Atoms, ions, and molecules are the individual particles that make up matter. They are very small — too small to work with on an individual level (although scientists are getting very close as nanotechnology advances). We will look at the mole, a grouping of particles that makes it easier to relate a measurable quantity of elements or compounds (in milligrams, grams, or kilograms) to the number of atoms or molecules. Next we will look at three types of chemical change (chemical reactions) and show how to symbolize chemical change. Finally, we will use the concept of moles and mass and the material just learned about chemical reactions to relate the mass of starting materials (reactants) in a chemical reaction to the mass of materials after the reaction takes place (the products).
