may be done as a silent round robin. Repeat, differentiate.

Instructions for silent round robin: Groups of four have one sheet of paper, laminated card stock, or a white board. The first student writes the formula for one compound, then passes the list to the right. Each member in turn, adds to the list. If a member cannot think of another answer, that member may pass after trying for at least ten seconds to come up with an answer. If a member writes an answer that is incorrect, the next member to receive the list may go back and correct the previous answer. This task is most effective if the “silent” aspect of the activity is maintained. This task may also be done for warm-up, formative practice, or as a group competition.

3. After instruction on the valence of the transition metals this activity could be repeated to practice compounds that exhibit more than one common valence.

4. One way to differentiate instruction and assessment by using these manipulatives is to allow students who need them to have them available during quizzes or tests.

Discrepant Event with Properties of Water Give groups of four, a re-sealable plastic sandwich bag containing two squares of glass, one plastic pipette filled with water, and five toothpicks. Step one: Students make a small puddle of water on the counter top. (Alternatively, see how many drops of water can be placed on a penny before the water spills over the edges.) Observe this convex surface. Why does the meniscus in a graduated cylinder filled with water have a concave shape? Step two: Place two drops of water on one of the pieces of glass. Place the second piece of glass on top of these drops and press the pieces of glass together like a sandwich. Attempt to separate the two pieces of glass by pulling directly up and down on the two pieces. Why is this so hard to do? Step three:

Bend 5 wooden toothpicks in half so that each toothpick forms a “V” but does not break apart.

Place the bent toothpicks on the center of a dry, smooth surface, arranging them so that the points of the Vs make a small circle in the middle. It will look like a flower.

Drop two or three drops of water into the center of this circle without disturbing the toothpicks.

Record your observations. What happened to the toothpicks? Why?

Write an essay explaining how the unique properties and molecular structure of water caused the phenomena just observed.

Teacher note: These demonstrations are very simple, but are favorites with the students.



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Brief explanations:

Step one- surface tension results from cohesion and adhesion due to the hydrogen bonds between the polar covalent water molecules.

Step two- cohesion and adhesion due to the hydrogen bonds between the polar covalent water molecules holds the glass together.

Step three- capillarity of the water into the spaces in the toothpick (which is made of hollow plant cells) as a result of the hydrogen bonds between the polar covalent water molecules. “Water” you thinking? Performance Assessment Choice One: Write an analytical essay based on the understandings in this unit to explain how atoms and ions bond. The title alludes to the uniqueness of the bonding in and between water molecules and should prompt the writer to consider the range of possibilities that exist in bonding. To prepare for writing, review the essential questions and what you know about each. Include the following topics.

differences in the properties of ionic and molecular compounds how ionic and covalent bonds form how electron arrangement affects bonding how bonding affects structure how structure affects properties

In your essay, use specific examples to support your statements. Also, be careful to use the language associated with these concepts appropriately. Choice Two: (This may be used when a differentiated assignment is needed.) Construct a concept map that illustrates the key points indicated in choice one.

PAT Formula Bee Conduct this activity in the format of a spelling bee. The contestants stand, until they miss one. This can be used as a warm-up before a quiz. A variation: groups write the formula of a white board and all groups that get the formula correct score a point.

Reactions in a BagTask

http://www.teamcamelotonline.com/reaction%20in%20a%20bag.pdfAn Endothermic Reaction

Reactions in a Bag- This task is written up in various laboratory guides and demonstration books. In this unit, the reaction should be approached as an inquiry activity as a bridge from bonding and formulas to reactions and equations.



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http://www.teamcamelotonline.com/reaction%20in%20a%20bag.pdf


Teacher Procedure:

Have students complete the DO NOW as described in the lesson. Establish lab partners or groups. Have each group’s runner pick up the materials for their group. Students will need to obtain approximately 5 g. of the NaHCO and of the CaCl3 2. It may be

expedient to have pre-measured the chemicals into small lab containers or into snack size re-sealable plastic bags for each group.

Review safety with students The language of chemical reactions should be embedded in the context of this lesson:

reactant, product, endothermic, exothermic, yields. Student Procedures: Prelab

Complete DO NOW Review safety with teacher Establish group roles Runner picks up materials Make micro-spatulas and ampule (See instructions below.)

Materials : sodium hydrogen carbonate, 5 g calcium chloride, 5 g water, 5 mL phenol red solution one zip-top plastic bag

lab scissors four disposable pipettes

Micro-scale technique: Cut the bulbs of two plastic pipettes at an angle to create micro-

spatulas. Cut the third pipette across stem near where it joins the bulb to make an ampule. The fourth pipette is for the water.

Part I (Teacher note: If Part I was done as part of lesson 13, unit 3, then review by demonstrating it again for the class. Then proceed with the rest of the lab.)

Using one of the spatulas, place two scoops of calcium chloride in one corner of the plastic bag. Using the other micro spatula, place one scoop of sodium hydrogen carbonate in the other corner, so that the two compounds are not in contact with each other.



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CUT PIPETTE ALONG DASHED LINE TO MAKE AMPULE.

CUT PIPETTE ALONG DASHED LINE TO MAKE SPATULA.

Fill the ampule with phenol red and place in the plastic bag. Use the remaining pipette to add approximately 2 mL of water to the bag. (one bulb full of water)

Immediately press the air out of the bag and close it completely. Once the bag is sealed, squeeze the ampule of phenol red out into the bag, and mix the four

compounds together. Observe carefully and record observations that are signs of a chemical change.

Part II

Devise a plan for investigating which compounds react to give which results. Present this plan for approval to the teacher. Obtain any other equipment required in your plan. (more reactants, bags, pipettes, etc.) Carry out your approved procedure Keep careful data on what happens in each case. Note that the phenol red is a solution of phenol red in water

Post Lab: Students should complete their data table and observations. These should be assessed. Explain to students that by the end of this unit, they will be able to trace the series of chemical reactions that actually took place in the bag and explain how atoms and ions were rearranged to produce the final products. Teacher note: the purpose here is for the students to mix two of the reactants at a time to see what happens. The following is a key. CaCl + H O Hot 2 2NaHCO + H O Cold 3 2CaCl2 +phenol red C19H13O Hot 5NaHCO + phenol red C3 19H13O Cold 5CaCl2 + NaHCO + phenol red C3 19H13O Hot 5

The reactions described in the following links can be conducted as a mini-lab. Students carry out the procedures, and record their data. Students must observe all lab safety rules. Data for each reaction should be recorded and then discussed by the class. http://www.teamcamelotonline.com/reaction%20in%20a%20bag.pdfAn Endothermic Reaction Teacher Background Note: The students will notice changes in temperature, the production of a gas, and the color change. The word equation is Calcium hydrogen carbonate + Calcium chloride sodium chloride, calcium carbonate, carbon dioxide, and water. These products are actually the result of a series of changes, but the summary equation given above should be used with this lesson. The summary given below can be used later in this unit after studying the types of reactions.



30

http://www.teamcamelotonline.com/reaction%20in%20a%20bag.pdf


• The dissolving and dissociation of the CaCl and NaHCO 2 3

• The formation of Ca(HCO3) and NaCl from the reactants (double replacement) 2

• The formation of CaCO , CO2 and H O from the Ca(HCO ) (decomposition) 3 2 3 2 CaCl + 2NaHCO2 3 ------ Ca(HCO3)2 and 2NaCl Ca(HCO3) ------- CaCO , CO2 and H O 2 3 2 Tie it all together: Throughout this unit, this reaction system can be used to illustrate concepts of solvation, energy change, gas pressure, and equilibrium. While these concepts will be covered in greater detail in Unit Four, Exploring Systems, the concepts can be introduced in the context of this task.

Analysis of Reactions Performance Task for Summative Assessment: Students outline all the physical and chemical changes that occurred in the bag reaction and relate the changes to solutions, energy change, gas pressure, and equilibrium. Balanced equations should be written for the reactions that occurred and the type of reaction should be identified.

Concept Map Performance Task: Reaction Types Design a concept map that diagrams the five types of chemical reactions studied in this unit. Show how elements and compounds are changed through these reactions. Show connections and relationships between the kinds of reactions, the type of reactants (elements, ionic and covalent compounds) and products (elements, ionic and covalent compounds). It is not necessary to show actual equations in this map. A student could use the generic equations below as a starting place for the concept map, using a key for letters. A sample completed concept map follows. Students should be allowed some flexibility in the design, and the product could be produced using appropriate software, or it could be done using a traditional format.

Although one goal of the concept map is for it to be so clear that no further explanation is needed, the student should be able to discuss the reasoning behind the design of the map. Generic Reaction Formats: Composition (synthesis): A +X AX Decomposition: AX A + X Double Replacement (Ionic reactions): AX + BY AY + BX Single Replacement (Displacement): AX + B BX + A; AX +Y AY +X



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SAMPLE CONCEPT MAP OF TYPES OF REACTIONS



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Composition

Water

Combustion (rapid oxidation)

Oxygen

Organic compounds

Covalent Compounds

Carbon dioxide

Precipitate or

Elements

Molecular compound

Ionic Compound 3

Compound 4

Double Replacement

Ionic compound 2

Ionic compound

decomposition

Ionic Compounds

Compounds

New ionic compound

replacement

Single replacement

Rubric for Concept Map: Reaction types

Types of reactions

Map shows relationship between reactants and products correctly and relationship to other reaction types correctly.

Map shows relationship between reactants and products but

Reaction type is shown, but relationship between reactants and products is unclear; relationship to other reaction types is adequate.

Reaction type is shown but is unclear, or incorrect; relationships to other reaction types is missing.

Reaction type is missing.

relationship to other reaction types is unclear or missing.

15 points 12 points 10points 5 points 0 points

Composition Decomposition

Single Replacement Double Replacement Combustion

Design of concept map

Design and organization of map indicate a clear overall analysis of the reaction types and can be understood without additional explanation.

Design of the map indicates acceptable understanding of the reaction types but not all parts are clear.

Necessary information is present, but design of the map is hard to interpret.

Design indicates lack of understand-ing of reaction types. Re-do and resubmit for reassess-ment within three days.

This is not a concept map! Or no map is present. Submit within three days for assessment

Additional explanation is needed.

25 points 20 points 15 points 10 points 0 points Total points



33



34

Introduction Unit Framework Title Exploring Change

Documents