YOUR BODY'S BUILDING BLOCKS
Grades 10-12

This lesson is a continuation of the Periodic Table. Previous classes may have focused on the historical development of the Periodic Table. Several properties and characteristics could have been discussed as well. The lesson will focus on the building blocks of our bodies, chemical elements. The video, Mind Your Own Body: What's A Body?, will increase the students' awareness on how the elements affect their lives. Through a hands-on approach, students will measure the presence of iron in the body.

Mind Your Own Body: What's A Body? (#1)

Students will be able to:

• Identify elements' symbols.
• Identify elements present in the body.
• Identify the source of several elements.
• Explain the result of element deficiencies.

• iron III thiocyanate
• potassium thiocyanate
• hydrochloric acid
• distilled water
• crucible cup
• clay triangle
• ring stand
• bunsen burner
• test tubes
• filter paper
• funnel
• stopper
• food items:
  • raisins
  • parsley
  • rice
  • broccoli

Divide the class into groups of 4 to 5 students. Ask the students: Why is the table is called the Periodic Table? (Response: Repeating characteristics and properties.) Allow students to identify these similarities among the elements.

Ask the students: Why is the table of elements important? (Response: Everything is made up of atoms.) Explain the make-up of water and air.

Share with the students the 13 elements which make up the human body. Write the symbol, not the name, of each element on the chalkboard. Include the percentage of each element present in the body. (A transparency can also be made of this chart.)



O (Oxygen) 65% S (Sulphur) 0.25%

C (Carbon) 18% Na (Sodium) 0.15%

H (Hydrogen) 10% Cl (Chlorine) 0.15%

N (Nitrogen) 3% Mg (Magnesium) 0.05%

Ca (Calcium) 2% Fe (Iron) 0.004%

P (Phosphorus) 1.1% I (Iodine) 0.0004%

K (Potassium) 0.35%



Ask the students to name each element (O -- Oxygen, C -- Carbon, H -- Hydrogen, N -- Nitrogen, etc.). Depending on the amount of time you wish to devote to this activity, a competitive activity involving groups of students could be conducted.

To give the students a specific responsibility while viewing, tell them: Observe the video segment carefully and be prepared to answer the following questions (contained on a worksheet or on the chalkboard):

1. Name three major elements in the human body.
2. What makes up a molecule?
3. Why are molecules important?
4. Explain how the elements contribute to human cells.

PLAY
tape where the music video starts.

STOP
tape when the announcer says, "Cells are the building blocks for all living things." (5 minutes)

After viewing the tape, again depending on the amount of time you wish to spend, you may either ask the students to discuss their answers and record them on the chalkboard, or you may collect their worksheets with the brief answers to the four questions.

Classroom Discussion
Chemistry is the study of matter, and matter is made up of the elements. Each element is important for life and a deficiency in the 13 elements in the human body will result in sickness.

List several elements and their sources as well as the result of a deficiency of these elements. (Use either the chalkboard or transparencies for the information listed below.)


Elements Important for : Source Deficiency

Sodium body fluid salted food cramps
Potassium cells / fluid fruit / milk weakness
Chlorine body fluid salted food cramps
Calcium bone / teeth dairy cramps
Phosphorus bone / teeth dairy weakness
Magnesium nerve / muscle grain / diarrhea
leafy vegetables
Iron red blood cells raisins / eggs / anemia
meat
Flouride bone water dental

Day 2
Lab: Detecting Iron in Food Samples
Read and explain the discussion and procedure.

Discussion
Iron is an essential mineral needed for life because it is important for red blood cells. The human body is made up of 0.004% iron. If one is lacking iron, a sickness called anemia occurs. If this occurs, iron pills are taken or foods rich in iron are increased in the diet. Iron produces an ion called ferrous which is absorbed and used in the human body. In this experiment you will determine which of the foods you test have the most iron, by observing the red color of iron III thiocyanate, Fe(CN)3, formed in the food filtrate produced. The darker the red color of the filtrate in the test tube the more iron the food contains.

Procedure
1. Place a small amount of food in a crucible (either raisins, parsley, rice, or broccoli).

2. Place the crucible onto a clay triangle on a ring stand and remove the water, heating with a bunsen burner.

3. Heat the food until it turns into ash.

4. Place the ash into a medium test tube.

5. Add 5 ml. of hydrochloric acid (HCl) to the test tube.

6. Stopper the tube and shake vigorously for about 1 minute.

7. Add 5 ml. of distilled water to the test tube.

8. Filter the contents of the test tube into a larger test tube.

9. Add 5 ml. of potassium thiocyanate (KSCN) solution to the test tube.

10. Place a stopper into the test tube and swirl gently.

11. Add two drops of ferric chloride (iron III chloride), FeCl3, to the test tube and swirl.

12. Save the test tube to compare it with the other food filtrates you will prepare.

13. Repeat the above procedure with the other food samples and compare your results.

Conclusion
The material listed below may be transcribed onto student worksheets.

1. List the 4 foods in order, starting from the one with the most iron content to the one with the least iron content.







2. Balance the equations for the reactions that take place when iron is present in foods.



_____ Fe + _____ HCl -- _____ FeCl3 + _____ H2


_____ FeCl3 + _____ KSCN -- _____ Fe(SCN)3 + _____ KCl


3. List other minerals you can think of that are found in foods.

1
Language Arts:
Write a two-page paper on how chemicals modify the food we eat.

2
Home Economics:
Develop a food pyramid by substituting the elements obtained from each specific food group.

3
Health:
Invite a dietitian to discuss the advantages and disadvantages of vitamins and minerals in our diet.

Visit a health food store to examine nutritional foods.

4
Social Studies:
Invite a pharmacist to discuss the history of pharmacy and the origin of several elements.

Master Teacher: Rowland V. Bynum