Chemistry Around Us

Christiana Ichara
Pin Oak Middle School

INTRODUCTION

There are many sayings about teaching as a profession. Some people believe teaching is an art form. Others believe that one has to love teaching in order to make it a lifelong commitment. The latter is true for me. I love to teach, and I want my lessons to be interesting and meaningful to my students. My experiences with different age groups have made this idea of a meaningful and interesting lesson a burning desire for me to accomplish within the confines of the curriculum.

I have taught for many years, in different countries, and at different grade levels. All through these years, the same questions keep coming to mind.

• How can I make my lessons interesting and meaningful to the students?

• What kinds of hands-on- materials would be most useful and effective for the learners to comprehend, considering the enormous amount of materials/activities available to both teachers and students today?

• Is it possible for my students to design experiments, write equations for the chemical reactions, and create molecular descriptions of a future event based on current evidence or past experience?

Based on these experiences, I decided to develop a curriculum that will enable my students to understand the periodic table, elements, and compounds. If everything we see around us is either an element or a compound, then in order to understand the world, as we know it, we have to somehow engender in the students a mode of thought that sees things at that level. When students drink a glass of water for example, do they have a blank spot in their minds when the materials they are devouring are slithering down their little throats or do they see little models of the water molecule, in constant motion of course, in fact in enough motion to be in the liquid phase? And do they see the molecular interactions between the water molecules, with the negative pole of one little molecule attracting the positive pole of another, so much so in some cases that water actually ionizes itself, constantly forming hydronium and hydroxide ions and then just as constantly forming water molecules again depending on the proximity of the molecules? In this curriculum unit, I want to explore how we can create scientifically literate thoughts in the minds of our students and how we can get them thinking at the atomic level.

Learning to see the nano-world, the world of the very small, has never been more necessary than at this particular historical conjunction. With Hollywood making movies about the nanobots, instilling fear of what might certainly prove to be the salvation of our planet, the study of the atom-to-atom interactions must at some point be understood and mastered if we are to have the means to control our destiny. It becomes all the more important for teachers to address this aspect of the human conversation, demystifying and demythologizing the study of the atoms and molecules that make up our material environment.

This year I have been a participant in the Houston Teacher’s Institute (HTI) seminar “Chemistry through the Ages.” In the seminar we have attempted to peer into the discussion of

what the universe is made of, starting with the Greeks—Democritus and his teacher Leucippus, who first proposed in writing that has been preserved, the concept of the atom. It is startling to look back as these incredibly perceptive natural philosophers as they used human reason to try to explain the world they see around them. It is amazing to know that their thinking was not influenced by a science class in school in which the teachers tried to get them to believe in atoms. They just deduced, using logic and their own experience, that the world must be composed of tiny basic particles that cannot be further divided without losing something essential.

This notion was debated, ignored, pondered, and finally in the 1600’s, experimented with when John Dalton finally said, “Darn. My laboratory experiments tell me that Democritus was right on the money.” But again, Dalton was experimenting and thinking in a relative scientific void compared to the climate our students are privileged to be immersed in. Later in the early 1900s we find ourselves having to again make a radical leap in our understanding as J. J. Thomsen discovers a disturbingly negative little something (electron) that streams out of the little solid marble that Democritus and Dalton envisioned. Then Rutherford stuns the world when his alpha particles whiz right through the thin gold foil instead of being deflected like Thomsen’s plum pudding would have done if it indeed were plum pudding. Shazzam, we undergo a paradigm shift in our thinking about the atom, as it suddenly becomes mostly empty space, a far cry from what Democritus, Dalton and Thomsen saw. After Bohr got through with that empty space it was divided into distinct energy levels and after de Broglie got through with the electron, it was never in any one spot but was instead a negative cloud with only probabilities to describe it. The atom that our students learn then, is the result of a long process of trial and error, a model that is still being revised and changed but which now explains more neatly the things we see happening in our laboratories. And, seeing things happen in the laboratory that can then be explained using the models is what this unit purports to do.

Students will learn the specific uses of the elements, the dates of their discovery, and the probable physical and chemical changes that may occur when these elements are placed in close proximity to one another. The lessons will be suitable for middle school students, especially the sixth graders. This is the age when children seem to develop a lack of interest in academics, and science in particular. Either that or they suddenly develop inordinate interest in the social aspects of being human so that all else is pushed aside. The objective of this unit is to present lessons on elements, compounds, and chemical reactions that show a relationship amongst these topics in a fun and interesting way. Experimentation with household items that will demonstrate the extent of chemical reactions around us will be explored at a greater length. Making chemical reactions real instead of an abstract concept will be a major focus of this curriculum unit.

UNIT BACKGROUND

Because of the work we did in the HTI seminar with Dr. Scott Perry (University of Houston chemistry professor) studying the developing understanding of chemistry through the ages, I am inspired to help my students investigate the nature of elements, their arrangement in the periodic table, the extent of their abundance, their difference from compounds and mixtures, and their role in chemical reactions.

The students will investigate the year elements were discovered, their uses, and how they are arranged in the periodic table. They will identify some familiar compounds and their constituent elements. This curriculum unit will help my sixth grade students understand the historical development of our knowledge of the elements, how we have learned to understand elements combining to form compounds, and how compounds and elements interact to create the phenomena we witness in our daily lives. The curriculum will also be an excellent tool for any middle school science teacher who is interested in a new and innovative method of teaching physical and chemical changes, chemical reactions, and the discovery of elements. The students will create a data table with the names of the elements, dates of discovery, uses of these elements, and plot a graphical representation of the period that the elements were discovered. The graph will be an additional tool to address different types of learners. Teachers who want to avail themselves of the books cited in the bibliography will find these sources rich in narratives that give life to what could otherwise be dry lists of facts. In the course of the HTI seminar we have read three books in particular which can help teachers develop a more narrative approach to the teaching of chemistry facts. (See bibliography)

One may want to know why it is important to know when these elements were discovered. Today’s students want to accomplish tasks in a fast and easy manner. Anything that takes a while to accomplish is considered to be a waste of time. I see this behavior almost everyday in my laboratory. Students want to know why they should do three trials to obtain a valid result; why can’t they do it once or twice; why do they need three trials per test, always why, why, why? Students need to know the many, many, many years of trials, accidents and lucky guesses that have preceded our current volume of knowledge about the make-up of the universe. The students need to know that some elements such as carbon and sulfur were known and used by ancient civilizations. The Iron Age and the Bronze Age are named for the elements and compounds that helped shaped the events we are taught as history.

In this unit, the students will also use analytical and qualitative skills, inferences and predictions, creativity, and problem-solving skills to investigate elements in each group of the periodic table. The students will work in groups of eight to investigate elements, when they were discovered, their physical and chemical properties, and some common reactions. They will also be able to identify constituent elements from the reactions.

Overview of Elements, the Periodic Table, Compounds, Mixtures, and Chemical Reactions

Elements are found almost everywhere, in the ocean, in the air, the earth, and the body. An element is a pure substance that is made of only one kind of atom. An atom is a tiny structure found in all matter. Matter is anything that has mass and occupies space. Most substances contain many different atoms. Elements contain only one kind of atom. The most abundant element in the air is nitrogen, in the earth is oxygen, and in the body is hydrogen. Elements found in the body are hydrogen, oxygen, carbon, nitrogen, and other trace elements. In the Periodic Table, elements are arranged in horizontal rows and vertical columns. The elements in the horizontal rows are known as periods while the elements in the vertical columns are known as groups or families. The horizontal rows represent electron energy levels, and the vertical columns represent the chemical properties of the elements. Elements are also grouped as metals, non-metals, and metalloids. Metals are elements that have the properties of luster, malleability, ductility, and conductivity. Nonmetals do not have the properties of luster, malleability, ductility, and conductivity. Metalloids are elements that have some properties of both metals and nonmetals. The type of information available from the periodic varies depending on the version; however, each table has the element name, symbol, the atomic number, and the atomic mass. A symbol identifies a single element, the atomic number equals the number of protons, and the mass number equals the number of protons plus neutrons. The number of electrons equals the number of protons. An atom is the smallest unit of an element. It consists of three particles, namely, protons, neutrons, and electrons. The nucleus of the atom is made of protons and neutrons while the electrons move around rapidly in the space outside the nucleus.

Chemists use the periodic table to determine which elements can combine and in what proportions. They also use the periodic table to determine which elements have similar properties. Chemists can use this information to help manufacturers determine how to improve their products and processes. For example, the use of helium instead of hydrogen in dirigibles provides safety.

Two or more elements combine chemically to form a compound. Molecules are two or more atoms joined together by chemical bonds. The atom can be the same element or different elements. If the molecule is a combination of different elements, it is a compound. Carbon dioxide (CO₂) and sodium chloride (NaCl) are compounds, while ozone (O₃) is not. It is a molecular form of the element oxygen.

Mixtures are made of two or more pure substances that are mixed together but not chemically combined. Examples of mixtures are Italian dressing, pizza, and fruit salads. In these examples, the ingredients are mixed together, but they still maintain their separate identity. Mixtures are classified into two groups namely heterogeneous and homogeneous. A heterogeneous mixture means that no two parts are identical, for example, pizza and salad. A homogeneous mixture occurs when different parts appear as one, but are not. Some examples of homogeneous mixtures are milk, stainless steel, and toothpaste. In homogeneous mixtures, particles are mixed together but are not dissolved completely; they are known as colloids. Colloids are larger than ordinary molecules but too small to be seen with ordinary eyes. Most colloids appear cloudy. The table below shows some examples of colloids:

Type of Colloid	Examples
Fog (Liquid in gas)	Clouds
Smoke (Solid in gas)	Smoke
Sol (Solid in a liquid)	Paint
Foam (Gas in a liquid)	Whipped cream
Emulsion (Liquid in a liquid)	Mayonnaise
Gel (Liquid in a solid)	Butter

Chemical reactions take place when bonds between atoms break and form one or more new substances. An equation describes a chemical reaction using symbols and formulas. The reactants are on the left of the equation while the product(s) are written on the right of the equation. Chemicals are reacting if there is evidence such as color change, production of a gas, and odor. New substances are created when chemicals react. A change in temperature indicates that energy is being released or used as new substances are formed. Reactants are chemicals that take part in chemical reactions, while products are the new substances that form as a result of the chemical reactions. An endothermic reaction is a reaction in which energy is absorbed. An endothermic reaction feels cool because heat energy from the hand is absorbed by the reaction. An exothermic reaction is a reaction in which heat energy is released.

A chemical equation may be a synthesis reaction, a decomposition reaction, or a replacement reaction. In a synthesis reaction, two or more substances combine to form a new substance. Synthesis reactions happen around us everyday. When fire burns, rust forms, and silver tarnishes, synthesis reactions have taken place. Burning of a wooden splint is a chemical reaction of a fuel and oxygen. Heat and light are always produced in this synthesis reaction. In decomposition reaction, a compound breaks down to form one or more simpler substances. This reaction occurs everyday, for example, when you take a cap off a bottle of sprite or any other soda, bubbles rise quickly to the top. Carbonic acid breaks down into carbon dioxide and water. Chemical bonds are the forces that hold the different substances of a compound together. These bonds are broken when the attracting forces are broken through the use of energy.

Replacement reactions may be a single replacement reaction or double replacement reaction. A single replacement reaction happens when one element replaces another in a compound while in a double replacement reaction two elements or compounds trade places and a precipitate, water or gas, forms. A precipitate is an insoluble solid formed in the solution.

A chemical reaction is also known as a chemical change. In a chemical change, a new substance is produced. Energy changes always accompany chemical changes. Some examples of chemical changes are:

• Hydrochloric acid reacts with sodium hydroxide to produce a salt, water, and heat.

• Potassium chlorate decomposes to potassium chloride and oxygen gas.

• Iron rusts.

• Milk sours.

• Wood rots.

• Acid on limestone produces carbon dioxide gas.

A physical change involves a change in form while the original substance still exists. Some examples of physical changes are:

• Sodium hydroxide dissolves in water.

• A pellet of sodium is cut in two.

• Liquid is heated and changed into vapor.

• Ice melts.

IMPLEMENTATION STRATEGIES

The students will work in groups to investigate the following:

Elements and the year the elements were discovered, uses of these elements, and the arrangement of elements in the periodic table.

Each group will be given the following names: Group 1 - Alkalis (he Alkali Metal Family – Group 1 Elements), Group 2 – Earth Metals (The Alkaline Earth Metal Family – Group 2), Group 3 – Transitionals (The Transition Elements Family – Group 3- 12), Group 4- The BCNO (The Boron, Carbon, Nitrogen, Oxygen - Group 13- 16), Group 5- Halogens (The Halogen Family – Group 17), Group 6- Nobles (The Noble Gases – Group 18), Group 7 – Lanthanides, Group 8 - Actinides.

The students will make a list of elements and their discovery dates on a table similar to the table shown on Appendix A.

The data on the date of discovery of elements will be used to plot a bar graph that shows how many elements were discovered within a certain period. Is it important for the students to know when elements were discovered? I think it is important because students usually search for an easy route to solve problems; therefore, if they discover through their research that the discovery of elements were not made in a day, maybe they will be more patient during their lab investigations. Every teacher wants to cultivate the right attitude to their students, in this case, the scientific method of investigation and conducting experiments, so knowing when elements were discovered and their uses will add a wealth of knowledge to any middle school students, especially my six graders.

The students will also use a table to group substances into elements, compounds, and mixtures. The table should be similar to the one shown below:

Elements	Compounds	Mixtures
Pure One kind of atom Can be separated in nuclear reactions Examples: Gold (Jewelry) and Aluminum (soda can)	Pure Two or more kinds of atoms chemically combined Can be separated by chemical reactions Examples: beaker of water (Hydrogen and Oxygen) Iodized salt (Sodium and Chlorine) Carbon Dioxide (Carbon and Oxygen)	Not pure Two or more elements or compounds physically combined together Can be separated in physical reactions Examples: Italian Dressing and Dumpling Sauce

The table will also include equations for reactions and structural formulas. The students will use Styrofoam balls and other tools to make molecular structures.

The students will use many sources including books and the Internet to research their elements. Based on their investigations, the students will appreciate the role elements play in our daily lives.

Chemical reactions are the focal point of this unit; therefore, the students will conduct experiments that demonstrate different types of reactions, such as synthesis reactions, replacement reactions, and decomposition reactions, and write equations for the reactions. They should also be able to identify a reaction as exothermic or endothermic. In an endothermic reaction heat is released during the process while heat is absorbed in an endothermic reaction.

The project will end with a collage in which all the groups will work together to create a periodic table with information compiled by individual groups. The collage will be a replica of the periodic table, however, without element names, symbols or atomic numbers. The only data on the table will be the potential uses of the element in today’s world. This will be the highlight of the project because it will involve all the scientists (my students) working together to create a periodic table that is unique, beneficial, and meaningful to them.

Finally, each student will either write a song, a poem, or create a puzzle about the periodic table using the element symbol, picture and any new information that they have discovered during their investigation.

Lesson PlanS:

Lesson One: Discovery of Elements.

Objectives: The students will understand and appreciate the unique nature of elements, the historical development of elements, the arrangement of elements in the periodic table, and how elements play a role in our daily lives.

Materials

Computer

Paper

Pencil

Graph paper

Procedure

1. Provide background information on an element.
   Explain to the students that the periodic table is the most important tool available to scientists especially chemists, because it provides a wide range of information about natural and synthetic elements. At present, there are 92 naturally occurring elements and 23 synthetic elements. These elements are arranged in horizontal rows and vertical columns. The elements in the horizontal rows are called periods while the vertical columns elements are known as groups or families. The horizontal rows represent electron energy level, and the vertical columns represent the chemical properties of the elements. There are 7 periods and 18 groups or families, which are numbered from left to right of the periodic table.

2. Allow the students to draw a table with three columns in their laboratory book. The first column is titled “Element,” the second column “Date of Discovery,” and the third “Use.” (See Appendix A.)

3. Take the students to the library where they can use computers, books and other resources to investigate elements. (See appendix for sample.)

4. After compiling the data, allow the students to plot a bar graph of the date that the elements were discovered.

By the end of lesson one, the students should be able to compile a table of elements, the date of discovery of these elements, uses of the elements, and plot a graph that will demonstrate how many elements were discovered within a given period.

Lesson Two: Chemical Reactions

Objective: To understand chemical reactions using household materials and dilute acids.

In this lesson, chemical reactions will be explored with concrete examples using common substances such as baking soda, salt, baking powder, vinegar, laundry detergent, and chemicals, such as hydrochloric acid, sulfuric acid, and chlorine. The students will have opportunity to discuss, write equations, and make models.

Chemical reactions occur when bonds between atoms break and form one or more new substances. A chemical reaction is described by an equation using symbols and formulas. For example, calcium chloride reacts with sodium bicarbonate (baking soda) to produce calcium bicarbonate and sodium chloride. This is represented by the equation – CaCl₂ + 2 NaHCO₃ -> Ca( HCO₃)_{2 +} 2 NaCl.

A chemical reaction is also known as a chemical change. In a chemical change, a new substance is produced. Energy changes always accompany chemical changes. Some examples of chemical changes are as follows: iron rusts, milk sours, wood rots, potassium chlorate decomposes to potassium chloride and oxygen gas.

A physical change involves a change in form, or phase, the original substance still exists. Some examples of physical change are as follows: sodium hydroxide dissolves in water, heated liquid changes into steam, and ice melts into liquid.

Experiment

Question:

What species are involved in chemical reactions?

Materials:

Distilled white vinegar (5% aqueous solution of acetic acid - HC₂H₃O₂)

Sanded magnesium ribbon (Mg)

Beaker

Graduated cylinder

Stirring rod

Triple beam balance (If using magnesium from a chemical supply store)

Science journal

Procedure:

1. Divide the class into 4 groups.

2. Give each group the above materials.

3. Measure 10mL of vinegar and pour it in a beaker.

4. Drop a piece of freshly sanded magnesium ribbon in the beaker of white vinegar and stir with a stirring rod. (If magnesium from a chemical supply lab is available, use a triple beam balance to measure 5g of magnesium.)

5. Record observation in your science journal. Draw and label the beaker of vinegar and magnesium.

6. Write a chemical equation for this reaction. Label the reactants and the products.

Safety Precaution:

1. Wear safety goggles

2. Do not taste or smell any substance.

3. Wipe spills as they happen.

4. Wash hands at the end of the activity.

Lesson Three: Types of Chemical Reactions

Objective: The students will explore different types of chemical reactions through experimentation.

In this section, the teacher will give the students background information on different types of chemical reactions. The students will be expected to perform simple experiments that demonstrate each type of reaction in this lesson and subsequent lessons.

Different Kinds of Chemical Reactions:

• Synthesis Reaction - Two or more substances combine to form a new substance. Synthesis reactions happen around us everyday. When rust forms or silver tarnishes, synthesis reactions have taken place.

• Decomposition Reactions - A compound breaks down to form one or more simpler substances. This reaction occurs everyday, for example, when a cap is taken off a bottle of sprite or any other soda, bubbles rise quickly to the top. Carbonic acid breaks down into carbon dioxide and water.

Carbonic acid	->	Carbon dioxide	and	Water
(H2CO3) -	->	CO2	+	H20

• Replacement Reactions – It may be a single replacement reaction or double replacement reaction. A single replacement reaction occurs when one element replaces another in a compound, while in a double replacement reaction, two elements or compounds trade places and a precipitate forms. The precipitate may be water or gas.

Experiment One: Synthesis Reactions

Question: What will happen to a silver spoon if submerged in an egg yolk?

Hypothesis: (Allow the students to write their hypothesis.)

Sample hypothesis – If there is a chemical reaction between the silver spoon and egg yolk, then a new substance should form.

Materials:

Egg

Silver spoon

Stop-watch

Beaker

Water

Laboratory notebook

Safety Precautions:

Wear goggles

Do not play with the egg.

Procedure:

1. Separate a yolk from an egg white and placed the yolk in a 100-mL beaker.

2. Place a clean silver spoon in the egg yolk and stir.

3. Allow the spoon to sit in the container for 30 minutes.

4. Remove the spoon in egg yolk, rinse with water, and observe what happened to the spoon.

5. Record observations in your laboratory note book.

Conclusions: Answer the questions in your laboratory notebook.

1. What happened to the spoon in the egg yolk?

2. Was there a chemical reaction? If there was, what caused the chemical reaction?

3. Is it possible to reverse the change? How?

4. Why does silver tarnish if left sitting for a long period of time? Is there sulfur in the air?

5. Write an equation for this reaction.

Experiment Two: Decomposition Reaction

Objective: The students will understand that decomposition reactions involve the breaking down of a compound to form one or more simpler substances.

Background Information:

Give the students an overview of the sugar molecule. Most students might not know that sugar is composed of three different elements with 45 atoms in one simple molecule. (Sugar molecule – C₁₂H₂₂O₁₁) Sugar can be decomposed by heating it.

Question: Does Sugar Break Down into it Constituents Elements When Heated?

Hypothesis: (Allow the students to state the hypothesis)

Materials:

Sugar

Test tube

Metal tong

Hot plate or Bunsen burner

Triple beam balance

Safety Precautions:

1. Do not eat the sugar

2. Use precaution when working with hot plate or Bunsen burner.

Procedure:

1. Measure 5g of sugar and place each 5g of sugar in two identical test tubes.

2. Place test tube A on the test tube rack.

3. Hold test tube B with a metal tong and heat the test tube carefully until the sugar is completely black.

4. Observe test tubes A and B and record your observation.

5. Using a wooden splint, taste the burnt sugar. (Do not shallow it)

Conclusion:

1. Did the change in chemical composition affect the appearance or odor? Is it still sugar?

2. Write a chemical equation for this reaction.

Experiment 3: Single Displacement Reactions

Objective:

The students will perform simple experiments that explain the process of replacement reactions.

Background Information:

Remind the students that replacement reactions may be a single replacement reaction or double replacement reaction. A single replacement reaction occurs when one element replaces another in a compound, while a double replacement reaction occurs when two elements or compounds trade places and a precipitate is formed. The precipitate might be water or gas. A precipitate is a solid in the solution that is not dissolved.

Materials:

3 Molar HCl (Hydrochloric acid) 20% solution

Copper (penny)

Zinc (galvanized nails are coated with zinc)

Magnesium (from a chemical supply store)

3 Test tubes (for each group)

Test tube rack (one for each group)

Goggles

Safety Precautions:

1. Wear goggles.

2. Do not touch the acid.

3. Report any spills to the teacher. Do not attempt to clean the spill!

Procedure:

1. Divide the class into 4 groups.

2. Label the test tubes, A, B, and C. A – Copper, B –zinc, C- magnesium.

3. Measure 10mL of hydrochloric acid into the three test tubes.

4. Drop each metal into their respective test tube and observe.

Conclusion:

1. Did you observe any bubbles in the test tube?

2. Which test tube had more bubbles? Why?

3. In which test tube did you feel a slight warming of the test tube?

4. Write a singe replacement reaction equation for the 3 test tubes.

Lesson Four: Get To Know Your Elements (Gifted &Talented/Pre-Advanced Placement Students)

Objective: The students will work independently to write a detail description of five elements and how they are used today.

This section will be devoted to the detailed discussion of the uses of elements. The students are to use the resources in the library to investigate the uses of their assigned elements. This is mainly for the Gifted and Talented /Pre- Advanced Placement students.

Each student should give a detailed description of at least 10 elements and how they are used today. For example: Helium is used by astronomers to eliminate space noise on their detectors. The students should describe how it works. For example, how do astronomers use helium to eliminate space noise? Helium was used to make the first gas lasers. Today gas lasers are used in bar code scanners. Scuba divers use a mixture of oxygen and helium to breathe. These are some of the uses for helium.

Procedure:

Following a class discussion of the uses of the different elements, the class will construct a periodic table of the elements in which each element is represented by a picture of its use. Chemical symbols will be added to the picture for identification purposes.

Appendix A

Element	Date of Discovery	Use
Phosphorus	1669	-It is used to make produce light, in glow in the dark clocks, watches, and toys. -It is used in television to make the image. -It is used in laundry soaps and other detergents.
Platinum	1700	-It is used to make jewelry. -It is used in refining oil, dental instruments, ceramics, electrical and the electronic industries.
Nickel	1751	-It is used to make coins and nickels. -It is used in magnets, heating elements in toasters and electric ovens. -It is used in rechargeable batteries for calculators, computers, and electric shavers.
Hydrogen	1766	-It is used to make ammonia, fertilizer, margarine and rocket fuel.
Oxygen	1774	-It is used as liquid rocket fuel, makes ozone that protects us from ultraviolet rays from the sun.
Potassium	1807	-It is used in explosives and gunpowder, to make batteries, and liquid soap.
Iodine	1811	-It is used to make photo film, kill germs in small wounds. -Iodine tablets are used to purify water.
Aluminum	1825	-It is used to make doors, screens, and window frames. -It is used to make drink cans, pots, and pans. -Aluminum is used in wires, reflectors, resistors, antennas, and solar mirrors.
Indium	1863	-It is used in transistors and photocells.
Argon	1894	-Argon is used in fluorescent light bulbs.

Appendix B

Definition of Terms

Atom: The smallest unit of an element.

Atomic mass: Equals the number of protons plus neutrons.

Atomic number: Equals the number of protons.

Chemical bonds: Forces that hold atom together in molecules and keep ions in place in solid ionic compounds.

Chemical equation: Is a statement that uses chemical formulas to express the identities and quantities of the substances involved in a chemical or physical change.

Chemical reaction (chemical change): A chemical reaction occurs when bonds between atoms break and form one or more new substances.

Chemical formula: Scientific short way of describing the chemical content of a substance. Number and letters stand for how many and what kinds of atoms are in one molecule of the chemical. For example: In CO₂, the C stands for carbon and the O stands for Oxygen. There are two atoms of oxygen and one atom of hydrogen.

Compound: Two or more elements combined chemically.

Constant: Conditions that an experimenter tries to keep from varying. (The same)

Control: In a simple experiment, there is only one subject or group that gets the experimental treatment. To better judge the results, the experimenter may use a control group or subject. This group does not get the experimental treatment but it is treated in every other way like the experimental subject or group.

Colloids: Homogeneous mixture in which particles are mixed together but are not dissolved.

Decomposition reaction: A compound breaks down to form one or more simpler substances.

Dependent/Responding variable: When the experimenter changes something to observe what happens in an experiment. What he or she changes may cause something else to happen. Therefore, what happens as a result of the change is known as the dependent or responding variable.

Electron: An electron carries a negative charge. Electrons move around rapidly in the space outside the nucleus.

Element: An element is a pure substance that is made of only one kind of atom.

Endothermic reaction: A reaction in which heat energy is absorbed.

Exothermic reaction: A reaction in which energy is released.

Experiment: An investigation made by changing or manipulating things. An experiment is usually planned to answer a specific question, to solve a problem, or to test a statement or hypothesis.

Heterogeneous mixtures: A mixture that has one or more visible boundaries among its components.

Homogeneous mixtures (solution): A mixture that has no visible boundaries among its components.

Hypothesis: A statement that explains what is to be tested, the purpose of an investigation, and what the experimenter intends to prove or disprove.

Independent/Manipulated variable: An experimenter changes something in the experiment to observe what will happen. The something that is changed is the independent or manipulated variable.

Matter: Anything that has mass and occupies space.

Mixtures: Two or more substances that are mixed together but not chemically combined.

Neutron: Protons and neutrons make up the nucleus of an atom. It carries no charge, therefore, is neutral.

Precipitate: An un-dissolved solid in a solution.

Product: A new substance formed in a chemical reaction, the right side of the yield sign in a chemical reaction.

Proton: Protons and neutrons make up the center or nucleus of an atom. The proton carries a positive charge.

Reactants: The materials that react in a chemical equation, substances to the left of the yield sign_.

Solutions: Mixtures in which molecules are dissolved and uniformly dissolved into one another.

Symbol: A symbol identifies a single element.

Variables: In a thing or pattern of things being observed, a change in a dimension or a characteristic, a change in value or quantity.

Appendix C - Answer Key

Lesson Two: Chemical Reactions

Experiment One: Observations

When magnesium is placed in vinegar (vinegar contains 5% aqueous solution of acetic acid – HC₂H₃O₂), a chemical reaction occurs. Bubbles of hydrogen gas are released and the strip of metal forms a new substance called magnesium acetate.

Magnesium and acetic acid are the reactants, while magnesium acetate and hydrogen gas are the products.

Mg + 2C₂H₄O₂ Mg(C₂H₃O₂) + H₂

Magnesium Acetic Magnesium hydrogen

acetate (gas)

Lesson Three:

Experiment One: Synthesis Reaction

Conclusion

1. The spoon turned dark (tarnished).

2. Yes, the silver spoon reacts with the egg yolk that contain trace amount of sulfur. This reaction produced the dark color.

3. Yes, an acid will react with sliver sulfide to reverse the dark color.

4. There are some traces of sulfur in the air because of pollution- this trace element is responsible for the tarnishing of silver wares if left outside for a longtime. Yes, there are traces of sulfur in the air because of pollution.

5. Ag + S Ag₂S

Silver Sulfur Silver sulfide

Experiment Two: Decomposition Reaction

Conclusion

1. Yes, the white powdered sugar turned black. This indicates that the sugar broke down into carbon (the black material in the test tube) and water. The water droplets are on the side of the test tube.

2. No, because the sugar has broken down into its constituent elements and compound which is carbon and water.

3. C₁₂H₂₂O₁₁ + heat 12C + 11H₂O

Sugar Carbon Water

(glucose)

Experiment Three: Single Replacement Reactions

1. Yes

2. No bubbles form in the Beaker A (copper). A reasonable amount of gas is produced in Beak B (Zinc) and while Beaker C (magnesium) produced bubbles of gas. Beaker C feels warm because the reaction of magnesium and hydrochloric acid is an exothermic reaction.

1. Cu + HCl CuCl₂ + H

2. Zn + HCl ZnCl₂ + H

3. Mg + HCl MgCl₂ + H

ANNOTATED BIBLIOGRAPHY

Abbgy, Theodore S. Elements and the Periodic Table. Greensboro, NC: Mark Twain Media/Carson–Dellosa Publishing Company, 2001.
This book gives a detailed description of the modern periodic table, the arrangement of elements in the periodic table, and what things are made of.

Barber, Jacqueline. Chemical Reactions. Lawrence Hall of Science. University of California, Berkeley, 2001.
This book outlines simple experiments that could be used to teach chemical reactions.

Blashfield, Jean F. Sparks of Life – Calcium. Austin, Texas: Raintree Steck–Vaughn Publishing, 1999.
This book provides the basic idea of the element calcium, its uses and functions in the human body.

Farndon, John. Chemicals. New York: Marshall Cavendish Corporation, 2003.
This book provides a detail description of elements, compounds and chemical reactions. The experiments given in the book reinforce an understanding of the topics.

Farndon, John. The Elements--Oxygen. New York: Marshall Cavendish Corporation, 1999.
The history of oxygen and properties of oxygen is discussed extensively in this book.

Fitzgerald, Karen. The Story of Oxygen. New York: A Division of Grolier Publishing, 1996.
This book describes the history of the elements oxygen and its chemistry, how it works and its importance in our everyday activities.

Hill, Petrucci and Perry McGreary. General Chemistry, 4e. Upper Saddle River, New Jersey: Prentice Hall, 2005.
This book provides a detail account of general chemistry with particular reference to elements, their structure and functions.

Knapp, Brian. Hydrogen and the Noble Gases. Danbury, CT: Atlantic Europe Publishing Company Limited, 2000.
This book gives an overview of the periodic table and a detail description of the chemistry of hydrogen that is appropriate for a middle school student.

Knapp, Brian. Sodium and Potassium. Danbury, CT: Atlantic Europe Publishing Company Limited, 2000.
This book provides an overview of chemical reactions with particular reference to sodium and potassium.

Le Couter, Penny and Jay Burreson. Napoleon’s Buttons. New York: Penguin Group Inc., 2004.
This book gives an account of the link between chemistry and nature. It goes on to illustrate how a substance can be both harmful and beneficial depending on the chemical combination and proportion of the reactants.

Newmark, Ann. Chemistry. New York: Dorling Kindersley, 1999.
This book provides in depth discussion of chemistry in nature as well as works of modern alchemist like Ernest Rutherford.

Sparrow, Giles. The Element – Carbon. New York. Marshall Cavendish Corporation, 1999.
This book gives a brief history of the discovery of carbon, the different forms of carbon, and the role carbon plays in the greenhouse effect.

Uehling, Mark D. The Story of Hydrogen. New York: Grolier Publishing, 1995.
This book presents the properties of hydrogen in a story form. It is an interesting resource for any middle school science class.

Uehling, Mark D. The Story of Carbon. New York: Grolier Publishing, 1995.
This book uses favorite children characters to describe the properties of carbon.

Morris, Richard. The Last Sorcerer: The Path From Alchemy to the Periodic Table. Washington D.C.: Joseph Henry Press, 2003.
This book gives the genesis of what we know today as scientific inquiry. Louis Lavoisier performed several experiments that provided lasting and verifiable proof of many chemical theories by measuring, examining and recording data.

Silberberg, Martin. Chemistry: The Molecular Nature of Matter and Change. New York: McGraw Hill Companies Inc., 2003.
This book gives detail examples of major classes of chemical reactions and their molecular structures.

Strathem, Paul. Mendeleyev’s Dream: The Quest for Elements . New York: The Berkley Publishing Group, 2002.
This book outlines the historical perspective in the development of the periodic table. It gives a detail explanation of how politics, and religion affected scientists thought process during the early centuries.

Thomas, Moorman. How to Make Your Science Project Scientific. New York: John Wiley & Sons, Inc. 2002.
This book gives a detail simple explanation on how to conduct a scientific experiment.

Trombley, Linda. Mastering the Periodic Table. Portland, Maine: J. Weston Walch Publisher, 2000.
This book explains the design, uses and complexities of the periodic table.

White, Larry. Water: Simple Experiments for Young Scientists. Brookfield, Connecticut: The Millbrook Press, 1995.
This book provides age appropriate experiments and lessons on the properties of water.

Winter, Mark. Webelements. Sheffield, England. February 1, 2005.
http://www.Webelements.com/webelements/scholar/index.html
This site provides an online periodic table, history of each element, physical properties, electronic configuration, and the structure of each element and their compounds. It also outlines the safety procedures when handling the elements, and uses of these elements.

Wynn, Charles M. and Arthur W. Wiggins. The Five Big Ideas. New York: John Wiley& Sons, Inc.,1997.
This book gives account of the major scientific discovery such as the plate tectonics, tracing the elements roots, the model of an atom, and sorting out elements. (The Periodic Table)