CHAPTER 6 Elements and the Periodic Table

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CHAPTER 6 Elements and the Periodic Table

KEY QUESTION: Are the elements in the periodic table organized according to their

physical and chemical properties, or according to their atomic structure?

Key Concepts Vocabulary

Elements cannot be broken down into simpler substances.

Metals and non-metals have characteristic physical properties. Elements are organized according to their atomic number and electron arrangement on the periodic table. Atomic models evolved as a result of experimental evidence.

Atoms contain protons and neutrons in a central core surrounded by electrons.

Elements can be both beneficial and harmful to humans and to the environment. element element symbol compound metal non-metal metalloid chemical family alkali metal

alkaline earth metal noble gas halogen period atom electron proton neutron atomic number mass number isotope atomic mass Bohr-Rutherford diagram

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Skills in this Chapter 6.1 6.2 6.3 6.4 6.5 6.6 6.7 6.8 Inquiry Skills Questioning X X X Hypothesizing X Predicting X X Planning X Controlling Variables X X Performing X X X X X X X X Observing X X X X X X X Analyzing X X X X X X X X Evaluating X X X X Communicating X X X X X X X X Decision-Making Skills

Defining the Issue

Researching X X

Identifying Alternatives

Analyzing the Issue X

Defending a Decision

Communicating X X

Evaluating X X

POSSIBLE MISCONCEPTIONS Identify

• Students may believe that any material that looks uniform is an element.

Clarify

• Elements do look uniform, but so do other materials, such as compounds and homogeneous mixtures.

Ask What They Think Now

• At the end of the lesson, ask, What is an element? (A pure substance that cannot

be broken down into simpler substances—one of the building blocks of other substances)

TEACHING NOTES

• Have students look at the chapter opener photo on page 206 of the Student Book and read the caption.

o Ask, What do you think the letters, colours, and numbers on the table

might mean? Have students write their responses in their notebooks so that

they can compare their initial knowledge with what they learn during the chapter.

o Explain that the word periodic refers to something that occurs in a repeating pattern. Ask, Why are the days of the week periodic? (They

occur in a repeating pattern.) What are some events in nature that are periodic? (Sample answers: phases of the moon, day and night, seasons,

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o Ask, How do you think elements are organized in a periodic table? (Sample answer: They should be organized in repeating patterns.)

• Have students read the Key Question. Review physical and chemical properties with

them. Tell them that copper is one element on the periodic table. Ask, What are some properties of copper? (sample answer: reddish colour, malleable, conducts electricity) Why might it be possible to organize elements on the periodic table according to both their properties and their atomic structure? (sample answer: The physical and

chemical properties might be the result of atomic structure.)

ENGAGE THE LEARNER Chapter Introduction

• Have students review the concept map and think about how the information in

Chapter 6 fits within the Unit C, Atoms, Elements, and Compounds. Point out that the

properties of matter discussed in Chapter 5 are used to help determine the placement of elements in the periodic table in Chapter 6. The chemical compounds studied in Chapter 7 are formed from the elements studied in this chapter. The location of each element on the periodic table helps predict whether and how the element reacts with other elements to form compounds.

• As a class, review each Key Concept. Use the following prompts to activate prior

knowledge and engage students in the topic of the chapter (from left to right):

o For the first Key Concept, show them an image of a large diamond. Tell them

that diamond is made of the element carbon. Ask, what would be the result of dividing a piece of carbon—an element—into smaller and smaller pieces? Would it become something new? (sample answer: no, it would become tiny

pieces of carbon) Emphasize that no matter how small the pieces get, they are still carbon and cannot be broken down into anything simpler.

o For the second Key Concept, ask, What are some physical properties of metals? (sample answer: shiny, hard, bends) Explain that students will learn

which elements are metals and how their properties compare to those of elements that are not metals.

o For the third Key Concept, tell students that they will learn that each element

is composed of a unique type of atom with its own atomic number and arrangement of electrons.

o For the fourth Key Concept, ask, What materials would you use to model the structure of an atom? How would you arrange these materials to make your model? (Answers will vary.) Point out that throughout the development of

atomic theory, atomic models and their names have changed to reflect current scientific knowledge.

o For the fifth Key Concept, ask, What is the charge of each particle in an atom? (Protons are positive; electrons are negative; neutrons are neutral.)

o Have students read the sixth Key Concept. Then show them a label from a

fertilizer container and ask, What elements are present in this chemical fertilizer? (sample answers: potassium, nitrogen, and phosphorus) What are some elements that are toxic to organisms in the environment? (sample

answers: arsenic, mercury) Point out that some elements can be benign or even beneficial in low concentrations but toxic in high concentrations.

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Engage in Science

• To engage students’ interest in the upcoming chapter, have students look at the picture of the Mad Hatter and the photo of the boy with a fish. Have them try to connect the two pictures. Ask students whether they have read Alice’s Adventures in Wonderland. Ask, Why was the Mad Hatter called the Made Hatter? (sample answer:

He made hats and behaved strangely.) Emphasize that here the word mad refers to

acting strangely, not being angry.

• Have students read the article. The purpose of this page is to highlight the fact that science and chemistry relate directly to every day life, health, and safety.

• Point out that contact with liquid mercury (or a mercury compound) is not the only way to get mercury poisoning. Liquid mercury vaporizes, and the vapor is as toxic as the liquid. In the 19th century, many gold miners in North America used liquid mercury to collect gold in their sluice boxes and dredges. Later they burned the mercury off, often poisoning themselves with mercury vapor.

• Dental amalgams contain mercury and are used to fill teeth. An amalgam is an alloy of mercury and one or more other metals. Some new formulations for dental fillings do not contain mercury.

• The amount of mercury a person ingests by consuming fish (or shellfish) depends on the amount of fish eaten and on the amount of mercury contained in the flesh of the fish. Animals near the top of the food chain tend to have higher concentrations of mercury. For example, shark, swordfish, halibut, and golden bass (golden snapper) normally have mercury concentrations of 0.97–1.45 ppm (parts per million). Fish lower on the food chain, such as salmon, scallop, catfish, and flounder normally have mercury concentrations of about 0.05 ppm. But any fish that lives in

mercury-contaminated waters may have greater mercury concentrations than usual. • Have students list the types of fish they like to eat and use the Internet to find the

amount of mercury those types of fish commonly contain.

What Do You Think?

• Review each photo with students. Have volunteers answer each question posed. Encourage students to debate and defend their positions. Emphasize that everyone should feel free to argue their position but that students should keep in mind that their views might change as they read the chapter.

• To prompt students to connect the photos with their own experiences, ask the following questions.

o Photo #1: Sometimes water is called H2O. How might this name tell you

whether water is an element or not?

o Photo #2: What are the physical properties of metals? How are metals

used in everyday life?

o Photo #3: Are the names (or abbreviations) of the elements shown in the

photo in alphabetical order?

o Photo #4: If it were easy to change iron into gold, what would happen to

the price of gold?

o Photo #5: What kind of dosage information is included on the labels of

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o Photo #6: What is an educated guess? How do scientists construct a

theory?

• Poll the class on each question. Revisit the poll results at the end of the chapter in the What Do You Think Now? section.

Focus on Reading

•

Distribute BLM 0.0-26 Reading Strategies Checklist for students to use for this

activity.

READING TIP

Draw students’ attention to the Reading Tip in the margin. Encourage them to look for and study any Reading Tips in the chapter sections, as the tips describe simple but effective ways to improve one’s writing.

DIFFERENTIATED INSTRUCTION

Have all students write the Key Concepts on separate pages of their notebooks.

Verbal/linguistic students should write notes in full sentences for each Key Concept

as the chapter progresses. Visual/spatial and artistic students can add sketches and diagrams to their notes. Aural students should write single-word notes that they can use to orally review. At the end of the chapter, review the students’ notes. Ask students to describe, in written or oral form, how their understanding of the Key Concepts changed as a result of completing the chapter.

You may wish to distribute BLM 0.0-10 Chapter Key Concepts for students to use to

record their notes and observations relating to each of the Key Concepts.

Have verbal/linguistic learners summarize the Key Concepts in a play, skit, or poem.

Check the summaries to make sure they are accurate.

Have students who are interested in computers set up a class blog or social networking link for posting notes, observations, reports, images, source material, links, and other forms of information.

Distribute BLM 0.0-1 Graphic Organizer: K-W-L Chart to students. Students with

different learning styles can use the chart differently. Logical/mathematical learners can use the charts for written notes. Visual/spatial learners can add images (sketches and diagrams) to their charts. Verbal/linguistic students might use sound-recording equipment to take auditory notes for their charts. Have students keep working on their charts as the chapter progresses.

• Verbal/linguistic learners can research mercury contamination of a Canadian lake or waterway. Students may want to investigate questions such as the following: What kinds of fish live in the lake or waterway? What was the source of the mercury pollution? How has the mercury contamination made its way through the food web? What restrictions have been placed on fishing in the lake or waterway?

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English Language Learners

Have students make flashcards to record unfamiliar terms from the chapter. Each flashcard should have the term on one side, and its definition (plus a sample sentence, if desired) on the other. Students can use the flashcards to play games and review terms.

Literature Connection

Read sections from Alice’s Adventures in Wonderland that show examples of the odd

behaviour of The Mad Hatter out loud in class. Have a discussion about the hatter’s odd behaviour. Do students think that the author (Lewis Carroll) used the behaviour of hatters that he knew as a basis for the character he created?

Social Studies Connection Have students locate Kenora, Ontario on a map of Ontario.

Ask, Why might mercury pollution near Kenora spread to other parts of Ontario?

(Sample answer: The area around Kenora contains many lakes and waterways—the polluted river could carry mercury into lakes and waterways downstream.)

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6.1 A Table of the Elements Time 45–60 minutes Vocabulary element element symbol compound metal non-metal metalloid Skills Performing Observing Analyzing Communicating

Equipment and Materials per group:

• element samples (e.g., magnesium, sulfur, silicon, copper, iron, nickel, aluminum, tin, silver, gold, zinc, carbon)

• large periodic table (or paper squares, each with an element name written on it)

Literacy Resources Assessment Resources

Assessment Rubric 1: Knowledge and Understanding Assessment Summary 1: Knowledge and Understanding

Other Program Resources

BLM 6.1-1: Periodic Table Concept Map

Nelson Science Perspectives 9 website

www.science.nelson.com

Related Resources

Rigden, John, Hydrogen: The Essential Element, Harvard University Press,

2003

Street, Metals in the Service of Man, Penguin, 1999

Exam View ®Test Bank

Teacher eSource SUITE Upgrade

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OVERALL EXPECTATIONS

• demonstrate scientific investigation skills in the four areas of skills

• assess social, environmental, and economic impacts of the use of common elements and compounds, with reference to their physical and chemical properties

• investigate, through inquiry, the physical and chemical properties of common elements and compounds

• demonstrate an understanding of the properties of common elements and compounds, and of the organization of elements in the periodic table

SPECIFIC EXPECTATIONS Scientific Investigation Skills

• gather data from laboratory and other sources, and organize and record the data using appropriate formats, including tables, flow charts, graphs, and/or diagrams

• analyze and interpret qualitative and/or quantitative data to determine whether the evidence supports or refutes the initial prediction or hypothesis, identifying possible sources of error, bias, or uncertainty

• communicate ideas, plans, procedures, results, and conclusion orally, in writing, and/or in electronic presentations, using appropriate language and a variety of formats

Relating Science to Technology, Society, and the Environment

• assess social, environmental, and economic impacts of the use of common elements or compounds

Developing Skills of Investigation and Communication

• use appropriate terminology related to atoms, elements, and compounds, including, but not limited to: boiling point, mixtures, particle theory, pure substances, and viscosity

• conduct an inquiry to identify the physical and chemical properties of common elements and compounds

Understanding Basic Concepts

• distinguish between elements and compounds

• describe the characteristic physical and chemical properties of common elements and compounds

• identify and use the symbols for common elements and the formulae for common compounds

KEY CONCEPTS

• Elements cannot be broken down into simpler substances. • Metals and non-metals have characteristic physical properties.

EVIDENCE OF LEARNING

Look for evidence that students can

• describe elements and distinguish them from compounds

• relate element symbols to elements and find them on the periodic table • describe metals, non-metals, and metalloids by their characteristic properties

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SCIENCE BACKGROUND Choosing Names and Symbols

• The International Union of Pure and Applied Chemistry (IUPAC) is the organization that names elements and assigns element symbols, thus ensuring standardization of names and symbols worldwide.

• Some element names are based on the names that were commonly used for the substances, such as oxygen and carbon. Some elements, such as bohrium and einsteinium, are named after famous scientists. (Bohrium is named after the Danish physicist Niels Bohr; Einsteinium is named after the German-born physicist Albert Einstein.) Still other elements, such as berkelium and francium, are named after the locations where they were discovered (Berkeley and France).

• In most cases, elements have one- or two-letter symbols based on the name of the element. Some elements have symbols based on the Latin names of the elements, such as gold (Au for aurum), silver (Ag for argentum), and lead (Pb for plumbum).

Not all elements can have a symbol consisting of the first letter or first two letters of its name. Ten elements, for example, start with the letter c, and several of these start

with the same two letters, ca (e.g., californium, carbon, and calcium). Each symbol

has to be unique, so some must consist of the first letter of the element’s name, plus another letter from elsewhere in the name. For example, the symbol for californium is Cf.

Compounds

• Not just any two elements can form a compound. Compounds such as water (H2O)

and carbon dioxide (CO2) contain two or more non-metals. Compounds such as table

salt (NaCl) and sand (SiO2) contain a metal or a metalloid with a non-metal. But two

metals will not form a compound. Metals tend to lose electrons to form compounds. Two atoms that both tend to lose electrons will not chemically join.

• Although hydrogen often loses its electron in chemical reactions as if it were a metal to form a positively charged ion, H+, ,it will react with certain metals to form a negatively charged hydride ion, H-, as well .

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• Students may think that all metals have the same properties.

Clarify

• Metals share many properties, but to different degrees. For example, some metals

are shinier than others, and some are better conductors than others. Some, like cesium have melting points so low they melt in your hand. Others, like tungsten have melting points well over 2000 o_{C. Malleability of metals also varies considerably. Iron, for}

example, is brittle while sheets of aluminum can easily be folded. Also, some metals have properties that other metals don’t have, such as reactivity with other elements.

• At the end of the lesson, ask, What are some examples of metals with different properties? (sample answer: Iron is hard and ductile, while sodium is soft and not

ductile.)

TEACHING NOTES Engage

• To engage students’ interest, have them examine their pencils (wooden pencils will serve). Write the terms element, compound, metal, and non-metal on the board. Have

students classify each part of a pencil into one or more of the categories and explain their reasoning. Under each category, list student responses. Tell students that they will revisit this list at the end of the lesson and evaluate their classifications. (Pencil lead is carbon, an element; the metal around the eraser is steel, a mixture of iron, carbon, and other metals; pure rubber for the eraser is a compound, however, most latex products are mixtures of many compounds.)

• Refer students to the periodic table in the Student Handbook (or one displayed in the classroom, if available). Ask, Have you ever used a periodic table before? What do you know about it? Allow students to share what they know about the periodic table.

Explore and Explain

• Have students examine Figure 1 on page 211 of the Student Book. Use the

information in the Science Background to explain how elements are named and how element symbols are assigned. Have students find the locations of gold (Au), silver (Ag), and lead (Pb) on the table. Ask students to try to guess the name of some other elements in the table.

• Direct students’ attention to Figure 2 on page 211 of the student book. Make sure they understand that water is a compound, with each water molecule composed of the elements hydrogen and oxygen. The chemical bond between the hydrogen and oxygen atoms is split by the electric current. Have students find the locations of hydrogen (H) and oxygen (O) on the periodic table.

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Try This: Element Scavenger Hunt

Skills: Performing, Observing, Analyzing, Communicating

Purpose: To identify elements found in household objects and school samples and to

recognize patterns in the arrangement of the elements on a periodic table

Equipment and Materials (per student or group): element samples from school (e.g.,

magnesium, sulfur, silicon) and home (e.g., copper, iron, nickel, aluminum, tin, silver, gold, zinc, carbon); large periodic table (or paper squares, each with an element name written on it)

Student Safety

• Be sure that the elements used are not toxic or otherwise hazardous. Elements that

are in common use, such as coinage metals or the components of air, are assumed to be safe.

Notes:

• Students may require help in determining what elements make up certain materials in their samples. For example, brass items look like copper. Steel is mostly iron but contains small amounts of other elements. Make sure students know the difference between a compound and a mixture and do not use compounds in this activity. Point out that the samples are mainly one specific element, but small amounts of other elements probably are present.

• Have students collect small element samples that will be easy to place on the periodic

table. For example, an iron nail will work better than an iron skillet for this activity.

Suggested Answers:

A. Answers will vary. Of the elements that would be safe for students to handle,

magnesium and sulfur, for example, would need special storage due to flammability. Magnesium lies in the second column and sulfur in the sixteenth column.

B. Some elements used to make coins and jewellery include copper, nickel, zinc, gold, silver, and platinum. These metals lie in columns three through twelve.

C. The elements with a metallic appearance are aluminum, which is in the thirteenth column, lead, which is in the fourteenth column, and the elements in columns to left of column thirteen.

D. The nonmetallic elements lie in the upper right corner of the periodic table in columns thirteen through eighteen.

E. Some elements appear to be both metallic and nonmetallic. These elements lie along a diagonal from the top of column thirteen to the bottom of column sixteen

F. The gases may include oxygen, nitrogen, argon and helium, all of which lie in the upper right corner of the periodic table. This shows that nonmetallic elements may exist as gases under normal conditions, but metallic elements will not.

• Have students read the section, Metals and Non-Metals. Afterward, have volunteers

name the properties of each kind of element. Then have them predict the properties of metalloids. (Examples: a metalloid could be shiny but a poor conductor; or a good conductor, malleable, but dull and powdery. If possible, have them check their predictions with a chemical handbook or on the Internet.)

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• Have students complete BLM 6.1-1: Periodic Table Concept Map independently.

• Have students complete Citizen Action: Recycle Your Cellphone, Save a Gorilla Citizen Action: Recycle Your Cellphone, Save a Gorilla

Purpose: To explore ways to encourage cellphone recycling in the school and

community.

Notes:

• Lead a discussion about recycling cellphones. Ask, Have you ever tried to recycle a cellphone? Where did you take it? What probably happened to your old phone after you dropped it off? Point out that cellphone companies often donate used cellphones

to people who need them but cannot afford to buy them. For example, a cellphone might be programmed so that it can be used just for outgoing calls and then donated to a homeless or abused person who needs the phone for safety.

• Encourage students to write to their cellphone companies to promote the reuse of older cellphones. Some cellphone companies will not provide service to outdated phones.

• Ask students how many older, unused cellphones are in their homes. Make a tally chart on the board. Students might be surprised at the number of unused and potentially recyclable cellphones could be collect from just one class.

Extend and Assess

• Check understanding by listing the symbols for the elements contained in several simple compounds. For example, list H and O for water, and Na and Cl for table salt. Have students make statements that relate the compound, the elements, and the type of elements.. (Sample answers: The compound, water, contains the non-metals hydrogen and oxygen. Table salt contains the metal sodium and the non-metal chlorine.) Allow students to refer to a periodic table showing the element names. • To connect the material in this section with the next section, explain that in the next

section, students will examine the properties of sample elements to identify which ones are metals and which ones are non-metals. Ask, Which properties of metals could you use to identify them? (sample answer: conductivity, shininess)

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Check Your Learning Suggested Answers

1. Of the substances given, tin, chromium, arsenic, and nickel are the elements; only they can be found on the periodic table.

2. An element is a substance that cannot be broken down in to simpler substances by physical or chemical means. A compound is a pure substance that consists of two or more elements that are chemically joined.

3. The white powder cannot be an element because heating has broken it down into simpler substances.

4. This line divides the metallic elements on its left from the non-metallic elements on its right. 5. There are more metallic elements than non-metallic elements.

6. Metals are shiny when polished, have good electrical and thermal conductivity, and can be worked into new shapes without shattering (malleable and ductile).

7. Non-metals have a dull appearance, are poor electrical and thermal conductors, and are brittle.

8. Answers may vary:

Metals Non-metals (a) copper conducts electricity (b) oxygen is a gas under normal

conditions

(c) gold can be flattened by hammering (d) helium’s symbol is located in the upper right corner of the periodic table

(g) sodium is soft and shiny (e) a briquette of carbon shatters when struck

(h) lithium’s symbol is located in the first column of the periodic table

(f) sulfur is a dull yellow powder

9. (a) Copper and aluminum can be worked into new shapes and are good conductors of thermal energy.

(b) Silver and gold can be worked into new shapes and are resistant to corrosion. (c) Argon is a poor conductor of thermal energy.

10. (a) Carbon is a non-metallic solid at room temperature with a relatively high melting point and can exist as a black solid (graphite) or a transparent crystal (diamond). (b) Carbon is a better conductor of thermal energy and electricity than typical non-metals.

• Visual/spatial learners may benefit from creating their own periodic table. The construction of this table should help students get their own perspective of how the table is arranged. Encourage students to create their table in a large form (e.g., a poster, so they can add notes and sketches to elements)

• Bodily/kinesthetic learners may benefit from making a “human periodic table” by arranging classmates as elements on the floor. Make sure students use name tags to designate which element they represent. The name tags can include atomic number, atomic mass, and so on.

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• Verbal/linguistic learners might benefit from listening and reading aloud parts of this lesson. Pair auditory and verbal learners and have them choose the parts of the lesson they wish to review or study. Have the verbal learners read, while the auditory learners listen, ask questions, and take notes.

• Encourage musical/rhythmic learners to write and perform a chant or rap song about a lesson topic. Possible topics include elements and their symbols, properties of metals and non-metals, and the environmental effects of human exploitation of elements. Have students perform their songs for the class.

• Allow interpersonal learners to work together to write summaries of key lesson topics. Have them read their summaries to one another and discuss any differences. If questions arise that students cannot answer, discuss them as a class.

ENGLISH LANGUAGE LEARNERS

• Tell English language learners that the prefix non- means “the opposite of.” Make

sure they know the meaning of opposite by giving examples: black/white, hot/cold,

etc. Explain, then, that the opposite of a metal is a non-metal, which will have the opposite characteristics. Give examples of several different properties of metals and ask students to name the opposites of those properties. (sample answers:

conductive—non-conductive; shiny—dull, or non-shiny; ductile—non-ductile).

UNIT TASK

Skills used in recognizing the physical and chemical properties of elements and compounds can be applied to the Unit Task.

ART CONNECTION

Many metals in the central part of the periodic table form brightly-coloured compounds. These compounds are sometimes used as paint pigments. For example, copper and cobalt are found in certain green pigments. Have students research common paint pigments and find out which of these metals are found in them.

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6.2 Conduct an Investigation Become a Metal Detective Time 60–90 minutes Skills Questioning Predicting Performing Observing Analyzing Evaluating Communicating

Equipment and Materials per student: eye protection lab apron per group: well tray magnet balance

low-voltage conductivity apparatus fine steel wool

element samples

Literacy Resources TK

Assessment Resources

Assessment Rubric 5: Conduct an Investigation Assessment Summary 5: Conduct an Investigation Self-Assessment Checklist 1: Conduct an Investigation

Skills Handbook 2. Scientific Tools and Equipment Skills Handbook 3. Scientific Inquiry Skills

Nelson Science Perspectives 9 website

Maddin, Robert, The Beginning of the Use of Metals and Alloys, The MIT Press, 1988

Johnson, D.A., Metals and Chemical Change, Royal Society of Chemistry, 2002

ExamView® Test Bank

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• demonstrate scientific investigation skills (related to both inquiry and research) in the four areas of skills (initiating and planning, performing and recording, analyzing and interpreting, and communicating)

• formulate scientific questions about observed relationships, ideas, problems, and/or issues, make predictions, and/or formulate hypotheses to focus inquiries or research • conduct inquiries, controlling some variables, adapting or extending procedures as

required, and using standard equipment and materials safely, accurately, and effectively, to collect observations and data

• analyze and interpret qualitative and/or quantitative data to determine whether the evidence supports or refutes the initial prediction or hypothesis, identifying possible sources of error, bias, or uncertainty

• draw conclusions based on inquiry results and research findings, and justify their conclusions

• communicate ideas, plans, procedures, results, and conclusions orally, in writing, and/or in electronic presentations, using appropriate language and a variety of formats

• conduct an inquiry to identify the physical and chemical properties of common elements and compounds (e.g., magnesium sulfate, water, carbon, copper II sulfate)

• describe the characteristic physical and chemical properties of common elements and compounds (e.g., aluminum is a good conductor of heat; copper reacts to moist air by developing a greenish surface of copper carbonate; sodium carbonate is a white, odourless powder that dissolves in water; water has unique physical properties that allow it to support life)

Key Concepts

• Metals and non-metals have characteristic physical properties.

• make testable predictions and give reasons to support them

• conduct an investigation, record and analyze the results, and draw conclusions • determine whether an element is a metal or a non-metal by testing and observing its

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SCIENCE BACKGROUND Chemical Properties

• Although physical properties are used to classify elements as metals or non-metals in this activity, chemical properties could also have been used. However, chemical properties are less universal than physical properties, so classification would have been more complicated.

• Chemical properties are based on how readily an element reacts with other elements. In general, metals increase in reactivity the closer they are to the left side of the periodic table. With the exception of the noble gases, non-metals usually are more reactive the closer they are to the right side of the periodic table.

• One test to identify most metals would be to add an acid to each element sample. If bubbles show that a chemical reaction occurs, the element is a metal. Active metals such as sodium react with acid to form hydrogen gas and a salt. On the other hand, if the sample shows no reaction, the element could be a non-metal, or it could be one of the metals, such as copper, that does not react with an acid. How do you know which metals react with acids? A reactivity series is a list of common metals and hydrogen is shown below. The left-most metal in the series is the most reactive, and reactivity decreases the farther to the right in the series a metal is located.

<=== Most reactive Least reactive ===>

K Ba Ca Na Mg Al Mn Zn Fe Ni Sn Pb H Cu Ag Hg Pt Any metal to the left of hydrogen in the series will react with an acid. Metals to the right of hydrogen in the series do not react with acids.

• Another partial test for metals would be the presence of oxides. Although oxides exist for both metals and non-metals, certain metals react more readily with oxygen than non-metals. Students should be familiar with rusty iron and the white coating of aluminum oxide that appears on aluminum.

• There are exceptions to just about any general property used to classify metals and non-metals. For example, as students will discover in Section 8, graphite, a form of carbon, is a conductor, even though it is a non-metal. For this reason, classification is usually based on several different tests.

TEACHING NOTES

• Make sure students wear eye protection and lab aprons.

• Remind students to wash their hands with soap and water after they finish testing their samples.

• When testing for conductivity, be sure all contacts are secure. If a connection is not complete, the circuit will be broken, and the element sample will test negative for conductivity.

• Advise students that they should rub each element sample with a small piece of the steel wool before testing for conductivity. This process may remove any coating that formed on the sample from a reaction between the element and another substance in the environment.

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Testable Question

Students will test several element samples and classify each one as a metal or a non-metal. Ask, What are some characteristic properties of metals? (sample answers:

conductivity, lustre, malleability, ductility, solid) What are some characteristic

properties of non-metals? (sample answers: non-conductor; if a solid, dull in appearance;

brittle; many are gases) Which of these properties are easy to test for in the laboratory?

(sample answers: luster, malleability, conductivity)

Hypothesis/Prediction

Students will be familiar with many of the elements and will have an idea whether they are metals or non-metals. Do not allow students to look at or touch the samples at this point; they should make their predictions from the names or symbols of the elements (and/or from their positions on the periodic table). If students are allowed to observe the samples, their observations might influence their predictions. (sample predictions: Mg, Cr, Fe, Ni, Cu, Ag, Au, Zn, Al, and Sn are metals. C and S are non-metals. Si has properties of both metals and non-metals.)

Experimental Design

• Point out that the tests can be done in any order. However, any non-metal sample will probably shatter when testing for malleability, so that test should be done last.

• Stations can be set up to test for malleability, density, magnetism, and electrical conductivity. Testing colour and lustre requires simple observations that can be made at any time. A set of element samples can be given to each group or left at each station.

Equipment and Materials

• Almost any set of solid elements can be used as samples, but be sure there are at least two metals and two non-metals. Do not use any gases, as students will not be able to test the properties of a gas. Also, do not use any element that is potentially hazardous. • You might want to provide small hammers and towels for students to use while

checking malleability. Have them wrap the sample in the towel and hit it with the hammer.

• If well trays are not available, element samples can be placed on labeled index cards or other pieces of paper.

• If a more exact measurement of density is desired, provide graduated cylinders and water so that students can measure the volume of samples.

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Procedure

• When students copy Table 1, they should include one row for each element sample. Remind them that the tests can be done in any order, except the test for malleability, so they can be in any order in the table.

• If element samples are not similar in size, density will be difficult to compare. For more accurate data for density, students can use a graduated cylinder to measure volume by water displacement. Density can then be calculated by dividing mass (measured by using the balance) by volume.

• Keep element samples that are intact for later use.

• Emphasize that some elements might be irritating to skin, so students should thoroughly wash their hands after handling the samples.

Analyze and Evaluate

(a) Metallic elements behaved alike in many ways, as did non-metallic elements, but the metallic elements shared different properties than the non-metallic elements.

(b) Answers will vary.

(c) The reports should clearly state conclusions that relate directly to the testable question. Students should cite specific observations to defend their conclusions. (d) Sample answer: It was difficult to judge density because the samples were not the

same size.

(e) Sample answer: Using a balance to measure mass and a graduated cylinder to measure volume directly (powders) or by water displacement (solids) would make it possible to calculate density values.

Apply and Extend

(f) Answers will vary depending on the metals provided. Magnetism, for example, would be a good distinguishing property for subgroups because metals that are similar in luster and conductivity can differ greatly in magnetism.

(g) (i) Copper is a good electrical conductor.

(ii) Aluminum is lightweight (relatively low density) and can be worked into thin sheets.

(iii) Iron is a magnetic material and will react to Earth’s magnetic field.

(iv) Silicon has an electrical conductivity between that of typical metals and non-metals, allowing it to be laced with other elements like arsenic or germanium to make tiny circuit elements.

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• Encourage bodily/kinesthetic learners and visual/spatial learners to help others in their groups—students who might have more difficulty with the actual testing.

Bodily/kinesthetic learners can demonstrate the physical steps of the procedure, while visual/spatial learners can show and describe differences in the elements’ properties. • Ask a bodily/kinesthetic learner and a logical/mathematical learner to team up and

perform a sample density calculation for the rest of the class. The calculation should include measuring both mass and volume—using the correct units—and dividing mass by volume. The volunteers should demonstrate and explain how to measure volume by water displacement (subtracting the volume of water in a graduated cylinder from the sum of the volume of the water and the sample to find the volume of the sample).

• If possible, allow intrapersonal learners to work alone, doing the tests by themselves. Have them keep lists of questions that arise, and encourage them to ask you or other students for help.

• Encourage English language learners to make flash cards for the properties they test. They can write the name of a property on one side of a card and its description on the opposite side. Additional flash cards can be made for important ideas and concepts in other activities in the chapter.

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6.3 Perform an Activity

Properties of Household Chemicals Time 60–90 minutes Skills Questioning Planning Controlling Variables Performing Observing Analyzing Evaluating Communicating

Equipment and Materials per student: eye protection lab apron per group: well plate balance graduated cylinder hot plate test tubes test tube racks beakers

glass stirring rods thermometer scoopulas

Bunsen burner

tongs

conductivity apparatus

household substances: table salt, sugar, flour, candle wax, toothpaste, sand, etc.

water

Literacy Resources Assessment Resources

Assessment Rubric 8: Design Your Own Investigation Assessment Summary 8: Design Your Own Investigation Self-Assessment Checklist 4: Design Your Own Investigation

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BLM 6.3-1: Recording Sheet

Skills Handbook 3. Scientific Inquiry Skills Nelson Science Perspectives 9 website

Gizmo: Mystery Powder Analysis

Palma, Robert J., Ph.D. and Mark Espenscheid, The Complete Guide to Household Chemicals, Prometheus Books, 1995

Selinger, Benjamin Klaus, Chemistry in the Marketplace, Harcourt Brace, 1998

ExamView® Test Bank

Nelson Science Perspectives 9 website www.science.nelson.com

• demonstrate scientific investigation skills (related to both inquiry and research) in the four areas of skills

• apply knowledge and understanding of safe practices and procedures when planning investigations, with the aid of appropriate support materials

• conduct inquiries, controlling some variables, adapting or extending procedures as required, and using standard equipment and materials safely, accurately, and effectively, to collect observations and data

• analyse and interpret qualitative and/or quantitative data to determine whether the evidence supports or refutes the initial prediction or hypothesis, identifying possible sources of error, bias, or uncertainty

• communicate ideas, plans, procedures, results, and conclusions orally, in writing, and/or in electronic presentations, using appropriate language and a variety of formats

• assess the usefulness of and/or the hazards associated with common elements or compounds in terms of their physical and chemical properties

• conduct an inquiry to identify the physical and chemical properties of common elements and compounds

• plan and conduct an inquiry into the properties of common substances found in the laboratory or used in everyday life, and distinguish the substances by their physical and chemical properties

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Key Concepts

• Metals and non-metals have characteristic physical properties

• Elements can be both beneficial and harmful to humans and to the environment

Look for evidence that students can • perform laboratory procedures safely

• design a procedure to determine the physical and chemical properties of common household substances

• make accurate observations and record data accurately • relate the properties of substances to their uses

• communicate the results of a scientific activity

SCIENCE BACKGROUND Mixtures

• Something described as a “material” or a “chemical” can be either a pure substance or a mixture. A pure substance is either an element or a compound (two or more

elements that are chemically joined). A mixture is two or more pure substances that are combined, but not chemically. Some household chemicals, such as sugar and salt, are pure substances (in these cases compounds) because they have the same chemical makeup throughout. However, most household chemicals are mixtures.

• The fact that the components of a mixture keep their properties makes mixtures especially useful in household products. For example, in toothpaste, one component is small pieces of a hard material that serves as an abrasive. Fluorides protect the

enamel on teeth. Other materials make teeth whiter and freshen breath. No single compound could do all these things. Cleaners are also mixtures. Water is an important component of most cleaners. Soap or detergent removes dirt and grease. Other

ingredients might kill microorganisms or make the cleaner smell better. The properties of the cleaner are the sum of the properties of its components.

Conductivity

• Some materials do not conduct electricity when they are dry but do conduct when they are melted or dissolved in water. For an electric current to pass through a material, charged particles must be able to move from one place to another. (A metal is a conductor because electrons are free to move through it. A solution is a conductor due to the migration of its ions..

• Ionic compounds, such as table salt, do not conduct a current when they are dry, but their water solutions will conduct a current. In a solid, ions are not free to move. In a water solution or when the compound melts, the compound dissociates and ions can move from one place to another.

• Molecular compounds, such as sugar, are made up of neutral molecules. As a result, they cannot conduct electricity as solids, liquids or in solution.

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TEACHING NOTES Student Safety

Review the following precautions with students. You can also refer students to Skills Handbook1. Safe Science for a review of safety procedures and precautions.

o Be careful not to touch any hot pieces of equipment or hot materials. o Wear eye protection to protect against splatters of hot materials and

household chemicals.

o When you plug the hot plate into the electric socket, make sure everything is dry.

o When you unplug the hot plate, do not pull on the cord; pull on the plug itself.

• Be sure students understand the difference between reacting with water and dissolving in water. When a material reacts with water, some evidence of chemical reaction occurs, such as a change in temperature or the creation of bubbles. When a material dissolves in water, it just breaks up into its smallest particles, which mix evenly with the water particles. No chemical change occurs during dissolving.

• Provide students with appropriate instructions for disposing the household chemicals that are used in the activity. Explain which materials can be thrown out in the trash can, which can be poured down the drain with plenty of water, and which should be saved for later use.

• Require students to submit written plans for the activity for approval. Make sure that each plan is practical and can be carried out in the time allotted.

Purpose

• This activity will give students an opportunity to develop methods of investigating physical and chemical properties of some common household materials.

Equipment and Materials

• Students can use BLM 6.3-1: Recording Sheet to record their observations.

• To make sure the class finishes in a timely fashion, set up stations with the equipment and materials beforehand. Set up enough stations so that students can work in teams of at most four students each.

• Choose household chemicals that are safe to touch and do not have or produce dangerous fumes. There should be at least one chemical that is combustible, but none that are flammable. (Any material that burns is combustible. Flammable materials burst into flame at a lower flash point and can be considered potentially hazardous.) • Choose at least one household chemical that will show a positive result for each of

the tests. For example, baking powder reacts with water, as shown by the appearance of bubbles.

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Procedure

• Teams should work together to create written procedures for the activity. The procedures can be written out in full, outlined, or take on some alternate form (see Differentiated Instruction below).

• Each team of students should review the steps of their procedure beforehand and assign tasks to each team member. Encourage them to rotate through the tasks, so that everyone gains experience manipulating the substances, performing the tests, and recording the data.

• Advise students that they will not be able to determine all the properties for all the chemicals. For example, they can show that candle wax has a relatively low melting point, but the melting point of salt is so high that they will not be able to melt it with the Bunsen burner.

• Remind students that the properties of substances are not dependent on the size of the sample. For example, the melting point of a small piece of candle wax is the same as the melting point of a larger piece of the same wax.

Analyze and Evaluate

(a) Answers will vary. Tests of physical properties should test for color, hardness, solubility in water, electrical conductivity, melting point, and density. Each of these properties can be measured without changing the identity of the substance.

(b) Answers will vary. Tests of chemical properties should test for combustibility and reaction with water. Each of these properties is related to how a given substance reacts with other substances.

(c) Answers will vary. Sample answer: Melting points were difficult to determine

because materials would sometimes burn before melting or, if they did melt, there was no way to measure the temperature reliably.

(d) Answers will vary. Sample answer: An instrument especially designed for measuring melting points should be used.

(e) Answers will vary, but should include specific references to observations students made. For example, students could describe how solubility in water distinguishes between salt and sand or how combustibility distinguishes between candle wax and baking soda.

Apply and Extend

(f) Answers will vary depending on students’ background knowledge.

(g) You would be safer holding sugar because if you dropped it into the water, it would not increase the electrical conductivity of the puddle, whereas salt would.

(h) The wax has a low melting point and the molten wax can be poured into molds to make candles of many sizes and shapes.

(i) The sand does not melt or decompose chemically when heated to cooking temperatures.

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• Students with different learning styles may approach the design of the activity differently. Logical/mathematical learners may write out steps in full or make outlines. Visual/spatial learners may wish to sketch out steps with captioned diagrams. Interpersonal and verbal/linguistic learners may use oral procedures, but make sure that these students at least have some kind of written outline they can refer to.

• Mathematical/logical learners can extend this activity by determining and comparing the properties of different types or brands of the same kind of household substance. For example, they might choose to check the properties of several brands of

toothpaste or of several types of toothpaste made by the same manufacturer.

Similarly, they could determine and compare the properties of different types of flour (e.g., white, whole-wheat, rice, and tapioca).

• Encourage verbal/linguistic students to write a lab report for the activity. The report should describe the testing procedure used by the students, the results they obtained, and any problems they encountered or conclusions they drew. They might want to enlist visual learners to illustrate their reports.

• Mathematical/logical learners may benefit from quantifying the results of some of the tests, creating tables or graphs and providing detailed explanations of their

calculations. For example, they may want to create a bar graph comparing the melting points of the substances. They can also diagram the steps or calculations used to determine densities of the substances, and then create a table to compare the different densities. For materials that dissolve in water, students can measure the maximum mass of each substance that will dissolve in a certain amount of water and determine the solubility.

• English learners may need help in designing procedures for this activity. Encourage students to write out steps for the procedure using simple imperative sentences. For example, for solubility tests students might write: Step 1: Pour 100 mL of water into each beaker. Step 2: Add 1 scoopful of substance 1. Step 3: Stir until substance dissolves. Step 4: Observe: is any substance left in the beaker? Step 5: If no, 1 more scoopful to beaker. And so on.

At Home

Encourage students to describe the activity to one of their parents, siblings, or relatives at home. Have them give examples of several household chemicals that were tested,

explaining how the uses of the chemicals are related to the substances’ chemical and physical properties.

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6.4 Patterns in the Periodic Table Time 45–60 minutes Vocabulary chemical family alkali metal

alkaline earth metal noble gas halogen period Skills Researching Communicating Evaluating Performing Observing Analyzing

Equipment and Materials per student:

handouts of puzzles A and B

Literacy Resources TK

Assessment Resources

Assessment Rubric 1: Knowledge and Understanding Assessment Summary 1: Knowledge and Understanding

BLM 6.4-1: Find Out About Cesium BLM 6.4-2: Parts of the Periodic Table

Skills Handbook 4. Research Skills Nelson Science Perspectives 9 website

Gordin, Michael D., A Well-ordered Thing: Dmitrii Mendeleev And The Shadow Of The Periodic Table, Basic Books, 2004

Nechaev, I.; Jenkins, G. W.; and Van Loon, Borin, Chemical Elements: The Exciting Story of Their Discovery and of the Great Scientists Who Found Them, Parkwest

Publications, 1997

Chemistry Comes Alive video collection from the Journal of Chemical Education. ExamView® Test Bank

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• demonstrate scientific investigation skills (related to both inquiry and research) in the four areas of skills

• identify and describe a variety of careers related to the fields of science under study, and identify scientists, including Canadians, who have made contributions to those fields

• demonstrate an understanding of the properties of common elements and compounds, and of the organization of elements in the periodic table

• identify and locate print, electronic, and human sources that are relevant to research questions

• select, organize, and record relevant information on research topics from various sources, including electronic, print, and/or human sources, using recommended formats and an accepted form of academic documentation

Career Exploration

• identify and describe a variety of careers related to the fields of science under study and the education and training necessary for these careers

• identify scientists, including Canadians, who have made a contribution to the fields of science under study

• assess the usefulness of and/or the hazards associated with common elements or compounds in terms of their physical and chemical properties

• use appropriate terminology related to atoms, elements, and compounds, including, but not limited to: boiling point, mixtures, particle theory, pure substances, and viscosity

• compare and contrast the physical properties of elements within a group and between groups in the periodic table

• identify and use the symbols for common elements and the formulae for common compounds

Key Concepts

• Metals and non-metals have characteristic physical properties.

• Elements are organiazed according to their atomic number and electron arrangement on the periodic table.

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• recognize the characteristic properties of common families on the periodic table • name some of the chemical families on the periodic table

• distinguish between a period and a family on the periodic table • locate elements on the periodic table

• understand how Mendeleev used the properties of elements to organize them in the periodic table

SCIENCE BACKGROUND Organizing Elements

• Before Mendeleev created his periodic table, scientists made several notable attempts to organize the elements. Although these early organizational attempts did not

succeed—none showed the remarkable insights of Mendeleev’s table—they did show that patterns could be found in the properties of elements.

• In the early 1800s, Johann Wolfgang Döbereiner, a German chemist, noticed certain relationships among small groups of elements. For example, he noticed that the mass of a sodium atom was approximately the mean of the mass of an atom of lithium and the mass of an atom of potassium. He also noticed the same pattern in fluorine, chlorine, and bromine atoms. Because these relationships each dealt with three kinds of atoms, these sets of atoms became known as triads.

• John Newlands, an English chemist, proposed another method of classification just five years before Mendeleev published his periodic table. Newlands proposed a “law of octaves,” which stated that elements repeated properties every eighth element when they were arranged in order of increasing atomic mass. Newlands’s classification method was not widely accepted because it did not work for all

elements, but it did demonstrate that the properties of elements repeated periodically. • The German chemist Lothar Meyer made advances in the organization of elements

that were quite similar to that of Mendeleev—and at approximately the same time. However, Mendeleev’s breakthrough became the accepted method of organizing elements because he published his table first, he demonstrated its usefulness, and he predicted locations on his table of yet undiscovered elements.

• Although Mendeleev’s periodic table is the basis of the current organization of elements, it contained one important error. When elements are listed in order of increasing atomic mass, there are some elements that do not seem to fit into their families according to their properties. For example, cobalt seems to be in nickel’s column, and vice versa. This problem was addressed by the English chemist Henry Moseley in the early 1900s. Moseley discovered that if the elements are listed in order of increasing atomic number instead of increasing atomic mass, the elements

that had seemed out of place would move to new families that matched their properties. Mendeleev’s periodic table, with Moseley’s adjustment, is the basis for our current periodic table.

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• Students may believe that all elements commonly occur in nature as free elements.

Clarify

• Because they react so readily with other elements, most metals (with the

exception of gold and silver) and halogens do not occur or rarely occur in nature as free elements. They are found only as components of compounds.

• At the end of the class, ask, Why can’t you find elements such pure lithium, pure potassium, and pure fluorine in nature? Students should recognize that these elements

belong to families that are highly reactive, and thus are only found in nature as part of compounds.

TEACHING NOTES Engage

• Engage students’ interest by asking, How would you group the following animals: bluejay, rabbit, butterfly, squirrel, eagle, grasshopper, dog, cardinal, beetle?

Students should recognize that the animals fall into three distinct groups – birds, mammals, insects. What makes the members of the group similar? Students should

mention various attributes: size, feathers, fur, ability to fly and so on. Some of the attributes will be the same for all members of a group and some will be different, for example, not all insects are the same size, though they may tend to be smaller than birds or mammals. Relate their classification of animals to the classification of elements. Elements in a group share properties, such as colour, texture, solubility, conductivity, and reactivity, but they can also be different in important ways (e.g., mass, melting point).

• Also review the word periodic with students. Ask, What does the word periodic mean? (That something repeats in a regular pattern.) What are some periodic events in your everyday life? (sample answers: seasons, days of the week, piano lessons,

meals, holidays)

• Show students videoclips of elements and their properties. Many are available online or through commercial products, such as the Chemistry Comes Alive video

collection.

Explore and Explain

• Have students examine Figure 1 on page 220 of the Student Book. Encourage them to become familiar with the names of the colour-coded groups of elements. Explain that the elements in each group have similar properties. For example, elements in the blue family, alkali metals, all share similar properties, as do the elements in the green group, the alkaline earth metals. Emphasize that hydrogen is considered to be in a family of its own—it is not a part of any other family. Tell students that the rare earth elements are not discussed in this chapter. Ask, How many different groupings of elements are there in the periodic table? (Sample answer: 8 groupings: hydrogen,

alkali metals, alkaline earth metals, transition metals, non-metals (in white), halogens, noble gases, and rare earth metals.)

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• Have students complete BLM 6.4-1: Find Out About Cesium independently.

• Direct students’ attention to Figure 6 on page 222 of the Student Book. Explain that the common halogens that are not gases at room temperature vaporize easily. Students can see reddish-brown bromine vapors above the liquid bromine in the middle flask. If the iodine were in a closed flask, the space above the solid iodine would soon be filled with purple iodine vapor. Solid iodine undergoes sublimation,

changing its state directly from solid to gas.

• Discuss the section, History of the Periodic Table. Emphasize that Mendeleev’s key

insight was to arrange elements with similar properties in columns as well as rows.

Ask, Why was this a breakthrough? Students should recognize that suddenly the

elements had a real pattern. They got heavier as you moved from left to right, but the elements in each column, such as lithium and potassium, shared very similar

properties.

• Have students complete Research This:The Periodic Table is Evolving! Research This: The Periodic Table is Evolving!

Skills: Researching, Communicating, Evaluating

Purpose: To investigate a newly discovered element and the process by which elements

are included in the periodic table

Notes:

• Show students a periodic table from about ten years ago. Ask, How has period 7 changed since this old periodic table was published? (More elements have been

discovered, and more have been given official names.)

• As an extension, have some students also research officially-named elements in period 7. Ask them to compare the amount of information available for these elements with the amount of information available for elements with temporary, three-letter symbols.

A. Student answers will vary depending on which element is chosen.

B. The elements in period 7 are synthetic and can only be made literally a few atoms at a time; moreover, these atoms are often unstable and break down. Thus observable samples of these elements have not been prepared.

C. The ultimate authority is the International Union of Pure and Applied Chemistry. D. Answers will vary. Typical answer: I think the process is fair because competing

groups of scientists cannot be objective in deciding what name to give an element. The IUPAC helps to keep the naming processing fair and free of bias.

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• Have students complete Try This: Solving the Puzzle Periodically. Try This: Solving the Puzzle Periodically

Skills: Performing, Observing, Analyzing, Communicating

Purpose: To organize “elements” by properties and to infer the properties of a missing

“element”

Equipment and Materials (per student): handouts of puzzles A and B Notes:

• Suggest to students that they might want to note the criteria they use to organize their puzzle pieces so that they can better justify their final arrangements.

• Emphasize that any arrangement of the pieces is acceptable if it can be justified according to patterns in the pieces’ properties.

A. Students shared experiences will vary.

Extend and Assess

• To conclude the section, refer to the classroom periodic table (or to Figure 1 on page 220 of the Student Book), indicating the chemical families studied in this lesson. Together with students, construct a table on the board describing key families like the sample below. Have students copy the finished tables in their notebooks.

Group Members Key properties Found in

alkali metals Li, Na, K,

Rb, Cs, Fr shiny, silvery, soft, highly reactive, rarely pure elements

table salt, baking soda

halogens F, Cl, Br, I, At

usually gases, highly reactive, non-metals

swimming pools, disinfectant

• As an extension, have students investigate the properties of the transition metals and determine why these elements are grouped together. Challenge them to relate the properties of these elements to their common uses (as structural materials). • Have students complete BLM 6.4-2: Parts of the Periodic Table independently.

Check Your Learning Suggested Answers

1. (a) Incorrect. Elements listed in rows on the periodic table are in the same period.

(b) Incorrect. Elements in the same column of the periodic table exhibit similar

chemical properties. (c) Correct.

(d) Correct. 2. (a) halogens

(b) alkaline earth metals (c) alkali metals