Flinn Hands-On Chemical Element Set

Introduction

Element sets provide the opportunity for chemistry and physical science teachers to instruct in a more hands-on, descriptive manner. All too often students are expected to learn names and symbols for elements that they have never seen. It is not surprising that students sometimes find this task frustrating and difficult. Students will have a better grasp of chemistry if they are able to connect names and symbols with real elements exhibiting real properties.

Background

The element set contains 11 different element samples, including three forms of a metal (copper) and two forms of a non-metal (carbon), for a total of 14 samples. The elements are listed according to their positions on the periodic table (see Figure 1).

Safety Precautions

Nickel is a possible carcinogen and toxic as a dust or fume, but much less hazardous in shot form. Nickel may be irritating to skin and may cause an allergic reaction to sensitized individuals. Magnesium ribbon is a flammable solid; burns with an intense flame. Sulfur dust in the container can be a moderate fire risk; may be a skin irritant. Charcoal is a flammable solid. Silicon is flammable in powder form. Wear chemical splash goggles and chemical-resistant gloves when examining element samples. Remind students to wash their hands thoroughly with soap and water before leaving the laboratory. Follow all laboratory safety guidelines. Please review current Safety Data Sheets for additional safety, handling and disposal information.

Disposal

The Flinn Hands-On Chemical Element Set is meant to be used year after year. Keep the samples in their original containers and store in the original kit box in a locked chemical storeroom or cabinet when not in use.

Procedure

The following are some suggested activities for the element set.

1. Element of the Week: Place a new element on your desk each week. Assign the students the task of researching the element and preparing a written report. Written reports should include the element's symbol, atomic number, atomic mass, density, appearance (luster), discovery and sources as well as interesting facts about the element and its uses. The CRC Handbook of Chemistry and Physics, the Merck Index and the Web Elements website (www.webelements.com/webelements/index.html) are useful references for this assignment.
2. Period/Group Relationships: When discussing a period or group of elements (such as group 14 or periods 3 and 4), show students the member elements. Discuss periodic trends in their properties (e.g., density, reactivity).
3. Metals: Explain to students that many elements are metals. This large group of elements tends to be lustrous in appearance, malleable in nature and, in general, are good conductors of heat and electricity. Metals tend to be reactive, as they readily lose electrons—this oxidation can often be observed as tarnish on the surface of metals. Metals included in this set are magnesium, iron, nickel, copper, zinc, aluminum, tin and lead. Allow students to observe differences in the appearance and malleability of the metals.
4. Nonmetals: Most of the elements that fall into this category are found in the upper right hand corner of the periodic table. Nonmetals gain electrons in reactions, and have a tendency to form covalent bonds with other nonmetals. Carbon and sulfur represent the nonmetals in this set. Have students compare and contrast the characteristics of metals.
5. Metalloids: Elements considered metalloids fall along the line which divides the metals from the nonmetals on the periodic table. Metalloids display properties representative of both metallic and nonmetallic elements. Metalloids are considered semiconductors (i.e., they possess less conducting ability than true metals, but are better conductors than the nonmetals. Silicon is a metalloid included in this set.
6. Making Compounds: Students often have difficulty understanding how the properties of compounds can be so different than the elements from which they are made. A useful demonstration or project for students is to choose a compound and place a small sample in a vial or a test tube. Samples of the elements that make up the compound should be placed in separate vials. For example: Copper sulfate would be exhibited next to samples of copper and sulfur. To make this activity economical, segregate the elements and compounds that are available. The vials can be emptied back into these bottles at a later time and the chemicals can be reused for this project each year. Be careful to prevent accidental mixing of chemicals.
7. Allotropic Forms of Carbon: Have students compare the feel of graphite and charcoal. Discuss polymorphism and allotropy with students using carbon as an example. Explain that diamonds are a third allotropic form of carbon. Cover the differences in the crystalline structure between the various forms of the element.
8. Creative Additions: Add to your element set in a creative way. For example: An “empty” beaker demonstrates the presence nitrogen or oxygen. Fill a balloon with helium. Silver and gold are found in jewelry and (some) coins. Discarded neon advertising signs contain the inert gas. Encourage students to read labels and locate samples of elements.

Teacher Tips

• If you are rigorous about showing the elements as you talk about them, your students’ expectation levels will change. They will expect to see chemicals, especially the exotic-sounding ones, such as iron(III) nitrate nonahydrate. They will start asking questions: “Will gallium really melt in your hand?” “Can you see a difference between ferric chloride and ferrous chloride?” Be prepared! Start building your collection of elements and compounds now.