Science ObjectDigital resources are stored online in your NSTA Library.
Science Objects are two hour on-line interactive inquiry-based content modules that help teachers better understand the science content they teach. This Science Object is the third of four Science Objects in the Chemical Reactions SciPack. It demonstrates how chemical reactions can take place in time periods ranging from the few femto-seconds (10-15 seconds) required for an atom to move a fraction of a chemical bond distance to geologic time scales of billions of years. The rate of reactions among atoms and molecules depends on how often they encounter one another, which is affected by the concentration, pressure (for gases), and temperature of the reacting substances. The configuration of atoms in a molecule determines the molecule's properties. Shapes are particularly important in determining how large molecules interact with others. Some atoms and molecules called catalysts are highly effective in accelerating chemical reactions. Chemical reactions in living systems are catalyzed by protein molecules called enzymes.