Hands-on Activity Element, Mixture, Compound

Learning Objectives

After this activity, students should be able to:

• Distinguish and describe the three types of matter: elements, compounds, mixtures.
• Define pure and impure materials.
• Give some examples of elements, mixtures, and compounds.
• Explain the different properties of each group of materials.
• Explain how chemical engineers use these terms when solving problems related to water purification and distillation of crude oil.
• Explain how material and mechanical engineers use these terms regarding creating new composite materials.
• Explain what metal alloys are and explain the significance of metal alloys in material science and material engineering.
• Give some applications of non-metal alloys.

Educational Standards

Each TeachEngineering lesson or activity is correlated to one or more K-12 science, technology, engineering or math (STEM) educational standards.

All 100,000+ K-12 STEM standards covered in TeachEngineering are collected, maintained and packaged by the Achievement Standards Network (ASN), a project of D2L (www.achievementstandards.org).

In the ASN, standards are hierarchically structured: first by source; e.g., by state; within source by type; e.g., science or mathematics; within type by subtype, then by grade, etc.

International Technology and Engineering Educators Association - Technology

State Standards

Materials List

To share with the entire class:

• 20 sets of bolts, nuts and washers
• 9 plastic dishes
• tape and marker, to number dishes
• four examples of elements:
• aluminum (one small sheet of foil)
• copper (a small piece of wire or tubing)
• iron (filings or a magnet)
• carbon (in the form of a pure carbon pencil or graphite)
• four examples of compounds:
• water, or H₂0 (~100 mL)
• table salt, or NaCl (~10g)
• baking soda, or NaHCO₃ (~10g)
• eggshell or a seashell, or CaCO₃
• four examples of mixture, both homogeonous and heteogenous:
• inflated Ziploc bag (as an example of air)
• bottle of Coke or other soda
• salad dressing (such as a vinegarette made of oil and water)
• salt water
• Data Table, one per student

Worksheets and Attachments

Introduction/Motivation

We are all completely surrounded by matter. To better understand this matter—how it affects you, how you affect it and how it can be manipulated to our benefit—we need get a basic understanding of the types and properties of matter. The diversity of the matter in the world and in the universe is astounding. If we are to understand this diversity, we must start with a way of organizing and describing matter.

All matter is made of elements that are fundamental substances that cannot be broken down by chemical means. An element is a substance that can not be further reduced as to simpler substances by ordinary processes. In essence, an element is a substance consisting of one type of atom. 

A compound is a pure substance composed of two or more different atoms chemically bonded to one another. That means that it can not be separated into its constituents by mechanical or physical means and only can be destroyed by chemical means.

A mixture is a material containing two or more elements or compounds that are in close contact and are mixed in any proportion. For example, air, sea water, crude oil, etc. The constituents of a mixture can be separated by physical means like filtration, evaporation, sublimation and magnetic separation. The constituents of a mixture retain their original set of properties. Further, mixtures can be classified to homogeneous and heterogeneous mixtures. A homogeneous mixture has the same uniform appearance and composition throughout its mass. For example, sugar or salt dissolved in water, alcohol in water, etc. A heterogeneous mixture consists of visibly different substances or phases. The three phases or states of matter are gas, liquid and solid. A heterogeneous mixture does not have a uniform composition throughout its mass.

New materials are among the greatest achievements of every age and they have been central to the growth, prosperity, security and quality of life of humans since the beginning of history. New materials open the door to new technologies, whether in civil, chemical, construction, nuclear, aeronautical, agricultural, mechanical, biomedical or electrical engineering.

The study of metal alloys, which are mixture of different metals, is a significant part of materials science and material engineering. Of all the metallic alloys in use today, the alloys of iron (steel, stainless steel, cast iron, tool steel, alloy steels) make up the largest proportion both by quantity and commercial value. Iron alloyed with various proportions of carbon gives low, mid and high carbon steels. For the steels, the hardness and tensile strength of the steel is directly related to the amount of carbon present, with increasing carbon levels also leading to lower ductility and toughness. The addition of silicon and graphitization produce cast iron. The addition of chromium, nickel and molybdenum to carbon steels (more than 10%) gives us stainless steels.

Other significant metallic alloys are those of aluminium, titanium, copper and magnesium. Copper alloys have been known for a long time (since the Bronze Age), while the alloys of the other three metals have been relatively recently developed. The alloys of aluminium, titanium and magnesium are also known and valued for their high strength-to-weight ratios and, in the case of magnesium, their ability to provide electromagnetic shielding. These materials are ideal for situations in which high strength-to-weight ratios are more important than bulk cost, such as in the aerospace industry and certain automotive engineering applications.

Other than metals, polymers and ceramics are also an important part of materials science. Polymers are the raw materials (the resins) used to make what we commonly call plastics. Plastics are really the final product, created after one or more polymers or additives have been added to a resin during processing, which is then shaped into a final form.

Another industry application is the making of composite materials. Composite materials are structured materials composed of two or more macroscopic phases. Applications range from structural elements such as steel-reinforced concrete, to the thermally insulative tiles that play a key and integral role in NASA's Space Shuttle thermal protection system, which protects the surface of the shuttle from the heat of re-entry into the Earth's atmosphere. One example is reinforced carbon-carbon (RCC), The light gray material withstands reentry temperatures up to 1510 °C (2750 °F) and protects the Space Shuttle's wing leading edges and nose cap. RCC is a laminated composite material made from graphite rayon cloth and impregnated with a phenolic resin.

Other examples can be seen in the "plastic" casings of television sets, cell phones and other modern devices. These plastic casings are usually a composite material.

Procedure

Before the Activity

Gather materials and make copies of the Data Table, one per student.

Prepare nine plastic dishes of bolts, nuts and washers as described below. Place them on a table (called Table A). Indicate the dish numbers in some way, such as with tape and a marker.

• Dish 1: 4 washers
• Dish 2: 4 bolts
• Dish 3: 4 nuts
• Dish 4: combine 1 nut with 1 bolt (4 sets)
• Dish 5: combine 2 nuts with 1 bolt (4 sets)
• Dish 6: combine 1 nut and 1 washer with 1 bolt (4 sets)
• Dish 7: 1 washer, 1 nut, 1 compound as in dish 5 and 1 compound as in dish 6
• Dish 8: 2 washers, 1 nut, and 2 bolts
• Dish 9: 1 compound as in dish 4 and 2 compound as in dish 5.

Place the examples of elements, compounds, and mixtures on another table (called Table B) and label them. You may also label the compounds with their specific chemical formula (for example, table salt would be NaCl). 

With the Students

1. Divide the class into groups of four students each. Hand out the blank data tables.
2. Direct each student's attention to Table A. The sets of washers, bolts and nuts can be used to convey the concept of elements, mixtures and compounds. Explain to the students that if they think each washer, bolt and nut as an individual atom then the contents of dishes 1, 2 and 3 are elements because they are all the same atom and that can not be further reduced as to simpler substances. The contents of dishes 4, 5 and 6 are compound because they show one substance composed of two or more different atoms chemically bonded to one another and the contents of dishes 7, 8 and 9 are mixtures because they are materials containing two or more elements or compounds and are mixed in any proportion.
3. After the discussion about Table A, direct each group to go through Table B and compare and contrast the different items on the table and make a list of their discussion. Have them categorize the materials in each dish as element, homogenous mixture, heterogeneous mixture or compound, recording this in their data tables. Ask students to discuss their lists. (Expect some to categorize the materials as elements, mixtures and compounds.)
4. At this point, explain the different types of matter, using the classroom board as needed. Then, discuss all the materials on Table B again and separate them to classes of elements, mixtures (homogeneous and heterogeneous) and compounds.

Vocabulary/Definitions

compound: A pure chemical substance consisting of two or more different chemical elements.

element: A substance consisting one type of atom.

heterogeneous mixture: A mixture that consists of visibly different substances or phases.

homogeneous mixture: A mixture that has the same uniform appearance and composition throughout its mass.

mixture: A substance consisting of two or more materials that aren't chemically combined.

solution: A homogeneous mixture composed of two or more substances.

Assessment

Questions: Ask students the Investigating Questions as part of a concluding class discussion. Students' answers and contributions to the discussion reveal their comprehension of the activity concepts. Alternatively, ask students to individually answer the questions in the form of a final written test.

Investigating Questions

• Describe the three types of matter: elements, compounds and mixtures.
• Define pure and impure materials.
• Give some examples of elements, mixtures, and compounds.
• Explain the different properties of each group of materials.
• Explain how chemical engineers use these terms when solving problems related to water purification and distillation of crude oil.
• Explain how material and mechanical engineers use these terms regarding creating new composite materials.
• Explain what metal alloys are and explain the significance of metal alloys in material science and material engineering.
• Give some applications of nonmetal alloys.

Copyright

Contributors

Supporting Program

Acknowledgements

This digital library content was developed by the University of Houston's College of Engineering under National Science Foundation GK-12 grant number DGE 0840889. However, these contents do not necessarily represent the policies of the NSF and you should not assume endorsement by the federal government.