We are now going to delve into the heart of chemistry. We learn ways of representing molecules and how molecules react. To do this, we'll even think about "how many" of a molecule we have using a quantity called a "mole".
Polymers are a vital part of our everyday lives and nearly all consumer products have a plastic component of some variation. Students explore the basic characteristics of polymers through the introduction of two polymer categories: thermoplastics and thermosets. During teacher demos, students observe the unique behaviors of thermoplastics. The fundamentals of thermoset polymers are discussed, preparing them to conduct the associated activity in which they create their own thermoset materials and mechanically test them. At the conclusion of this lesson-activity pair, students understand the basics of thermoplastics and thermosets, which may entice their interest in polymer engineering.
Students investigate the property dependence between concentrations and boiling point. In section 1, students first investigate the boiling point of various liquid solutions. In section 2, they analyze data collected by the entire class to generate two boiling point curves, one for salt solutions and one for sugar solutions. Finally, in section 3, students use the data they have analyzed to determine how to create a solution that has a particular boiling point and is a cost-effective design.
A concentration gradient occurs when the concentration of particles is higher in one area than another. In passive transport, particles will diffuse down a concentration gradient, from areas of higher concentration to areas of lower concentration, until they are evenly spaced.
This 11-minute video lesson looks at Potassium-Argon (K-Ar) dating and it can be used to date very old volcanic rock and the things that might be buried in between. [Cosmology and Astronomy playlist: Lesson 79 of 85]
Students create silver nanoparticles using a chemical process; however, since these particles are not observable to the naked eye, they use empirical evidence and reasoning to discover them. Students first look for evidence of a chemical reaction by mixing various solutions and observing any reactions that may occur. Students discover that copper and tannic acids from tea reduce silver nitrate, which in turn form silver. They complete the reaction, allow the water to evaporate, and observe the silver nanoparticles they created in plastic dishes using a stereo microscope. Students iterate on their initial process and test to see if they can improve the manufacturing process of silver nanoparticles.
Concluding a two-part lab activity, students use triple balance beams and graduated cylinders to take measurements and calculate densities of several household liquids and compare them to the densities of irregularly shaped objects (as determined in Part 1). Then they create density columns with the three liquids and four solid items to test their calculations and predictions of the different densities. Once their density columns are complete, students determine the effect of adding detergent to the columns. After this activity, present the associated Density & Miscibility lesson for a discussion about why the column layers do not mix.
After students conduct the two associated activities, Density Column Lab - Parts 1 and 2, present this lesson to provide them with an understanding of why the density column's oil, water and syrup layers do not mix and how the concepts of density and miscibility relate to water chemistry and remediation. Topics covered include miscibility, immiscibility, hydrogen bonds, hydrophobic and hydrophilic. Through the density column lab activities, students see liquids and solids of different densities interact without an understanding of why the resulting layers do not mix. This lesson gives students insight on some of the most fundamental chemical properties of water and how it interacts with different molecules.
Learn about how particles move from an area of greater concentration to an area of lesser concentration through the process of diffusion.
Students demonstrate the erythrocyte sedimentation rate test (ESR test) using a blood model composed of tomato juice, petroleum jelly and olive oil. They simulate different disease conditions, including rheumatoid arthritis, anemia, leukocytosis and sickle-cell anemia, by making appropriate variations in the particle as well as in the fluid matrix. Students measure the ESR for each sample blood model, correlate the ESR values with disease conditions and confirm that diseases alter blood composition and properties. During the activity, students learn that when non-coagulated blood is let to stand in a tube, the red blood cells separate and fall to the bottom of the tube, resulting in a sediment and a clear liquid called serum. The height in millimeters of the clear liquid on top of the sediment in a time period of one hour is taken as the sedimentation rate. If a disease is present, this ESR value deviates from the normal, disease-free value. Different diseases cause different ESR values because blood composition and properties, such as density and viscosity, are altered differently by different diseases. Thus, the ESR test serves as a real-world diagnostic screening test to identify indications of the presence of any diseases in people.
Students experiment with various ways to naturally dye materials using sources found in nature—roots, leaves, seeds, spices, etc.—as well as the method of extracting dyes. Then they analyze various materials using statistical methods and tackle an engineering design challenge—to find dyes that best suit the needs of a startup sustainable clothing company.
To gain an understanding of mixtures and the concept of separation of mixtures, students use strong magnets to find the element of iron in iron-fortified breakfast cereal flakes. Through this activity, they see how the iron component of this heterogeneous mixture (cereal) retains its properties and can thus be separated by physical means.
So we know that all matter is made up of atoms, but what is an atom made out of? Chemists describe the structure of atoms using models. This section will cover the Bohr model, photoelectric effect, absorption and emission spectra, quantum numbers, and electron configurations.
In this electrochemistry activity, learners will explore two examples of electroplating. In Part 1, zinc from a galvanized nail (an iron nail which has been coated with zinc by dipping it in molten zinc) will be plated onto a copper penny. In Part 2, copper from a penny will be plated onto a nickel.
This activity from the Exploratorium provides instructions to build an electroscope, a device that detects electrical charge. Common, inexpensive materials including film canisters, 3-M Scotch Magic™ Tape, and a plastic comb are used to show the attractions and repulsions between positively and negatively charged objects. The site also provides an explanation of the results and suggestions for extension activities.
Students gain a better understanding of the different types of materials as pure substances and mixtures and learn to distinguish between homogeneous and heterogeneous mixtures by discussing an assortment of example materials they use and encounter in their daily lives.
How elements relate to atoms. The basics of how protons, electrons, and neutrons make up an atom. Created by Sal Khan.
Under the "The Science Behind Harry Potter" theme, a succession of diverse complex scientific topics are presented to students through direct immersive interaction. Student interest is piqued by the incorporation of popular culture into the classroom via a series of interactive, hands-on Harry Potter/movie-themed lessons and activities. They learn about the basics of acid/base chemistry (invisible ink), genetics and trait prediction (parseltongue trait in families), and force and projectile motion (motion of the thrown remembrall). In each lesson and activity, students are also made aware of the engineering connections to these fields of scientific study.
Students are introduced to polymer science and take on the role of chemical engineers to create and test a plastic made from starch. After testing their potato-based plastic, students design a product that takes advantage of the polymer’s unique properties. At the end of the engineering design process, students present their product in a development “pitch” that communicates their idea to potential investors.
Enzymes as catalysts for reactions in biological systems; discussion of substrates, active sites, induced fit, and activation energy.