Unit 2Matter

Properties and Change

Century High SchoolChemistry 2013-14

Name _______________________________________________

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Unit 2 General Chemistry Standards

I. I can describe the basic structure of the atom.

A. I can compare and contrast the mass and charges of the components of an atom (protons, neutrons and electrons).

B. I can identify the locations of the protons, neutrons and electrons in an atom.

II. I can use the atomic mass and atomic number of an atom to determine its number of protons, neutrons and electrons.

A. I can identify the atomic number and atomic mass of an atom using its chemical symbol and the periodic table.

B. I can use the “isotope symbol” of an atom to determine the number of protons, neutrons and electrons.

III. I can explain the difference between isotopes of an atom.

A. I can determine the average atomic mass of an element if given the percentage amount and masses of each of its isotopes.

B. I can compare and contrast the number of neutrons, protons and electrons for different isotopes of an atom.

IV. I can determine the mass percentage of each component in a mixture.

A. I can use lab data to determine the masses of each component in a mixture.

I can determine the percentage by mass of each component in a mixture using that da

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Unit 2 – Assignments

ACTIVITY SCORE

Chemical and Physical Change ______________

Making and Recording Observations ______________

Elements, Compounds, and Mixtures ______________

The Law of Conservation of Matter ______________

Filtration ______________

Chromatography ______________

Separation of a Mixture ______________

Baseballium ______________

Isotopic Pennies ______________

Periodic Table Practice ______________

Quizzes ______________

______________

Test ______________

TOTAL SCORE FOR UNIT ______________

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Important Abbreviations (You will probably use most of these in biology)

Hydrogen (H) Magnesium (Mg) Nickel (N)Helium (He) Aluminum (Al) Copper (Cu)Lithium (Li) Silicon (Si) Zinc (Zn)Beryllium (Be Phosphorus (P) Silver (Ag)Boron (B) Sulfur (S) Iodine (I)Carbon ( C) Argon (Ar) Barium (Ba)Nitrogen (N) Potassium (K) Gold (Au)Oxygen (O) Calcium (Ca) Mercury (Hg)Fluorine (F) Manganese (Mn) Chlorine (Cl)Neon (Ne) Iron (Fe)Sodium (Na) Cobalt (Co)

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Unit 2 - Matter

Substances

States of Matter

Solids

Liquids

Gases

Physical Properties of Matter

Can be observed or measured without changing the sample’s composition

Chemical Properties of Matter

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Observing Properties of Matter

Changes in Matter

Physical Changes

Chemical Changes

Conservation of Mass

Mixtures of Matter

Mixtures

Types of mixtures

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Heterogeneous mixture

Homogenous mixtures (Solutions)

Separating Mixtures

Filtration

Distillation

Crystallization

Sublimation

Chromatography

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Chemical and Physical Change

Problem: What kinds of changes can matter undergo?

Materials: hard candy, mortar and pestle, test tube, cork stopper, Bunsen burner, deflagrating spoon, wooden splint copper strip, magnesium ribbon, crucible tongs sugar.

Procedure:

1. Examine a piece of hard candy. Notice its color, taste, and appearance. What does hard candy contain?

2. Grind up some hard candy in the mortar. (Rub in a circular motion with the pestle.) Do not hammer because you may break the mortar. What kind of change has occurred? Explain your answer.

3. Drop some of the candy into a clean test tube that is half full of water. Cork the tube and shake it up. Has the dissolving of the candy changed it into something else? What kind of a change is this? Explain your answer.

4. Heat some (1 – 2 ml) of the sugar water in an evaporating dish. What do you observe? What is does the left over material in the dish look like?

5. Using tongs, heat each of the following in a Bunsen flame. What kind of a change takes place?

a. A wooden splint ____________________________________b. A strip of copper ____________________________________c. A strip of magnesium ribbon. ____________________________________

Caution: You should not look directly at the bright light of the burning magnesium.

Conclusions

1. Define a chemical change and define a physical change.

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Making and Recording Observations

One important skill in the use of the scientific method is the skill of making and communicating observation. In this activity you will mix some chemical in the laboratory and record your observations. Look carefully at the materials before and after mixing and use all your senses. You will first write some initial notes of the observations, and then describe them in more detail.

At this point in the class it is not necessary for you to know what the chemicals are so they will just be labeled with letters: A, B, C, D, E. You will mix each chemical with each other, one at a time. One way to record your lab results is to make out a chart. Use a full sheet of paper and make five columns and label them: A, B, C, D, E. Then along the left side make five rows. Label these with the letters but in reverse order. This is because it is not necessary to mix a chemical with itself and once a chemical has been mixed (A + B) you don’t need to repeat that combination (B + A). Make sure that each “box” has enough space to record your observations. You must have your table done before you will start the lab.

In the lab, test each combination using your plastic dropper plate. When testing two combinations of chemicals, just add 2-3 drops of each chemical into a spot (well) on the plate. Note carefully the appearance of each chemical before mixing and then after. If you feel there has been change you may write “no reaction” as your observation. When testing the metal “E” with the other chemicals place a piece of “E” into a well and then add enough of the other chemical to cover it. You may want to wait 2-3 minutes for each case to see if any delayed reaction occurs or if there are further changes that occur.

When you have finished, be sure to remove the un-reacted metal E with tweezers and discard in the waste containers. Then rinse out the test plates with tap water and dry before returning to the lab drawer or table top.

Follow-up Questions

1. After you are done with your observations, check your results with some other groups. Explain using complete sentences what you find and why there may be differences.

2. For two of the combinations in which you believe there was a chemical reaction, describe in writing using complete sentences what you observed. Give a good picture of the “before” and “after”.

3. What kinds of observations indicate there may have been a chemical reaction?

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Elements, Compounds, and Mixtures

Problem: How can we distinguish elements, compounds and mixtures?

Materials Iron filings, iodine, iron iodide, 3 heat-resistant test tubes, cored for the test tubes, magnet, Bunsen burner, matches, test tube holder, wooden splint

Procedure

1. Add a splint full of iron filings (element) into a test tube and cork the tube.2. Add a splint full of iron iodide (compound) into a second test tube and cork this tube also.3. Repeat this procedure in the third test tube with half a splint full of iron filings and half a splint

full of iodine. Cork the tube.4. Look at the materials in each test tube and describe them below and in your lab report5. Bring a magnet to the bottom of each test tube and move it half way up the side of the test

tube. Record your observations.6. Gently heat your test tubes for no more than one minute. Stop heating as soon as a reaction

starts or after one minute. Record your observations.

Data TableAppearance of the material

Test tube 1

Test tube 2

Test tube 3

Reaction to a MagnetTest tube 1

Test tube 2

Test tube 3

Reaction to HeatTest tube 1

Test tube 2

Test tube 3

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Conclusions

1. How do elements, compounds and mixtures differ?

2. Why did the magnetic property of iron change in the compound?

3. Which element undergoes sublimation?

4. List two other examples of sublimation.

5. Can you depend on appearances to distinguish elements, compounds, and mixtures?

Filtration12

Problem: How can filtration purify water?

Materials: Wooden splint, powdered clay, vegetable oil, garlic powder, 2 test tubes, ink, medicine dropper, funnel, filter paper, Styrofoam cup, gravel, sand, sharpened pencil, 2 beakers, ring stand, ring clamp, ring, clay triangle

Procedure

1. Using a wooden splint, put a pinch of powdered clay and an equal amount of garlic powder into a test tube. Half fill the test tube with water. Add ¼ inch of vegetable oil. Add three drops of ink. Stopper the tube and shake it up. Does the clay dissolve? What happens to the oil? What does the ink do? Is this a solution or a mixture? Why?

2. Support the funnel above a beaker with the ring stand and clay triagle. Hold your finger over the opening of the funnel’s stem and pour the mixture into the funnel. Wait until two liquid layers form. Which liquid is on top?

3. Carefully allow the water to pour into the beaker. Stop the flow with your finger again when the oil is at the end of the stem of the funnel. Collect the oil in a separate beaker.

4. Fold a piece of filter paper into quarters. Grasp three of the quarter together, open the paper to form a cone, and fit it into your funnel. Wet the paper in the funnel.

5. Place the stem of the funnel into a clean test tube in the support rack. Carefully pour the clay-ink-garlic-powder suspension onto the filter paper. Careful not to allow the suspension to reach over the edge of the filter paper.

6. If the filtrate is not clear at first, then filter the suspension again through the same filter paper. What happened to the suspended solids? Is the filtrate clear? Does the filtrate have a color? How does the filtrate smell?

7. Place a fresh piece of filter paper into the funnel. Fill ½ of the filter paper with activated (deodorizing ) charcoal. Filter the suspension again. How does the filtrate look? How does it smell?

8. Place ½ inch of gravel on the bottom of a Styrofoam cup. Cover the gravel with 1 ½ inches of sand. Cover the sand with ½ inch of gravel. Poke three holes through the bottom of the cup with a sharp pencil point. Place the cup on a small beaker. Make another clay-ink suspension and our it over the top gravel. Record your observations. At the end of this exercise, do not pour your sand or gravel into the sink.

9. Are there mixtures which might not be able to be separated by filtering?

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Conclusion

1. How could you change muddy water into clear water?

2. How can odors be removed from water?

3. Why didn’t filtration remove the ink?

4. Explain the process of filtration.

5. Identify the residue and the filtrate.

6. Why does the filtrate become clearer when the filtration is repeated?

7. Why is gravel placed above and below the sand?

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Chromatography Separation

In this experiment we'll use thin layer chromatography paper to analyze black pen ink and compare components of this ink to other colored marker inks.

Materials:

Sharpie Markers Chromatography paper and Solvent (alcohol)Paper Clips Chromatography jars

Hypothesis: Black ink is actually many colors of ink that can be separated using chromatography.

Procedure:

1. Draw a line with a sharpie pen across the bottom of a rectangular piece of chromatography paper.

2. Hang the paper in the chromatography jar.3. Pour alcohol into the jar so it just covers the bottom of the paper.4. Watch the alcohol work it’s way up the paper.5. Remove the paper and dry.6. Measure how far each color went7. Record the colors in your data diagram

Color Distance in mm that it traveled

Conclusion:

1. Which color traveled the farthest? Least?

2. Why and how did the colors separate?

3. What property of the ink caused the color to separate?

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Separation of a Mixture

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Mixtures are a form of matter which contain more than one substance put together and can be physically separated. The parts of a mixture are not bonded together and are not uniform. The amounts and percentages can vary.

The purpose of this activity is to develop a procedure and use it to separate a mixture of iron, salt and sand. Your task is to determine the mass of each part of the mixture and find the mass percentage. The formula is

Mass Percentage (%) = the mass of the part x 100The total mass of the sample

Procedure: With your partner first examine the sample of the mixture. Then discuss what steps will be used to separate the mixture. List all steps in the order you will do them. State clearly what you will do in each step. Explain any measurements that will be made. Include the names of all pieces of equipment needed in your plan. You must have your procedure approved by the teacher before doing the activity.

Data tablePart Mass in grams Mass Percentage

Sand

Salt

Iron

TOTAL100 percent

Separating the Mixture: Use your procedure to separate the mixture and determine the mass of each part. You do not need to turn in each part and you may throw away the parts as you are done.

Conclusion:

1. What happened to the salt? Where did it go?

2. Are there any sources of error in this lab? What?

I. Purpose: What are you trying to do in the lab?

II. Procedure: What steps, actions will you do to separate each part of the sand, salt and iron mixture?

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1. Measure and record the mass of the sample.

2. Use a magnet to pull out the iron. Measure and record the mass of the iron.

3. Add the sample some water, stir to dissolve the salt.

4. Measure and record the mass of the dry paper.

5. Fold the filter and set it up in the funnel with a flask.

6. Filter the sand.

7. Take it out and unfold onto a watch glass. Let it dry overnight.

8. The next day mass the dry filter paper and record.

III. Data Table: Listing each measurement you will do and the units.1. Mass of the total mixture _____________g2. Mass of the iron _____________g3. Mass of the dry filter paper before filtering _____________g4. Mass the dry filter paper the next day _____________g

Analysis

Mass % Iron = Mass of Iron x 100 = Iron % . Total Mass

Mass % Sand = Mass of Sand x 100 = Sand % . Total Mass

Mass % Salt = Mass of Salt x 100 = Salt % . Total Mass

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Baseballium

INTRODUCTIONROCHESTER, MN. – Nuclear chemists, performing basic research on soil found in Minneapolis, Minnesota, have discovered what is believed to be element 120. The researchers have named this element baseballium, derived from the location in Minneapolis where the original discovery was made. It was the erratic behavior of humans (pushing, shoving, shouting, imbibing) that led to the ultimate discovery and research of the element.

Further research of the new element, this reporter was told, will be conducted in more suitable surroundings, namely laboratories in a nearby high school. Student excitement regarding the discovery is running at a fevered pitch. Many chemistry students have generously volunteered their time to help with the follow-up experiments involving the new element.

A reliable source was overheard to say that the first experiments will determine how many isotopes of this element exist. Isotopes are atoms of an element which behave chemically the same, but have slightly different physical properties. One variable property among isotopes is their atomic mass. After finding how many isotopes comprise the element, researchers will look for the atomic mass of each and finally their weighted average, which will become the atomic mass of baseballium.

One unique property of baseballium should make this experiment particularly easy: baseballium atoms are very large. Therefore, sorting the isotopes of this element should be accomplished with very little difficulty. A detailed procedure of the experiment is enclosed. Scientists are expecting a complete, comprehensive summary within the week.

PROCEDURE1. The sample of the baseballium atoms will be distributed to each laboratory group. The

differences between the isotopes is very distinct. Each isotope has a different exterior color.

2. Sort the baseballium atoms into groups according to color, each group representing a different isotope. Count the number of atoms (spheres) in each group and record this number on the data sheet.

3. Weigh each sample of atoms (spheres) and record the mass on the data sheet.

4. Return all atoms to the sample container when you are finished weighing the sample and return the container to the instructor.

Data:

TOTAL NUMBER OF ATOMS IN THE CONTAINER ____________

ISOTOPE BREAKDOWNTYPE OF ISOTOPE No. OF ATOMS MASS OF ATOM SAMPLE

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1. Clear Isotope

2. Red Isotope

3. Green Isotope

4. Blue Isotope

PROCESSING THE DATA

1. Calculate the average mass of a baseballium atom. This average mass is the atomic mass of the element. (total mass/total no. of atoms)

2. Calculate the atomic mass of each isotope. (total weight of isotope/no. of atoms)

Clear __________ Red __________

Green __________ Blue __________

3. Calculate the percent abundance of each isotope. (number of atoms of isotope/total number of atoms)

Clear __________ Red __________

Green __________ Blue __________

5. Chemists use an instrument called a mass spectrometer to determine the percent abundance and relative mass of each isotope in a sample of an element. These values are then used to determine the average mass of all of the isotopes in a sample. The following calculation is performed:

(mass of isotope A)(decimal fraction of isotope A) + (mass of isotope B)(decimal fraction of isotope B) + etc.

(The decimal fraction is just the percent composition expressed as a decimal)

6. Compare your answer for question #1 to your answer to question 5.

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Isotopic Pennies

Purpose: To learn a way in which scientists can determine the relative number of different isotopes present in a sample.

Procedure:1. The teacher will give you a pre-1982 penny, a post-1982 penny, and a container filled with a mixture of 10 pre- and post-1982 pennies with the mass of the empty container. Record that information and the code number of your sealed container.

2. Determine the isotopic composition of the element “coinium.” That is, find the percent of pre-1982 pennies and post-1982 pennies in your container.

Data:A. Code number of film canister __________________B. Mass of empty film canister __________________gC. Mass of pre-1982 penny __________________gD. Mass of post-1982 penny __________________gE. Mass of sealed canister of pennies ___________________gF. Total mass of pennies ___________________g

Calculations:

G. Number of pre-1982 pennies ________H. Number of post-1982 pennies ________I. Percent composition of “Coinium” pre-1982 ________% post-1982 ________%

Questions:

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1. Describe the procedure you used to find the percent composition of “coinium.”

2. What property of the element “coinium” is different in its pre- and post-1982 forms?

3. In what ways is the penny mixture a good analogy or model for actual element isotopes?

b. In what ways is the analogy misleading or incorrect?

5. 140 students participated in a knowledge retrieval session. 25 scored 90 out of 100; 63 scored 80 out of 100; 31 scored 70 out of 100; 15 scored 60 out of 100; 6 scored 50 on the knowledge retrieval session. Determine the average score on this knowledge retrieval session. Show all work.

6. Magnesium consists of three isotopes with masses of 23.98 (78.6%), 24.98 (10.1%), and 25.98 (11.3%). Calculate the average atomic mass of Mg. Show all work.

7. Copper consists of two isotopes, one with a mass of 62.96 and 70.5% abundant. The other isotope has a mass of 64.96. Determine the atomic mass of Cu. Show all work

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Practice with the Periodic Table

Fill in the blanks on this table using the periodic table found above and the abbreviations needed.

Number Element SymbolAtomic Mass

Atomic Number Protons Neutrons Electrons

1 C

2 Oxygen

3 7

4 27.0

5 P

6 Magnesium

7 Mn

8 35.0

9 11

10 30

11 127.0

12 Fe

13 Sulfur

14 20

15 19

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