Announcing Chemical Interactions

A typical day presents us with countless opportunities to wonder. I wonder what this bagel is made of. What happens to water when it freezes? Where does sugar go when I put it in iced tea? Why do bubbles form when I mix vinegar and baking soda? How does cocoa get hot on the stove, and how does orange jj­uice get cold in the refrigerator? These are all interesting questions.

You and your students will pursue answers to these questions in the Chemical Interactions Course for Announcing Chemical Interactions FULL OPTION SCIENCE SYSTEM grades 7–8. Students design and conduct investigations, gather, organize, and analyze data, and develop models and explanations to express their understanding of mundane, but provocative, everyday events and experiences. Multimedia animations and simulations enhance students’ concept development, and their ideas are reinforced and extended through readings developed specifically for this course.

The Chemical Interactions Course provides students with their first engagement with a number of fundamental, highly abstract concepts, which are essential for grappling with the two big questions in chemistry: What is common matter composed of? In what ways does matter change and under what conditions?

As the course unfolds, students develop these understandings.

• Matter is made of particles called atoms.

• Ninety different kinds of atoms, each representing an element, occur naturally on Earth.

• A substance is a unique form of matter.

• The basic particles of the millions of substances on Earth are combinations of the 90 naturally occurring kinds of atoms.

• The particles in substances are in constant motion.

• Particles in motion have kinetic energy.

• There is only space between particles.

• The kinetic energy of particles is related to heat.

• The greater the kinetic energy, the greater the heat.

• Energy transfers from one particle to another when they collide.

• Energy transfer by contact is conduction.

• When particles acquire energy, they move faster and hit other particles harder. This pushes particles farther apart, causing expansion.

• Energy transfer (to and from particles in a substance) causes phase change.

• A solution occurs when one substance breaks down into individual particles (dissolves) and becomes distributed uniformly among the particles of another substance.

• During a chemical reaction, starting substances transform into new substances when the atoms in particles of the starting substances rearrange to form new particles.

• During a chemical reaction, starting substances transform into new substances when the atoms in particles of the starting substances rearrange to form new particles.

The Chemical Interactions Course is not a simplified high school chemistry course. Students are not introduced to atomic structure—proton, neutron,electron orbitals—and the electrical properties of atoms that predict their reactivity. Bonds are mentioned only in passing as the attractive forces that hold atoms together in particles. The content of the Chemical Interactions Course stays focused on four big ideas: particulate theory of matter; combination and recombination of atoms to form substances; kinetic theory of particle interaction; and the effects of energy transfer. These ideas are prerequisite to the more advanced, increasingly mathematical concepts that students will encounter in a few years. We believe the content of this course provides the conceptual foundation on which students can build the more rigorous, intellectually demanding concepts they will encounter in high school.

The design of the Chemical Interactions Course also agrees with guidelines set forth in the soon-to-be-released major report from the National Research Council, Taking Science to School—Learning and Teaching Science in Grades K–8. The report describes a recommended learning progression for chemistry education, identifying the following concepts as appropriate for students in the seventh and eighth grades.

• Matter is composed of discrete particles (atoms).

• There is empty space (vacuum) between particles.m Each atom takes up space, has mass, and is in constant motion.

• Over 100 different kinds of atoms exist; each kind has distinctive properties, including its mass and the way it combines with other atoms or molecules.

• Atoms can be joined (in different proportions) to form molecules
and networks—a process that involves forming chemical bonds between atoms.

• Molecules have different characteristic properties than the atoms from which they are composed.

So, what is the most common element in our Solar System, and which element is most common on Earth? In the atmosphere? In you? What is temperature? Why does steel expand when it gets hot? How can water evaporate from a pan that is well below the boiling temperature? Why does a cup of hot cocoa cool down? What causes butter to melt? If you are not sure, ask your middle school students after they have traveled the FOSS Chemical Interactionss­ path. They’ll know the answers.