Materials Included In Kit

Additional Materials Required

Prelab Preparation

The element samples should be set out on the materials table in labeled beakers. The following preparation of the element samples must be done prior to the lab.

• Copper, Zinc—Cut the ½"-wide metal strips into small pieces (approximately ⅛" x ½" using standard, heavy-duty scissors or metal cutters.
• Magnesium—Cut the ribbon into small strips (approximately ½"- or 1"-long pieces) using scissors.
• Carbon, Silicon—These elements come in large blocks or lumps and need to be broken up into small chunks of approximately 0.2 to 0.5 grams (approximately ¼" pieces). This may be accomplished by placing the element in a zipper lock or heavy-duty bag and tapping the sample with a hammer. Remember to break the samples into small chunks rather than into powders.
• Iodine, Sulfur, Aluminum—These elements can be placed out for the lab as is. Remind students to use a spatula to obtain the iodine crystals, since the iodine vapors are intensely irritating to eyes, skin and mucous membranes. Consider covering the beaker of iodine with a watchglass. Sulfur has a strong rotten-egg odor. Warn students not to touch the sulfur with their hands as the odor is not easily washed away, even with soap and water.

Safety Precautions

Perform this lab activity in a well-ventilated laboratory. Iodine is toxic by ingestion and inhalation; it is corrosive to the skin, eyes and the respiratory tract; avoid inhalation of iodine vapors by keeping the iodine bottle covered throughout the lab. Hydrochloric acid solution is corrosive to eyes and skin. Cupric chloride solution is toxic if ingested. Avoid contact of all chemicals with eyes and all body tissues. Wear chemical splash goggles, chemical-resistant gloves and a chemical-resistant apron. Please review current Safety Data Sheets for additional safety, handling and disposal information.

Disposal

Please consult your current Flinn Scientific Catalog/Reference Manual for general guidelines and specific procedures, and review all federal, state and local regulations that may apply, before proceeding. Extra unused materials from this kit can be saved and reused for later labs. Dispose of the acid solutions by neutralizing and flushing down the drain according to Flinn Suggested Disposal Method #24b. Cupric chloride solution can be flushed down the drain according to Flinn Suggested Disposal Method #26b. Solid samples should be disposed of in the solid waste disposal according to Flinn Suggested Disposal Method #26a.

Teacher Tips

• Enough materials are provided in this kit for 30 students working in pairs or for 15 groups of students. This lab can reasonably be completed in one 50-minute lab period with the post-lab questions and discussion completed the following day.
• The Background section contains general information about metals, nonmetals and metalloids found in standard textbooks. Decide whether or not you want to provide this page to the students, as it contains the answers, making this lab more of a dry lab.
• Eight test tubes are provided for each group. If additional tubes are available, provide each group with 16 tubes so students can start both chemical reactions in Part 2 and watch the progress of both while recording observations.
• The electrical conductivity portion of this lab should be done if conductivity meters are available. An excellent option is the portable and sensitive Flinn Conductivity Meter (Catalog No. AP1493). If only one meter is available, perform this part as a teacher demonstration. If no meters are available, consider devising your own “conductivity tester” using small LEDs, wiring, and a battery. If no conductivity test is performed, provide the results to the students.
• Lab mat, if available, is a great option to use for this lab rather than the white piece of paper. Lab mat (Catalog No. SE265) can be cut to any size pieces, is absorbent, can be easily labeled with the element names, and provides for easy cleanup.
• Warn students not to dump the solutions from the test tubes into the sink as the solids may fall in and clog up the drain. Instead, provide a liquid waste beaker.
• The chemical tests (Part 2) of HCl and CuCl₂ with iodine may confuse students because the iodine is slightly soluble in aqueous solutions. Therefore, the solutions may become yellow or darker from the dissolving iodine. This does not, however, indicate any chemical reaction with the reagents.
• Students may question why the symbol for elemental iodine is I2 rather than just I. Iodine is a diatomic molecule, meaning that each molecule of iodine contains two atoms of iodine.
• As an extension, you may wish to have each group research the everyday uses of one of the elements used in this lab. Advise student groups to search the Internet or the library. Have each group teach the other groups of their findings.
• To view more samples of elements, consider purchasing the Flinn Chemical Element Set (Catalog No. AP1128).

Sample Data

See Teacher PDF.

Answers to Questions

1. Review the data gathered for the eight elements. Sort the eight elements into groups, based on similarities and differences in their physical and chemical properties. From the information provided in the Background section, classify each group as metals, nonmetals or metalloids.

   Students will most likely sort the elements into groups as follows.

   Group x—Metals—aluminum, copper, magnesium, zinc
   Group y—Nonmetals—carbon, iodine, sulfur
   Group z—Metalloid—silicon

2. Are there any inconsistencies within the groups you made? Do any elements seem to have properties of both groups? Which? Explain.

   Yes, there are some inconsistencies. Copper does not react with acid or cupric chloride like the other metals (copper is a less reactive metal); however, other properties of copper are consistent with the metals. Silicon seems to have some properties of each group. It is gray and shiny and conducts electricity, consistent with the metals. Yet it is brittle and shows no reaction with either the acid or the cupric chloride, like the nonmetals.

3. Look at the location on the periodic table of each of the eight elements tested in this lab. How do the properties of these elements compare to their general position on the periodic table? Make generalizations about the position of the metals, nonmetals, and metalloids on the periodic table.

   The metals are located in the middle and on the left side of the periodic table (left of the zigzag line). The nonmetals are located on the right side of the periodic table (right of the zigzag line). The metalloids are located on either side of the zigzag line (with the exception of aluminum, which is classified as a metal).

4. Predict the physical and chemical properties of the following elements which were not tested in this lab—selenium, calcium and cobalt.

   Selenium would most likely have nonmetallic properties—dull and brittle, a nonconductor of electricity and would not show a reaction with acid or cupric chloride. Calcium and cobalt would most likely have metallic properties—silver/gray and shiny, malleable, conductors of electricity and would show some reaction with acid and cupric chloride.

Teacher Handouts

11899_Teacher1.pdf

Introduction

Explore the physical and chemical properties of eight elements with the goal of classifying them as metals, nonmetals or metalloids.

Concepts

• Metals
• Nonmetals
• Metalloids

Background

Elements have unique physical and chemical properties, which make them useful for specific purposes in our everyday world. All known elements can be classified as metals, nonmetals or metalloids according to the substance’s specific physical and chemical properties. Physical properties are properties that can be observed without changing the identity of a substance, and chemical properties are properties that are observed while altering the identity of the substance involved.

Metals and nonmetals are separated by the zigzag or stair-step line on the periodic table. Most elements are classified as metals, which are located from the center to the left side of the zigzag line. Metals are elements that are usually silver-gray in color, with the exception of copper and gold. All metals are solid at room temperature except mercury, which is a liquid. Metals have a lustrous or shiny appearance and reflect light when polished. They can be bent or hammered flat (malleable), can be drawn into wire (ductile), are good conductors of heat and electricity, usually show reaction with acids, and generally have high melting points (many above 800 °C).

Nonmetals are found to the right of the zigzag line on the periodic table. There are many fewer nonmetals than metals. Nonmetals are usually dull in appearance and do not reflect light. Many are brittle, and therefore cannot be hammered into sheets. Nonmetals are poor conductors of electricity and heat, show little or no reaction with acids, and generally have low melting points. At room temperature, nonmetals can exist as either solids or gases, with the exception of bromine, which is a liquid.

Elements found along both sides of the zigzag line are called metalloids, with the exception of aluminum. Metalloids are elements that show properties of both metals and nonmetals. Metalloids are not good conductors of electricity; however, when mixed with small amounts of other elements, the conductivity of metalloids increases.

In this laboratory activity, a variety of physical and chemical properties of eight elements will be investigated, including color, luster, form, malleability, reaction with hydrochloric acid solution, reaction with cupric chloride solution, and electrical conductivity. The elements will then be classified as metals, nonmetals, or metalloids. It is important to note that although elements can be categorized and generalizations can be made, each element has its own unique properties. Thus there are many exceptions to the rules for classifying elements.

Materials

Safety Precautions

Perform this lab activity in a well-ventilated laboratory. Iodine is toxic by ingestion and inhalation; it is corrosive to the skin, eyes and the respiratory tract; avoid inhalation of iodine vapors by keeping the iodine bottle covered throughout the lab. Hydrochloric acid solution is corrosive to eyes and skin. Cupric chloride solution is toxic if ingested. Avoid contact of all chemicals with eyes and all body tissues. Wear chemical splash goggles, chemical-resistant gloves and a chemical-resistant apron. Wash hands thoroughly with soap and water before leaving the laboratory.

Procedure

Prelab Preparation

1. Using a periodic table, determine the chemical symbol for each of the eight elements to be tested in this laboratory. Fill in the chemical symbol for each element on the data table.
2. Place a piece of white 8½" x 11" paper on the lab table. Use a pencil or pen to draw lines, dividing the paper into eight squares (four squares across, two squares down). Label each square with the chemical symbol of one of the eight elements to be tested.
3. Obtain eight test tubes. Place the tubes in a test tube rack and label each tube with the chemical symbol of one of the eight elements.
4. Take the test tube rack to the chemical table and place two small pieces (or a few crystals) of the appropriate element in each tube. (Note: Do not touch any of the elements with your hands, especially the iodine. Use a spatula or forceps to obtain each sample; avoid all skin contact with iodine and avoid breathing its vapors.)
5. At your lab bench, empty the samples onto the piece of paper by inverting each test tube over the appropriately-labeled square.

6. Observe and record the color of each element in the data table. Is the sample silver, gray, colored, etc.…? Be very specific in recording observations.
7. Observe and record the luster of each element in the data table. Is the sample lustrous and shiny, slightly shiny, dull?
8. Record any other physical properties that are observed about each element in the data table. Be specific in your observations. What form is the sample in? Is the sample crystalline, flaky, rough, smooth, flat and plate-like, rocky, in strips? Is there any odor or are any vapors given off? (Note: Avoid breathing any vapors directly. Instead of smelling a sample directly, waft the vapors from the sample toward your nose.)
9. Determine whether each element is malleable or brittle. To do this, position a nail on the sample and gently tap the nail with a hard, solid object (such as a small hammer, piece of wood, small book, stapler). A material is malleable if it flattens or bends without shattering. A sample is brittle if it shatters or cracks into pieces when struck. Record your results in the data table.
10. (Optional) If a conductivity apparatus is available, use it to test the conductivity of the eight samples. Touch both electrodes to the element being tested, being sure that the electrodes are not touching each other. If the bulb lights brightly, the sample has allowed electricity to flow through it and is a strong electrical conductor. If the bulb lights dimly, the sample is a weak electrical conductor. If the bulb fails to light, the material is a nonconductor of electricity. Record your results in the data table. (Caution: Avoid touching the electrodes with your hands—an electric shock may result.)

11. Use a spatula or forceps to place one small piece (or a few crystals) of each of the eight elements into the appropriately labeled test tube in the test tube rack. (Note: Use the samples you emptied onto your sheet of paper.)
12. Determine the reactivity with acid of each sample by adding one pipetful (about 1 mL) of 1 M hydrochloric acid to each tube. (Note: Evidence for a chemical reaction may be the formation of gas bubbles and/or discoloration on the surface of the element. Some reactions may be slow to start—be patient.)
13. Observe each tube for approximately 3–5 minutes and record results in the data table.
14. Decant the liquid from the tubes into the liquid waste container provided by your teacher and dispose of the solids in the solid waste disposal. Rinse out the tubes with water for the next step.
15. Use a spatula or forceps to place another small piece (or a few crystals) of each of the eight elements into the appropriately-labeled test tube in the test tube rack.
16. Determine the reactivity with cupric chloride solution of each sample by adding one pipetful (about 1 mL) of 0.1 M cupric chloride solution to each tube.
17. Observe each tube for approximately 3–5 minutes and record results in the data table.
18. Decant the liquid from the tubes into the liquid waste container provided by your teacher. Dispose of the solids in the solid waste disposal. Rinse out the tubes with water for the next lab group.

Student Worksheet PDF

11899_Student1.pdf