Denton Independent School District / Overview



METAL, NONMETAL, OR METALLOID LABObjective: To observe physical and chemical properties of a set of elements and classify the elements according to those properties.Background Information: 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, or changing, 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 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 seven elements will be investigated, including color, luster, form, malleability, reaction with acid 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:Elements, two small pieces of each: Aluminum, Carbon, Copper, Magnesium, Silicon, Sulfur.Acetic Acid (Vinegar)PipetHammer or other hard, solid objectNailSpatula or ForcepsChemplateConductivity ApparatusPeriodic Table Piece of white paperSafety Precautions: Avoid contact of all chemicals with eyes and all body tissues. Wear chemical splash goggles and a chemical-resistant apron. Wash hands thoroughly with soap and water before leaving the laboratory.PROCEDURE:Using a periodic table, determine the chemical symbol for each of the seven elements to be tested in this laboratory and record it on your data table.Place a piece of while 8 ?” x 11” paper on the lab table and place the chemplate on top of the paper. Place two small pieces of each element into separate wells in the chemplate. Be sure to remember which element you put in each chemplate, or test one at a time. Do not touch any of the elements with your hands! Use a spatula or forceps to obtain each sample. 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.Observe and record the luster of each element in the Data Table. Is the sample lustrous and shiny, slightly shiny, or dull?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? Avoid breathing any vapors directly. Instead of smelling a sample directly, waft the vapors from the sample toward your nose! 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.Use the conductivity apparatus to test the conductivity of the seven 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 does not light, the material is a nonconductor of electricity. Record your results in the Data Table. Avoid touching the electrodes with your hands—an electric shock may result!Determine the reactivity with acid of each sample by adding one pipetful (about 2-3 mL) of Acetic Acid to each well in the chemplate. 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. Observe each substance for approximately 3-5 minutes and record your results in the Data Table.10.Dispose of the used samples into the waste container provided by the teacher. Rinse out the chemplate with water for the next lab group.Teacher’s NotesPre-Lab Preparation:Decide whether to have a central location for the element samples and have students go to that location to obtain the samples needed, or have a sample of each element at each lab station. The following preparation of the element samples must be done prior to the lab.Copper: Cut the ?” wide metal strips into small pieces (approximately 1/8” x ?”) using heavy duty scissors or metal cutters.Magnesium: Cut the ribbon into small strips (approximately ?” 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 (about ?” 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.Sulfur, Aluminum: These elements can be placed out for the lab as is. 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.Tips:Iodine’s properties in the table should be completed by the teacher to show how the data collection table works. Fill in iodine’s information for the class since iodine is toxic. Do not use Iodine in class!Allow 2 to 3 50-minute class periods to complete this lab.To do the electrical conductivity part of the lab, try using the Flinn Conductivity Meter (catalog no. AP1493) If only one meter is available, perform this part as a teacher demo. If no meters are available, consider making your own conductivity tester using small LEDs, wiring and a battery. If no conductivity test is performed, provide the results to the students.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 students to search the internet or the library. Have each group teach the other groups their findings.If students need help identifying the type of element (metal, nonmetal, metalloid), have them specifically look at luster, malleability, and conductivity. Chemicals: Aluminum (metal, shot, Al, A.W. 26.982)Carbon (Charcoal, block, C, A.W. 12.01)Copper (metal, strips, .010” thick, 6” long x ?”, Cu, A.W. 63.546)Magnesium (metal, ribbon, Mg, A.W. 24.31)Silicon (metal, lumps, laboratory grade, Si. A.W. 28.09)Sulfur (roll, lump, laboratory grade, S, A.W. 32.066)Conclusion: Answer the following questions in complete sentences in the form of a paragraph.What was the purpose of today’s lab?Which elements were metals? What properties did they have in common?Which elements were nonmetals? What properties did they have in common?Which element was a metalloid? What properties did the metalloid have in common with the metals?What properties did the metalloid have in common with the nonmetals?If we tested calcium, would it have properties more similar to magnesium or carbon? Explain your answer.What was the most interesting thing you observed in the lab?Conclusion: Answer the following questions in complete sentences in the form of a paragraph.What was the purpose of today’s lab?Which elements were metals? What properties did they have in common?Which elements were nonmetals? What properties did they have in common?Which element was a metalloid? What properties did the metalloid have in common with the metals?What properties did the metalloid have in common with the nonmetals?If we tested calcium, would it have properties more similar to magnesium or carbon? Explain your answer.What was the most interesting thing you observed in the lab?Possible Answers To Conclusion Questions:What was the purpose of today’s lab? To observe the physical and chemical properties of a set of elements and determine if the elements were metals, nonmetals or metalloids.Which elements were metals? What properties did they have in common? Aluminum, copper and magnesium. They were shiny, malleable and conducted electricity. Magnesium and Aluminum reacted with the acid.Which elements were nonmetals? What properties did they have in common? Carbon, iodine and sulfur. They were not really shiny, they were brittle and shattered, they did not react with acid and they did not conduct electricity.Which element was a metalloid? Silicon. What properties did the metalloid have in common with the metals? It was shiny like the metals and conducted electricity even though it was a weaker conductor than the metals.What properties did the metalloid have in common with the nonmetals? It was brittle and did not react with acid.If we tested calcium, would it have properties more similar to magnesium or carbon? Explain your answer. It would be more similar to magnesium because they are both metals and metals have similar properties.What was the most interesting thing you observed in the lab? Answers will vary. ................
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