Alaska Science
Key Element A2

A student who meets the content standard should understand the physical, chemical, and nuclear changes and interactions that result in observable changes in the properties of matter (Changes and Interactions of Matter).

Performance Standard Level 4, Ages 15–18

Students describe and explain a common chemical reaction including atomic structure, chemical bonding and reaction rates.

Sample Assessment Ideas

• Students burn (or attempt to burn) four different substances; make qualitative and quantitative evaluations before and after combustion; state what has happened in each combustion attempt.

• Students use metals and non-metals in a reaction with hydrochloric acid; make qualitative and quantitative evaluations before and after the reactions; use chemical symbols and models to describe each chemical reaction.

Expanded Sample Assessment Idea

• Students build a bottle “firework” using hydrochloric acid and calcium carbonate; explain the complete reaction; relate the chemical reaction to the production of cave formations. [Proper SAFETY should be used.]

Materials

• 1 or 2 liter plastic bottle
• rubber stopper to fit
• streamers to tape to stopper
• calcium carbonate
• hydrochloric acid OR vinegar (vinegar can be used but it gives the students a more difficult equation)
• balance
• graduated cylinder
• paper towels

Procedure

Students will:

1. Measure a given mass (about 1 gram) of calcium carbonate; place in a paper twist.

2. Measure 5–10 mL of 0.1M hydrochloric acid into a bottle.

3. Place the paper twist of carbonate in the bottle and rapidly cork the bottle.

4. Shake to mix the chemicals; DO NOT POINT at anyone.

5. Make complete lab records in a journal about what was observed and what happens.

6. Write equations to explain what is observed.

Reflection and Revision

How does this activity relate to the formation of stalactites and stalagmites in caves? To the weathering of marble statues in industrial cities? Instead of popping the cork, design a way to test the gas that is produced and prove its identity; get approval of the design; carry out the tests; interpret the results in a journal.

Levels of Performance

Standards Cross-References
( Alaska Department of Education & Early Development Standards)

National Science Education Standards

The nuclear forces that hold the nucleus of an atom together, at nuclear distances, are usually stronger than the electric forces that would make it fly apart. Nuclear reactions convert a fraction of the mass of interacting particles into energy, and they can release much greater amounts of energy than atomic interactions. Fission is the splitting of a large nucleus into smaller pieces. Fusion is the joining of two nuclei at extremely high temperature and pressure, and is the process responsible for the energy of the sun and other stars. (Page 178)

Radioactive isotopes are unstable and undergo spontaneous nuclear reactions, emitting particles and/or wavelike radiation. The decay of any one nucleus cannot be predicted, but a large group of identical nuclei decay at a predictable rate. This predictability can be used to estimate the age of materials that contain radioactive isotopes. (Page 178)

Atoms interact with one another by transferring or sharing electrons that are furthest from the nucleus. These outer electrons govern the chemical properties of the element. (Page 178)

Bonds between atoms are created when electrons are paired up by being transferred or shared. A substance composed of a single kind of atom is called an element. The atoms may be bonded together into molecules or crystalline solids. A compound is formed when two or more kinds of atoms bind together chemically. (Page 179)

The physical properties of compounds reflect the nature of the interactions among its molecules. These interactions are determined by the structure of the molecule, including the constituent atoms and the distances and angles between them. (Page 179)

Carbon atoms can bond to one another in chains, rings, and branching networks to form a variety of structures, including synthetic polymers, oils, and the large molecules essential to life. (Page 179)

Chemical reactions occur all around us, for example in health care, cooking, cosmetics, and automobiles. Complex chemical reactions involving carbon-based molecules take place constantly in every cell in our bodies. (Page 179)

Chemical reactions may release or consume energy. Some reactions such as the burning fossil fuels release large amounts of energy by losing heat and by emitting light. Light can initiate many chemical reactions such as photosynthesis and the evolution of urban smog. (Page 179)

A large number of important reactions involve the transfer of either electrons (oxidation/reduction reactions) or hydrogen ions (acid/base reactions) between reacting ions, molecules, or atoms. In other reactions, chemical bonds are broken by heat or light to form very reactive radicals with electrons ready to form new bonds. Radical reactions control many processes such as the presence of ozone and greenhouse gases in the atmosphere, burning and processing of fossil fuels, the formation of polymers, and explosions. (Page 179)

Chemical reactions can take place in time periods ranging from the few femtoseconds (10 –15 seconds) required for an atom to move a fraction of a chemical bond distance to geologic time scales of billions of years. Reaction rates depend on how often the reacting atoms and molecules encounter one another, on the temperature, and on the properties—including shape—of the reacting species. (Page 179)

Catalysts, such as metal surfaces, accelerate chemical reactions. Chemical reactions in living systems are catalyzed by protein molecules called enzymes. (Page 179)

Benchmarks

The nucleus of radioactive isotopes is unstable and spontaneously decays, emitting particles and/or wavelike radiation. It cannot be predicted exactly when, if ever, an unstable nucleus will decay, but a large group of identical nuclei decay at a predictable rate. This predictability of decay rate allows radioactivity to be used for estimating the age of materials that contain radioactive substances. (Page 80)

Atoms often join with one another in various combinations in distinct molecules or in repeating three-dimensional crystal patterns. An enormous variety of biological, chemical, and physical phenomena can be explained by changes in the arrangement and motion of atoms and molecules. (Page 80)

The configuration of atoms in a molecule determines the molecule’s properties. Shapes are particularly important in how large molecules interact with others. (Page 80)

The rate of reactions among atoms and molecules depends on how often they encounter one another, which is affected by the concentration, pressure, and temperature of the reacting materials. Some atoms and molecules are highly effective in encouraging the interaction of others. (Page 80)